US2732817A

US2732817A - Bobbin having a controlled unwinding

Info

Publication number: US2732817A
Authority: US
Publication date: 1956-01-31
Anticipated expiration: 1973-01-31

Description

Jan. 31, 1956 R. N. ROBINSON 2,732,317

BOBBIN HAVING A CONTROLLED UNWINDING Filed Oct. 28, 1953 INVENTOR. 1 Rowland N.Ro|:a1nson ATTORNE Y United States Patent C) BOBBIN HAVING A CONTROLLED UNWINDING Rowland N. Robinson, Worcester, Mass., assignor to The Robinson Thread Company, Worcester, Mass a corporation of Massachusetts Application October 28, 1953, Serial No. 388,807

Claims. (Cl. 112-251) This invention relates to a bobbin of wound layers of thread made of artificial fibres, and more particularly to a bobbin filled with such thread which is primarily adapted for use in a high speed sewing machine.

The standard natural fibre thread, such as cotton, has crinkled fibres projecting laterally which so interlock that juxtaposed thread convolutions wound on a bobbin cling together somewhat and thus present a slight degree of friction or resistance to unwinding which tends to hold the thread in place and insure an orderly feeding of the thread from the bobbin in a sewing machine shuttle. On the other hand, modern types of thread made of artificial or synthetic polymeric fibers, such as anylonpolyamide .substance, are cylindrical filaments which offer but little adhesion at the surface to adjacent :thread portions. Consequently, when a bobbin filled with such artificial thread is employed in a high speed sewing machine shuttle and the machine is stopped abruptly, as is customary in industrial usage, the bobbin continues to spin and the comparatively slippery or non-cohering convolutions of the thread tend to unwind from the bobbin and be ,caughtaround the bobbin post or otherwise entangled in the shuttle. Such spilling, unwinding or ibacklashing of the thread results in breakage of the thread and interferes with the sewing operation.

It has been proposed toomit the core and end disks of an external delivery bobbin .and .to form a self-supporting cotton thread mass by impregnating the wound thread with wax. This has proven impractical, especially because the shape ultimately becomes distorted so that the bobbin will not fit over a-shuttle post properly. Also, the force required to turn the bobbin increases as the radius of the wound thread body decreases, especially toward the end of the thread supply, and "this variation in the thread tension interferes with the setting of the stitch and proper concatenation of the "loops in the seam, so that the machine operator :commonly removes and throws away the bobbin while it still contains considerable thread. It hasalso been proposed tomake the bobbin end disks of paper and to glue them directly'to the mass of wound cotton thread, but this has required the use of a strongly bonding adhesive which interferes with the thread unwinding'as rwellas leaves an abrasive powdery deposit in the shuttle. Attempts have been made similarly to use sheet gelatin for the :bobb'in ends, or to dip the ends of the thread :body i'nmolten wax and die press the coating into .the acquired bobbin end shape. Such gelatin or wax ends are supported solely by the thread, so that as the thread unwinds the support decreasesin diameter and area until one or both of the end disks becomes separated from the core and the thread then .catches around the shuttle post and breaks. Such wax ends were also to be die imprinted with lines of weakness, so that the 'wax which clings strongly to the cotton fibres could break away in fragments and the ends would .disappearas the thread unwound, but this required that the thread carry adhering pieces of wax which could interfere with the sewing operation. In order to heat insulate a central delivery bobbin of waxed thread used for sewing leather and thus to prevent collapse of the thread mass, it has been proposed to coat the outer surfaces of the bobbin with sodium silicate or to cement disks of fibrous material on the bobbin ends. Such procedures are not applicable to an external or peripheral delivery bobbin of artificial fibre thread. 7

In my experimentation, I have found that an artificial or man-made fibre thread, such as nylon, should be held in position on the bobbin core under a controlled restraint so that it may unwind substantially freely and yet cannot unwind or spill materially, such as when the bobbin is dropped onto the floor or overspins in the shuttle.

The primary object of my invention is to provide an external delivery bobbin of layer wound artificial or synthetic polymeric fibre "thread which will unwind under a controlled restraint but substantially freely in the shuttle and not interfere with the sewing machine operation, whereby the thread is held in place and delivered under a suitable but light tension which insures a uniform setting of the stitch formation and resists the tendency for the shuttle to continue to spin when the machine is stopped,

H so that the thread cannot unwind accidentally into a loose and tangled mass but is held substantially in place on the bobbin core by an adhesive force which may also serve for rewinding on the spinning bobbin any thread that has become loose in the machine. Further objects will be apparent in .the following disclosure.

in accordance with this invention, I employ a synthetic or artificial fibre thread, asherei-n defined, and I wind this thread on a bobbin core in a helical'winding and preferably in a criss-crosslayered arrangement so that the thread will travel rapidly from one side to the other as the thread is unwound. .A standard filled "bobbin weighs 3 to 4 grams. The thread convol-utions thereof are tacked to adjacent or contiguous thread portions or convolutions to provide a'slight resistance to an accidental unwinding by means of an adhesive cement capable of adhering to the synthetic fibre substance and of being entrapped in the thread intermeshes and =aifixing the thread convolutions with a slightdegree-of adhesion which holds the thread in place during disusej but :without providing a sticky, gummy or powdery mass as the thread is unwound. Although there is wide latitude as to the area of adhesion, it is preferably established at spaced intervals and for only .a slight linear distance along the thread. For a cross wound thread, the adhesions are preferably at the ends of the thread mass and are usually spaced linearly of the thread by a :distance of not more than about the circumference of the'th'read wound layer, such "as one or two points iforeach layer, as shown in Fig. 1, although the spacing may be widely varied for the diiferent types of :thread. The thread winding may have adhesive arranged between spaced convolu'tions in a line or band, as shown in Fig. 5, or I *may'employ a plurality of such radial .adhesions spaced parallel with the bobbin axis or a continuous band of slightly adhering cement throughout the entire bo'b'bin length. These adhesions provide a slight resistance to the unwinding pull and yet permit a substantially free unwinding under the normal thread tension of a-sew'ing operation. The force required to free the thread end {from the bobbin s'holild be sufiicient to insure that the thread is tacked to the thread body and preferably with enough but not greater strength than is needed barely carry the weight of the bobbin when suspended from that threadend The adhesive substance is selected from "a group of substances capable of adhering-to .the synthetic fibre, and it 'is preferably a plasticized thermoplastic polymerized resin body or a solution'thereof, which causes adhesion of adjacent thread layers or convolutions and yet becomes such a part of the thread substance that when the thread adhesion is pulled apart there is no scattering of adhesive or powdery material which can in any way interfere with the sewing operation.

Referring to the drawings:

Fig. 1 is a digrammatic view, partly broken away, of a bobbin carrying a cross-wound thread having a cement applied to the sides of the thread body;

Fig. 2 is a diagrammatic view of a few juxtaposed cross-wound thread portions showing their relation to the adherent side coating of cement;

Fig. 3 is a fragmentary end view of a few convolutions of thread on the bobbin; v

Fig. 4 is a diagrammatic fragmentary view of mechanism for applying the adhesive to the sides of the thread mass; and

Fig 5 is a diagrammatic view of a thread mass wound on a bobbin and having a narrow line of cement applied to its convolutions, and showing an applicator for the cement. Y

The spaced adhesions are preferably provided by applying a suitable adhesive to a side and preferably both sides of the cross-wound bobbin thread mass, which insures an adhesion of contiguous loops of the crosswound thread at the edge of the bobbin where the thread changes its direction of travel, as is indicated in Figs. 2 and 3. It is also feasible to apply the adhesive progressively to the periphery of the thread mass during the winding step, as shown in Fig. 5, such as by means of an adhesive feeding disk rolling against the periphery of the winding thread which deposits a narrow band of adhesive on the top of the mostrecently wound thread layer, so that as the next layer is laid thereover the two will'stick together at this narrow band. Several bands of adhesive or a single wide band of any desired width may be used on the various types of thread winding.

Referring first to Figs. 1 to 3 inclusive, a bobbin usually comprises a hollow cylindrical core 10, which may be made of paper, plastic, metal or other suitable material, and disc-shaped ends 11 of the same or other material suitably secured to the core, as by flaring the outer projecting ends of the core laterally (Fig. 1) to form flanges lapping over the outer faces of the disks. The thread is wound on the core before the disks 11 are applied, in accordance with standard practice, to provide a crisscross winding of the thread 12, wherein the thread is fed to the rotating bobbin by means of a reciprocating arm. If this winding is what is commonly termed a one-wind, the thread travels from one side face to the other during a single revolution of the bobbin. If the thread travels from one side of the bobbin to the other in half a bobbin revolution, this isa half-wind. A-twothirds wind is shown in Fig.1. I prefer that the winding thread make at least one transverse passage. during about one revolution of the bobbin. That thread 12 will come up to the lateral face of the bobbin, and then change its angular direction of travel at the loop or bend 13. In the next revolution of the bobbin, the thread will overlie the thread close to the previously formed loop 13, as indicated in Fig. 2, so that the side of the wound mass will present a series of these loops. .The rate of reciprocation relative to the rotation of the bobbin is preferably so governed that these loops or change of direction of the thread do not ,lie on top of one another but are disposed in an orderly fashion in concentric circles at the end of the wound thread, as shown in Fig. 3, or in other arrangement dependingon the winding operation.

In accordance with one phase of my invention, I afiix the adhesive14 to these loops 13 where they project at the side face of the bobbin and before the bobbin ends 11 are affixed to the core. That is, the. thread is wound on the cylindrical hollow core and then the adhesive is applied, and after the adhesive has set and depth of penetration by the adhesive.

accomplished its purpose the bobbin ends 11 are suitably fixed in place to form sides close to but unattached to the thread mass so that the thread will not slip off the ends of the wound mass and become entangled around the core.

The application of the plastic resin may be accomplished either manually or mechanically. Manual application of the adhesive may comprise spraying the ends of the bobbin or dipping the same in a shallow bath of the cement or a direct application by means of a paint brush or a pressure contact with a porous surface filled with a plastic resin or a solution thereof. If the application is done mechanically so as to provide a better control of the amount of adhesive, the wound bobbin mass may be suitably mounted on a spindle 15, as shown in Fig. 4, and two reciprocable carriers 16 are brought up against the side faces of the wound bobbin to apply the fluid adhesive thereto. Each carrier suitably supports a porous disk 18 of felt or other porous material which is arranged to be pressed against the side faces of the thread. A set of ducts 19 running through the carrier serves to feed the fluid adhesive to the rear of the disk 18 from an outside source and thus present a film of adhesive for application to the thread. 'Various expedients may be adopted to provide a satisfactory distribution of the adhesive. When each of these carriers 16 with its adhesive loaded disk 18 is brought into contact with the sides of the bobbin, this serves to leave a deposit of the plastic on the projecting loops 13, as shown in Figs. 1 and 2. The pressure of the plates 18 on the thread mass may be adjusted to insure an adequate Thereafter, the carriers 16 are withdrawn and the bobbin is ready for further treatment, such as for applying the disk ends 11 to the core.

It is desirable to control'the amount of adhesive applied, so as to provide a definite adhesion strength. The amount applied by the mechanism shown in Fig. 4 will depend to some extend on the pressure of the porous disks 18 against the bobbin sides as well asthe amount of plastic that is impregnated into the disks. Ordinarily, the amount is to be such that the plastic resin will not penetrate the interstices between the thread fibres or filaments for more than about three times the thickness of the thread and preferably a lesser distance. The primary requirement is that the thread will remain attached at the loop 13 to an adjacent loop or thread portion so that a free end of the thread will not ordinarily loosen from the bobbin beyond that point. It is preferable that the outside end 20 (Fig. 1) of the thread be tacked to the body at loop 13 with sufiicient adherence so that the adhesion at the loop will be just about enough to support the weight of the bobbin when suspended from the thread end. The cement is present primarily in the interstices between the threads or their multiple filaments, and there is primarily a physical interlocking of the adhesive with these filaments which holds the parts in place. Although the plastic may be of a type which dissolves the filament substance to some extent and so makes an intimate union therewith, I preferably use a non-solvent so that the bonding efiect is primarily due to its mechanical interlocking with the filaments throughout the short distance represented by the length of the loop 13, as well as by direct adhesion.

As the thread unwinds from the bobbin, the intervals between the afiixed loops 13 become shorter, since there are the same number of loops per revolution of the bobbin and these are therefore spaced more closely as the bobbin center is approached. Hence, an adhesive condition which is satisfactory for the outer convolutions of thread may provide too much adhesive at the innermost.

convolutions, and particularly since the force required to remove the thread from the bobbin increases as the bobbin diameter decreases. Hence, as a further feature of this invention, I may omit the plastic cementitious contacts or adhesions at that part of the bobbin which is nearest to the core, and preferably at least throughout the first fifth of the wound diameter of the bobbin. This is especially applicable to the large bobbins where the .periphery is at least 3 or 4 times the core circumference. This provision is not required for the smaller bobbins, where the entire side may be coated. To this end, I may provide a flange or ring 21 (Fig. 4) mounted on each carrier 16 concentrically surrounding the arbor on which the bobbin is mounted. This ring 21 acts as a guard to prevent the adhesive from touching the side of the bobbin near the core 10. The ring may be suitably mounted in a recess 22 within the carrier 16 and held forward by a helical spring 23 under compression which applies sufiicient force to hold the collar 21 against the side of the bobbin during the application of the ad hesive therearound. Hence, as indicated in Fig. 1, the adhesive may terminate at the circular line 24 and leave the innermost portion of the unwinding threadfree without any adhesive to restrain its movement. If this ring is omitted, then of course theadhesive will be applied largely throughout the entire side face of the wound mass.

According to another aspect of my invention, a line of adhesive may be applied to the periphery of the thread mass during the winding operation. This may be accomplished, as indicated in Fig. 5, by suitable mechanism comprising a metal applicator disk mounted on the shaft 31 and dipping at its lower end in a bath 32 of fluid adhesive. The shaft 31 of the disc 30 is so mounted, preferably under spring action, that the disk remains in frictional driving contact with the gradually growing periphery of the bobbin mass 34 as it is being wound. If the adhesive is not to be applied to the inner convolutions, then, as illustrated in the drawing, the wheel 39 may be brought into contact with the winding mass after the desired diameter, suchas 9% of the total diameter of the wound mass, has been attained. The disk 30 may be narrow and leave only a very slight amount of adhesive 35 on the outer-portion of each convolution or layer of the Wound thread, and the spring which holds the disk 30 against the bobbin should introduce only a controlled and slight amountof the plastic cement to the thread. threads are formed by the plastic deposited on the top of one layer of the thread mass which adheres to the next layer of thread that is applied thereover. The .net

result is the same, in that spaced adhesions are provided for desired distances or at spaced intervals. Thedisk 30 may be of suitable width, or several disks 30 may be used in parallel to provide continuous or spaced bands.

The standard'artificial fibre substances capable of use as threads comprise the standard synthetic polymeric.

resins, and particularly the linear polyamide resins, acrylic resins, polyester resins, vinyl resins, amyl resins, and copolymers thereof; and they include the cellulose base substances, such as cellulose acetate rayon, ethyl cellulose viscose rayon, cuprammonium nitrocellulose rayon,

, the protein base substances made of regenerated silk,

soy bean, zein, fish and Waste animal tissues, spun glass, and artificial fibre substances derived from natural fibres,

, such as regenerated silk or viscose made by extruding dissolved cotton linters. One example is the thermoplastic nylon condensation product of adipic acid and hexamethylene diaminc. Another such'standard thread is made of an Orion acrylonitrile. A Dacron poly-- ester thread fibre may be made from a condensate of ethylene glycol and terephthalic acid. All of these synthetic or artificial thread fibre substances are included under the general term of artificial fibre thread, and the filaments of which the threads are made are herein classed as-fibres. I

A suitable adhesive substance for tacking together spaced portions of the artificial fibre threads may be se lected from the group of polyamide, acrylic and polyester in this case, the adhesions between the d resins and the natural and synthetic rubbers suitably plasticized by plasticizers or solvents, and especially polyvinyl acetate, polyvinyl alcohol, vinyl chloride, polystyrene, nylon" polyamide type 8, polyacrylonitrile, melamine formaldehyde, the methacrylates, the cumarone resins, the furan resins and copolymers thereof, the natural and synthetic latices or solutions of rubber and the synthetic rubbers, such as the polychloroprene, polybu'ta'diene, 'polysulfide and polybutene rubbers, and various copolymers and related substances which have an affinity for and are able to adhere to and cause cohesion of adjacent synthetic or artificial thread fibres. Such substances, herein classed as poly meric resins, may be plasticized vwith various types of plasticizers or solvents which are commercially avail able, and these are employed in quantity and composition to give the desired viscosity, adhesion and other needed physical properties. It is preferred to use a plasticized resin adhesive which is not only compatible With and adheres to the artificialt'hre'ad fibre, but is insoluble in mineral oil often found objectionably present near sewing operations.

As an example of a suitable composition of general utility for the various artificial fibre threads, a polyvinyl acetate adhesive may be compounded of:

12.5 lbs. polyvinyl acetate 1.0 lb. dibutyl phthalate 0.75 lb. water i tsp. aqueous ammonia, 28% strength After application to one or both sides of the bobbin.-

wound thread, the thread may be suitably heat treated to insure hardening of the adhesive. This may be effected by curing the thread mass in an oven having air circulated at 250 F. for 15 minutes.

A nylon thread may be provided with suitable tackiness or adhesiveness by an adhesive made according to the following formula:

1 lb. nylon polyamide type 8 2 lbs. water 8 lbs. ethyl alcohol 2 oz. ethyl hexanediol This substance after application to the thread may be dried at room temperaturefor24 hrs. in order to cure the resin substance.

Another satisfactory adhesive may be formed of: 5 lbs. polyvinyl butyral (containing 50% of solids) 5 lbs. water 2 lbs. melamine It will now be appreciated that the thread tacking sub- Z stance shouldhave an alfinity for the synthetic or artificial thread fibres to the extent of adhering to and interlocking adequately-therewith, without flaking off as a brittle or abrasive powder. I have found that mucilage and many other substances which would adhere to cotton or woolen are not adequate for the purpose of tacking together the adjacent thread loops or convolutions of synthetic polymeric thread fibres, and particularly since they do not have the required tensile film strength. The. synthetic fibres do not absorb the adhesive fluid the way cotton and wool do, since the adhesion is principally due to an interlocking with the many filament strands of the synthetic thread, as well as a direct surface film adhesion. The synthetic;

polyvinyl butyral, polyfibres are hydrophilic, and I do not use a water solution of adhesive, except as water may be used as an evaporable carrier of the resin. Itis desirable that the thread con volutions be tacked together only lightly and with a substance which either disappears into the thread body or is otherwise of such' a nature as not to become separated from the thread to a detrimental extent.

The synthetic resin applied to cause cohesion of the thread convolutions is preferably applied in such a minute amount that it does not penetrate the thread body more than ordinarily three times the thickness of a single thread and the resin film should not ordinarily exceed 0.002 inch in thickness as a layer on the ends of the thread mass. The adhesion is primarilybetween very short lengths of thread where they are in contact with the neighboring thread convolution at the bobbin edge, as indicated in Fig. 2 or in a line contact, as shown in Fig. 5. For example, if the thread wound on a bobbin measures 0.005" in thickness, the resin film will ordinarily be satisfactory if itpenetrates only about 0.015" into the side of the thread mass, although this depth of penetration may vary, depending upon the nature of the thread and the usage to which it is to be put. The amount of substance em ployed is gauged to'some extent by the forces required to free the thread from the bobbin without involving a jerky motion as the thread is pulled forward. This force may be 3 to 4 grams. This involves a ratio of 0.2% to 2.0% of the tensiie strength of a nylon thread, for example. It is to be observed that threads with low tensile strengths, such as 1 lb., or with high strengths, such as 25 lbs., and with diameters varying from 0.002" to 0.025" require little difference in force to free them from the plastic coating. In each instance, the strength is merely sufficient to hold the thread mass tacked together and provide a substantially free but slightly restrained unwinding thereof and preferably to insure a back winding of any loose mass of the thread if the bobbin should spin after the machine has been stopped; The quantity of adhesive applied is controlled in part by the pressure and the duration of time of engagement of the disks 18 against the thread, as well as the quantity of fluid adhesive introduced through the ducts 19 to the disk 18. a

It is desirable to maintain the plastic mass as mobile as possible in order to obtain a uniform application to the thread on the bobbin. Ordinarily an absolute viscosity of less than 200 poises is advisable, and I prefer that this be within the range of 10 to 75 poises. The viscosity depends on the nature and quantity of plasticizer or solvent used. The penetration into the thread mass may be controlled in various ways, such as by limiting the amount applied to that which insures the proper penetration. It is desirable to limit the plasticity of the plastic resin film on the thread to a range of 10 to 50 Shore Durometer Type A hardness. In order to guard against brittleness and a consequent scraping of the material from the thread, it is preferable that the adhesive have a slight tackiness and not be brittle or in danger of sloughing off as a residual deposit in the shuttle case. The resin may be always soft, as is the case with polyethylene glycol plasticized resins.

The thread convolutions are tacked together at intervals of preferably not greater than about the circumference of a cross wound thread layer and throughout only a very short distance and particularly at spaced intervals where one adhesive coated thread convolution touches another. If the thread is a one-wind, or wherein the thread travels from one side face of the bobbin to the other during a single revolution thereof, then the tacking of one thread convolution to another will take place only at the loop where the thread changes in its direction of travel, and a typical bobbin measuring 0.75" to 1.0" in thickness will have each thread convolution aflixed to the adjacent thread mass at points of about & in length and at intervals spaced at about 2%". If the thread winding is a half windyor where the thread makes two passes across the bobbin in a single revolution of the bobbin, the

thread will make a sharper angle where it changes its direction of travel and the length of the afiixed loop portions of the thread will be slightly less than 5 and the intervals between the afiixed points will be about 1%".

If the thread is wound helically where many revolutions of the bobbin are required for the thread to travel from one end of the bobbin to the other, I may use a gang of parallel applicator disks'30 which provide spaced disklike adhesions within the thread mass, so that the linearly spaced adhesions are separated by a distance of only a small multiple of the thread layer circumference. These axially parallel adhesions prevent any accidental unwinding of a long length of thread. Where the thread is cross wound, as in Fig. 1, the adhesions are properly localized by being impregnated only into the loops 13, and the length of thread between the adhesions is determined by the nature of the cross winding, such as the length of the circumference of each thread convolution layer for a onewind. The adhesions in the winding of Fig. 5 are formed by the narrow band 35 on each thread layer which forms an internal disk of adhesions perpendicular to the axis of the thread body and located suitably anywhere between the bobbin ends, so that each thread layer is tacked to the two layers located radially of the bobbin on each side thereof.

It will be appreciated that various'rnodifications may be made in the bobbin winding and the manner of tacking the thread convolutions together and that I may employ various adhesives which are capable of adhering to the artificial fibre thread substances and forming adhesions between the convolutions which satisfy the above objects of my invention, and that the viscosity, quantity, adhesivenessand nature of the cement may be varied as needed according to the type of thread substance employed. Also,

' the extent of area or volume of impregnation may be varied widely, provided the resin cement is impregnated into v the body throughout the required portion in such a limited quantity that the thread is tacked together sufficiently to prevent an accidental unwinding but not sufiicient to bind the mass into a self-supporting unit which does not require the thread confining ends. In my bobbin, the thread is wound on a core and disk ends are required to confine the thread mass on the core so that the cement in any portion of the thread mass is present primarily to prevent accidental unwinding and not to bind the mass into a selfsupporting unit. Hence, the above disclosure of the principles of my invention and the description of preferred embodiments is not to be interpreted as imposing limitations on the appended claims.

I claim:

1. A thread bobbin comprising a core, a mass of thread formed of smooth surfaced artificial fibres cross wound thereon in helical convolutions for external delivery, the cross winding of the thread providing radially arranged loops at an end of the thread mass, an adhesive applied to the exposed loop surfaces and impregnating the loops at said end of the mass for only a short distance, the main body of the thread between the ends of the wound mass being non-coated and free for unwinding, disk ends secured on the core which are independent of and solely confine the thread mass on the core, said adhesive being a compatible heat set polymeric resin film independent of the disk ends which tacks radially adjacent thread convolutions together and provides a substantially free unwinding ofthe thread and which requires a tensile force of not over about four ounces to pull the thread free at the tacked loops.

2. A thread bobbin comprising a core, a mass of thread formed of smooth surfaced artificial fibres cross wound thereon in helical convolutions for external delivery, disk ends secured on the core which are independent of and confine the thread mass therebetween on the core, said core and disk ends formingthe sole support for the thread, and a polymeric resin adhesive independent of said disks and located in the thread interstices between adjacent convolutions which is compatible with, adheres directly to and tacks the thread in place at narrow adhesion points widely spaced linearly along the thread, the main body of the thread being non-cohesive and unwinding freely between said points, the force of adhesion at said points being only sufficient to restrain the thread against accidental unwinding without providing a resistance to unwinding during a normal use which is materially greater than that of the adjacent untacked portion.

3. A thread bobbin according to claim 2 in which the thread loops are substantially free from said adhesive for a distance outwardly from the core of at least about onefifth of the initial radial thickness of the wound thread mass.

4. A thread bobbin according to claim 2 in which the polymeric resin adhesive penetrates the thread interstices not over about three times the thickness of the thread, and the force required to break the adhesion is not substantially greater than the weight of the bobbin suspended from the free thread end.

5. A thread bobbin according to claini 2 in which the I References Cited in the file of this patent UNITED STATES PATENTS 945,562 Cone Apr. 12, 1910 1,135,470 Tolman Apr. 13, 1915 2,148,339 Cryan Feb. 21, 1939 2,200,720 Morin et a1. May 14, 1940 2,200,721 Marinsky et a1. May 14, 1940 FOREIGN PATENTS 328,944 Great Britain May 5, 1930