US2308593A - Knitted fabric and manufactured knitted articles - Google Patents

Description

smoothness ,is a single elongated element, but in this specie fication the term also includes a plurality of such elements in side-by-side association (e. g.

' Patented Janiapim Harold Edmund Brew, Glazebrook, Manchester, England Application September 13, 1941, Serial No. 410,699

In Great Britain November 18, 1939 I 31 cams.

This invention refers to machine-made knitted goods, including both knitted piece goods and gree of resistance to laddering (when the stitch is of a laddering type) to prevent easy damage shaped knitted articles such as articles for wear and parts thereof, for example ladies stockings, I

under-wear and the like. The invention is concerned only with goods of the type (hereinafter referred to as "the said type" or the type referred to") in which the hitting is done entirely from continuous filaments, whether nat-. ural (e. g. silk) or artificial (e. g. acetate rayon or viscose rayon) This application is a continnation in part of the application Serial No. 368,590, filed by me on December 5, 1940, entitled Knitted fabrics and manufactured knitted articles. I

The terms filament and filamentary are used herein to denote an elongated knittable element of continuous longitudinal structure, as distinct from an element which is of a longitudinaIlly-built-up structure, such as a spun-yarn. The

invention is not concerned with spun yarns made by associating short fibres together. The continuous filamentary filaments with which the invention is concerned are characterised by sub stantial uniformity of cross-section, and by of surface. In the art, a filament twisted together): and, where the ensuing description speaks of filaments as components of a composite yarn, each component will usually be a hilurality of elements associated together as'a One of the disadvantages of these filamentary knitted goods, which are fine-gauge goods, is that, with certain types of stitch there is, owing to the smooth surfaces of the filaments, a. marked susceptibility to laddering, that is a suscepti- /bility to a broken stitch in one course, releasing the engaged stitch of the next course, which in turn releases the engaged stitch of a third course,

. and so onfor successively-engaged stitches in successive courses. In the case of a ladys stocking, for instance, a loop stitch broken at the knee may cause a ladder along the length of the stocking, as far as the instep. When stockings ponent filaments are being worn they are subject to a certain' amount of lateral tension tending to straighten out the loop stitches, which tension helps in the disengagement of the successive stitches once a broken stitch occurs. Q

The use of the fine-gauge knitted goods to which this invention relates, involves two main desiderata, one being the presence of a high de-- to the goods, and the other means for satisfying these desiderata are,,to some extent, opposed to each other, in that any attempt to anchor the stitches of a knitted fabric together to resist laddering, tends, by preventing relative movement at the. points of anchorage,

to-lessen the elasticity of the fabric. The commercial failure of many of the proposals previously put forward for. preventing laddering has been due to their undue interference with they elasticity of the goods.

The object of the present invention is to provide knitted goods of the typereferred to which are of an improved character in 'that, if the stitching is of a ladderable type, laddering is prevented, or at the most is confined to a very small number of courses, without the goods having been rendered too inelastic for their normal purposes.

' According to the invention knitted goods of the type referred to are made from a composite yarn composed of at least one inert foundation filament and at least one potentially-adhesive binding filament, the filaments being twisted together with a low degree of. twist and, after knitting, the goods are subjected to treatment which will render the binding filament or filaments tacky or adhesive and will cause mutually-contacting adhesive parts to unite. The degree of twist in the composite yarn is such that there are suillcient contacts of adhesive parts with each other to prevent laddering, and such that there is sumcient relative freedom between the comof the yarn to maintain the desired .elasticity, and the nature of the treatment is such that, whilst two mutually-contacting adhesive parts will unite, one adhesive part will not as'a rule unite with an inert filament.

The invention embraces both the method of manufacture, and the manufactured goods, and

be rendered tacky or adhesive by the treatment which renders the binding filament tacky or adhesive. The expression potentially-adhesive as applied to the binding filament means capable of being rendered adhesive.

The binding filament r filaments with which the inert foundation filament is twisted may be v potentially adhesive throughout its or their whole length, or may be potentially-adhesive at some parts only. Filaments made from cellulose esters or ethers are potentially-adhesive throughout their whole length, in that the whole surface may be rendered adhesive by the action of solvents or gelatinising agents. Similarly, the whole surface of filaments coated with certain natural or synthetic resins, (such as polythene resins), or resin-forming substances may be rendered adhesive by heat. A filament potentially-adhesive at some parts only of its surface may be obtained by covering an inert filament at some parts only of its surface with a substance capable of being rendered adhesive, or by covering with a resist at some parts only the surface of a filament potentially-adhesive throughout its length.

The present invention seeks as far as possible to avoid adhesion between different parts of any one stitch loop, and between adjacent stitches in the same course. By the process of the invention adhesion normally takes place only between the binding filament of a stitch in one course and the binding filament of an inter-engaging stitch of the next course, and since the points of contact between any two such stitches in different courses are always at the base of a loop, the adhesions between the binding filament and itself will be at the base of the loop. Moreover, as the adhesions occur between the binding filament and itself, the stitches are, despite their connection capable of-some relative movement or deformation because the foundation filaments may pull away from the binding filaments to a slight extent when under stress.

The control of the position of the unions throughout the stitches, and of the relative freedom of the component filaments, is determined by regulating the degree of twist between the components of the composite yarn, and also, if the binding filament has interrupted potentiallyadhesive surface parts, by regulating the spacing of those parts from each other and by varying their size. These factors will be variable according to the size of the stitches to be made and to the degree of elasticity required in the ultimate article. In any one stitch, the chances of that stitch being united by adhesion to another will depend on the position of the potentially-adhesive part along the yarn (determin-' ing whether or not it is at the base of the loop), on the position of such part around the yarn (determining whether or not it contacts with amount of twist between the components of the yarn may be made by trial and error, but it I will be found usually to be between two and ten turns per inch.

Theoretically, if the potentially-adhesive parts are regularly spaced in the yarn, because of the twist being perfectly regular, and the stitches are of uniform size, the unions will occur in a regular series. In practice, however, it is very dimcult, if not impossible, to ensure perfect regularity in the treatment or preparation of the yarn, so that the resulting unions will be somewhat irregularly spaced in the fabric, although of the desired frequency. In most cases the yarn will be so prepared with respect to the size of the stitches to be made, that on the average not more than one contact of adhesive-forming parts will occur in any one loop.

The means selected to bring about the tacky or adhesive condition will depend to some extent on the nature of the potentially-adhesive substance in the yarn. In some cases, when that substance is one which on ageing will pass through an adhesive phase, a mere ageing will sufiice, either at atmospheric or superatmospheric pressure. In other cases, when that substance is a thermo-plastic one,the application of heat will be required, sometimes accompanied by r essure, either a mechanical pressure (e. g. ironing) or a gaseous pressure. Again, it may be necessary to apply to the knitted goods fluids which produce an adhesive state in the binding filament by acting as gelatinising agents for the adhesive-forming substances such fiuid being either in gaseous or liquid form, or themselves carried in an inert medium, any surplus being removed before final drying; or combinations of these several steps may be found advantageous. In cases where the filament consists of or carries on its surface partly-condensed resin-forming materials as the adhesive-forming substance the adhesion between the stitches may be eflectedin and by a final condensation reaction carried out in the knitted goods, for example in a closed chamber under heat and pressure. Given the substances of which the various components of the yarn are made, the selection of the best means, and the choice of fiuid agents (if used) will be made by trial and error until the adhesion can be restricted almost entirely to the binding filament and itself. The examples given below will be a guide to the right selection.

The heat treatment of the goods to bring about adhesion, when that form of treatment is selected, may be carried out in hot water when the reagents or some of them previously applied to the yarns are not readily water-soluble, or

in other suitable liquid media, the temperature the inter-engaging stitch even if at the base of v a loop), and on the corresponding positions in the inter-engaging stitch (determining whether or not two potentially-adhesive parts come into contact). The number of potential unions between the crossing yarns in the knitted fabric will increase as the number of twists per'unit length of yarn is increased, such number of unions being related to the square of the number of turns. The number of potential unions is also dependent upon the size of the knitted stitch. which is determined by the gauge or fineness of the fabric. Given the standard of elasticity required in the goods to be made, and the size of stitch required, the determination of the correct being maintained at'a sufnciently high degree to produce the required tacky-or adhesive state. In this connection, instead of the goods being subjected to a separate treatment for producing the adhesion, the adhesion may be effected during the usual dyeing and finishing processes, eitherby the mere heat treatment in those processes eifecting gelatinisation, or by one of the reagents for gelatinisation being carried in one of the finishing baths. The usual care will be taken to see that the temperatures are not raised to a degree which would be injurious to any of the substances under treatment.

In the application of the invention to the finer gauges of silk stockings, composed of 2, 3 or 4 thread thrown silk filaments, it may not be depotentially-adhesive bindingv sirable to use a fine cellulose acetate or other thermo-plastic filament as a binding filament and in such cases the necessary adhesive-forming substance would be deposited intermittently or continuously on one or more of the silk filaments e. g. by printing, spraying or other means.

According to a further feature of the invention, the gelatinising agent which is to' produce the adhesive state in the potentially-adhesive filament, instead of being applied in the form of a solvent, 'and instead of being incorporated in I the filament, is applied as an emulsion-preferably adhesive substance is governed to a large extent by the fineness or otherwise of the dispersed particles. as one of the features the selection and use of a'dis'persion whose particles are sufficiently small to effect surface gelatinisation, but large enough Accordingly, this invention includes use er the protective coating is that the consequent' increase in the diameter of a binding filament which carries such coating permits of.

greater freedom between the foundation andbinding filaments when the coating has been removed. Latices of synthetic rubbers which have a lower particle size than that of natural latex, and would thus be more suitable for coating' a fine filament thread, may be used.

to avoid penetration which would weaken the filament.

According to another feature of the present. invention, that filament which is to be potentially-adhesive (either wholly or at some parts only) is composed of or coated with rubber or a rubber-like substance, and the possible treatments for producing adhesion include the use of pressure alone, or.heat and pressure or a suitable solvent for the rubber or rubber-like substance, which will gelatinise or soften the rubber sufliciently to allow two softened parts to unite, without destroying the continuity of the filament. One of the advantages of the use of rubber and the like is that the inherent elasticity of the rubber or rubber-like substance at the points of union increases the elasticity of the goods as a whole. The coating of a filament In a convenient method of carrying out the invention, thecomposite yam comprises as the inert foundation filament, viscose rayon; and as the potentially-adhesivebinding filament, acetate rayon; the foundation filament being of larger diameter than the bindingfilament. The two components are twisted together slightly, so as Y to give for example, from two to ten turns per inch. The twisting together of the components of the composite yarn will preferably be done before the yarn is brought to the knitting machine; although his not inconceivable that knitting machines may be adapted to twist the filamerits together immediately prior to knitting. In any case, it is necessary to insert only suflicient twist in the composite yamto provide enough binding places to give the desired degree of anti-laddering effect and to maintain a de-.

sirable elasticity. More twist than this, by in-' troducing too many bindings, and by associating the binding filament too tightly with the foundation filament, will be liable to reduce the elasticity of the fabric unduly.

It is probable that with some methods of treatment a slight shrinkage will occur in the length may be done by means of an organic solvent or by means of latex, or other suitable dispersion. This feature of the invention may be further characterized in that the rubber or like substance is deposited on an inert filament by mak-- ing use of opposite charges on the filament and rubber etc. The filament on which the rubber is to be deposited is treated before knitting with a cation substance at the parts which are to be made potntially-adhesiveand the filament is then passed through a latex bath, with the result that rubber is deposited where the cation" of the binding filament, and in order to counteract this and thus preserve the elasticity of the fabric, it may be desirable to have. a greater length of the binding filament than of the inert foundation filament per unit length of; composite yarn. This may be accomplished by havingdifferent tensions for the different components' during folding and twisting together, and/or by twisting (or untwisting) the components themselves (or one of them) prior to or during twisting together, the separate twisting or untwisting of the components being to the same or to different degrees, and in the same or in different directions. It would be possible, for instance, so, to prepare the components that in twisting them together the inert foundation filament would be still further twisted, whilse the binding fi ament would be untwisted, thus providing a greater length of theshrinkable component than of the other component, in any given length of the composite yarn, but not sumciently to interfere with the knitting properties oi the yarn.

The-knitted articles of the invention may be.

I regarded as formed of two fabrics, the respec substance is-present. Alternatively, an anion;

substance may be used when the dispersed particles are of the opposite charge. a tacky con In order to produce'and preserve a dition in the rubber, any suitable softeners or. retarders may be incorporated in the mix, and in order that the tackiness shall not interferewith the twisting of the filaments (when a composite yarn is to=be used) or the knitting processes, a further coating of a water-soluble pro-' tection may be applied to the'filam'ent. This coating would be removed by being dissolved in one of the treatment baths, to allow the contacting rubber parts to unite.

An incidental advantage accruing from the tive threads of which are intertwined, and one only of which is keyed to itself at points of crossing. Ifthe degree of twist, the separate tensions during the folding of the inert and binding filaments, and the tension of the composite yarn during knitting are adjusted to the opt mum, a certain amount of relative movement is possible between the two fabrics, and if the finishing treatment is appropriately selected such relative movement is maintained, thus preserving to a large extent the elasticity of the material as a whole. This effect may be enhanced by giving to thecompound fabric a finishing treatment with a suitable lubricant. The

binding filament being mainly for the introduction of binding places, maybe as fine as conveniently possible consistent with its havin sufficient strength for its purpose,

In a fabric made according to this invention, the unions at the crossed adhesive parts are within the thickness of the fabric, between the crossed yarns.

When the adhesive or tacky state is brought about by the application of a gelatinising agent or solvent, it is necessary to control the action so as to avoid any adverse efiect on the physical properties of the yarn, and for this purpose a diluent may be used. Such diluent may be one that is appreciably more volatile than the gelatinising agent. Where the degree of gelatinisation is controlled by the application of the gelatinising agent and diluent for a short period of time and by the rapid removal (say by evaporation, or washing off or further dilution) of the diluent, the volatility of this latter need riot be so high. When a more volatile diluent is used the gelatinisation and adhesion occur during evaporation of the agent and diluent.

In cases where the binding filament is likely to shrink and become brittle under the influenceof a volatile gelatinising agent, and where this tendency cannot be conveniently or sufiiciently counteracted by regulating tensions and twists as above mentioned, a less volatile solvent may be used as the gelatinising agent or as an addition to the volatile genatinising agent, which less volatile solvent will, when it remains in the binding filament, also serve as a plasticiser to counteract such tendency to brittleness. This less volatile solvent or plasticiser if not subsequently removed, should be stable under normal conditions insoluble in water, and unafiected by hot detergents, and should be non-toxic and nonirritant.

Preferably also, the plasticiser should be colourless and odourless. The terms volatile" and less volatile as used herein refer to volatility at normal room temperatures in open atmosphere.

The binding filament may be formed from cellulose esters, such as cellulose acetate or cellulose nitrate; the mixed cellulose esters (such as cellulose aceto propionate) or from cellulose ethers (such as benzyl cellulose or ethyl cellulose). Further, synthetic filaments of other materials may be employed as the binding filament, for example, the polyamide and vinyl resins; or a filment with a smooth sheath or coating or impregnation of cellulose acetate, or other cellulose derivative, or other potentially-adhesive substance on a core of non-reactable substance such as viscose. Natural and synthetic rubber substances may also be used as the adhesive-forming substance if in filamentary form or carried. by a non-adhesive filament. In all these 4 cases, the selected gelatinising agent will be suitable to the substance used in or for the auxiliary or binding filament.

Examples of agents for effecting gelatinisatlon and comprising solvents of high and low volatility, selection from which will be determined by the nature of the adhesive-forming substance to be gelatinised are:

(c) The ketones, both simple and mixed (such as methyl ethyl ketone and di-acetone alcohol);

(d) The aliphatic and aromatic esters, including those derived from simple esters by the inclusion of substituent groups in the molecule (such as ethyl acetate, ethyl aceto-acetate, diethyl carbonate, glyceryl tri-acetate and dimethyl glycol phthalate. Di-methyl phthalate has been found particularly useful for cellulose acetate);

(e) The arylsulphonamides (such sulphonamide): and

(f) Any suitable mixture of any of the above. Agents which have a strong solvent or dispersing action on the material of the binding filament are not suitable for use alone as gelatinisers. The aim of the treatment is to produce in the binding filament an adhesive state of such degree that union occurs only between parts of the binding filament in contact with each other, and not *between the binding filament and the inert foundation filament. Thus. acetone and acetic acid are not suitable alone as gelatinisers for cellulose esters. Where cellulose acetate forms the potentially-adhesive'substance, di-methly phthalate gives the range of adhesiveness required to achieve the object of the invention.

Some of thegelatinising agents included above are not effective when used alone, but have a gelatinising effect when mixed with another nonsolvent. Such mixtures have advantages in that the solvent or gelatinising action is more gentle and is more easily controlled. An example of such a mixture. suitable for use with cellulose acetate, is ethyl alcohol with di-ethyl carbonate or butyl formate. Again, some of the agents specified are non-solvent at ordinary temperatures but become effective on the temperature being raised. For example: ethylene glycol mono ethyl ether produces no adhesion in cellulose acetate at normal temperatures but will do so at say 60 C. Other similar examples are n-propyl and iso-propyl alcohols and acetates and methyl amyl ketone.

Therefore, the term gelatinizing agent as used herein includes those agents which per se are either too active or insumciently active but which,

lulose acetate, the gelatinising agent selected will depend to someextent on the acetyl content of the acetate used, as some of the solvents above- I named are more efi'ective with some types of ace- (a) The aliphatic and aromatic hydrocarbons and their halogen derivatives (such as petroleum benzine, benzene, methylene chloride and monochlorbenzene) (b) The alkyl and aryl alcohols, including the glycols. and substituted derivatives (such as methyl alcohol, benzyl alcohol, ethylene glycol tate than with others.

Examples of diluents suitable for use with gelatinising agents for cellulose acetate, and which otherwise would be too strong and injure the acetate are, the aliphatic alcohols and ethers (such as ethyl alcohol and ethyl ether), and the aliphatic and aromatic hydrocarbons and certain of their chlorinated derivatives (such as pentane, benzene and carbon-tetra-chloride).

If the gelatinising agent consists of or'includes a substance not readily volatilised at moderate temperatures, such substance may be removed from the inert foundation filament, but not completely from the binding filament, by washing oil. In this case, selective action is obtained as a result of preferential absorption by the binding filament. The selective action may be increased as p-toluene ing adhesive parts.

pressing is usually between 110 C. and 150 (3.,

by using in the washing process a relatively poor .solvent for the less volatile substance and a short period of treatment. For example, when an alkyl phthalate has been used, petroleum ether and benzene are useful as solvents to remove the alkyl.

phthalate from the mainyarn whilst not removing it altogether from the binding yarn.

In the accompanying drawing: 1

Fig. 1 is an enlarged face viewof a piece of knitted fabric according to this invention, made with a composite yarn having an inert founde tion filament and a potentially-adhesive binding I filament. twisted together, in which thepitchof' the twist is greater thanthe total length of the complete stitch; I

Fig. 2 is a like view, in which the pitch of twist is equal to the total length of one complete stitch; Fig. 3 is a like view, of a fabric in which the components of the composite yarn are not twisted together, and in which thereforethere is a possibility of the number of unions being 1111, or at the most being very small; and

and a suitable time is A minute or thereabouts; a suitable range of pressure is that adopted in normal hosiery finishing. All the optima for these factors may be found readily by trial. In order to prevent one side of the stocking sticking to the other side during the pressing operation it is necessary to insert a shielding material in the stocking, for example a wooden form, as in the known finishing art.

' In this mode of treatment, instead of a mechanical pressure being employed, ,the goods may-.Ebe subjected to agaseous pressure in a closed chamber and at an elevated temperature.

Figs. 4 and 5 are diagrams to illustrate how the A other filamentary natural. or artificial material not potentially-adhesive in relation to themode of treatment to be selected, and a filamentary binding element 2 twisted with the inert founda- In a modification of this mode of treatment,

instead of a non-volatile solvent being applied to the yarn by immersing the goods in a bath containing the solvent, thenon-volatile solvent is incorporated in the binding filament itself during itsm-anufacture. In such case, after knit-H ting, the goods are merely subjected to,a heat and pressure treatment in' either of the ways referred to above.

In another mode of pperation, after the appli cation ofthe non-volatile solvent to the knitted. goods, the goodsare passed to the dye bath the heat of which eifects gelatinisation. Alternatively, a non-volatile gelatinising agent is carried in tion filament Lthe element 2 being of cellulose acetate, or of ether rayon, or of locally hydroiised acetate, or being an acetyla'ted filament or other filamentary adhesive-forming substance, the

' selection being such that the subsequent treatment to bring about an adhesive condition will not aifect the inert foundation element I. The type of fabric shown is a simple, single-ply knit having loop stitches A and sinker stitches B, such as might be produced on an ordinary circular stocking-knitting machine. It will be observed that at the point 3, the binding element 2 crosses itself in contact, such point 3, being at the base of a loop A, and that these contacts occur at more or less random points but with relative frequency. As shown in Fig. 2 the points of contact are more numerous, and occur consistently at the same parts of the stitches. This regularity is difiicult to achieveand moreover the greater number of unions, whilst increasing the reinforcement ofthe' fabric, may render the fabric too rigid for some purposes e. g. for stockings.

In both cases shown, the main fabric which is formed from the inert foundation filament [has no unions in it, and therefore is elastically free. Should a stitch break at any point, whether in one element only or in both, laddering will occur only so far as the'nearest points of adhesion of the binding filament.

In a preferred mode of carrying out the invention, for the manufacture -of anti-iaddering stock- 9 ings, the stockings are knitted with a composite yarn such as is shown in Fig. l, in which the binding filament is cellulose acetate, and the inert foundation filament l is viscose. After knitting,-

the stockings are first immersed in a bath containing a non-volatile gelatinising agent such as dimethyl phthalate in benzene, are then drained,- dried, and finally subjected to a hot-pressing or ironing treatment which causes union of contact- A suitable temperature for one of the normal finishing baths, and, where the temperature of that bath is not-high enough itself to bring about gelatinisation the usual drying processes which follow will give the required heat treatment to bring about the desired adhesion.

In another convenient mode of carrying out the invention, also for the manufacture of antiladdering stockings, the stockings are knitted with a composite yarn such as is shown in Fig. 1 and are then immersed in a sufiiciently-strong bath'of a volatile gelatinisingagent, such as ethyl acetate, with or without a diluent such as pentane, and with or without a l ss volatile solvent such as di-n ethyl phthalate to act as a plasticiser, and are then dried at room temperature and pressure, or thereabouts, gelatinis'ation occurring-in the bath or during evaporation accord ing to the nature of the agent employed.

In another modification, the goods, instead of being immersed in a volatile gelatinising'reagent, are exposed to a vapour, for example, chloroform, or methylene chloride vapour, preferably at a varied temperature and pressure.

In cases where two layers of a stocking or of other tubularor folded articles would otherwise be in contact whilst adhesion is being brought about, and would become united, a

shielding element will be'inserted to prevent the adjacent layers of fabric adhering to each other,

as described above.

This protection of the tubular goods from selfj contact may not always be necessary; for example it may not be necessary when' the adhesion is brought about whilst the goods are inan aqueous bath. It is believed that during and after the immersion of the goods in an aqueous gelatinising bath, absorption of water causes some swelling action as a preliminary to and distinct from gelatinisation, and that where such swelling occurs in two contacting binding filaments, withinthe fabric, the contact pressure is sufficient to guarantee at those points a union which does not take place elsewhere.

It may be foundthat, after some modes of treatment, the fabric'has acquired a slight stiffness which is doe to mere matting or incipient cohesion, between theyarns at points other than the main binding places where more or less complete union has occurred. This stifiness may be removed, and at the same time the yarn may be somewhat softened, by subjecting the fabric to an after-treatment which will break down such incipient connections without impairing the main unions. The after-treatment may comprise the application of a warm weak soap solution, or even of warm water alone, or of other media, and in some cases may comprise or include a light mechanical working.

Referring now to Fig. 3, it will be observed that in the fabric shown there are no unions. The elements I and 2 in this case are not twisted together and there is a probability that one of the elements will be thrown consistently to the outside of the fabric in the knitting process. If and where this occurs the anti-laddering effect is absent, for which reason it is necessary to twist the elements together, if only slightly.

In Fig. 4 unit lengths of two portions of comfabric was then subjected to the after-treatment in soap solution as in the preceding example.

ample 1 but to the binding filament of which that amount of dimethyl phthalate had been applied pound yarn are shown each having two twists. It

will be obvious that, potentially, each of the parts X in one unit may unite with either of the parts X in the other unit, making four possibilities in all. In Fig. 5 equal units of compound yarn are shown, each having four twists. Here also, each of the parts X in one unit may unite with any one of the parts X in the other unit, making sixteen possibilities in all. The number of actual unions taking place will be roughly proportional to the number of possibilities oifered, and the number of actual unions will vary substantially as the square of the number of twists per unit length of the compound yarn.

The following are examples of the carrying out of the invention, the fabric in all cases being brought to a clean scoured condition before the treatment begins:

Example 1.-The fabric was made from a composite yarn having a basic filamentary component of viscose or of thrown silk of 60 or '75 denier with 2 turns Z twist per inch, and an auxiliary filamentary component of cellulose acetate of 15 denier with 2 turns Z twist per 1", the two components being twisted together so as to have 5-6 turns S twist per 1". The fabric was knitted with 48 wales per 1" and with 48 courses per 1".

The fabric was immersed for-5 minutes in a bath made up of Parts by volume Di-methyl phthalate 4-6 Benzene 96-94 at a normal temperature and pressure, and then dried as by squeezing and evaporation but so that the air-dry fabric contained about 10-15% by weight of the di-methyl phthalate. The fab ric was then subjected to a hot pressing treatment for A minute or thereabouts at 120 C. during which gelatinisation and adhesion took place, and to an after-treatment of 10 minutes duration at 40-50 C. in a to 1% soap solustead the fabric was subjected to a heat and pressure treatment by being heated .in a closed chamber for a short period at 140 C. under a gaseous pressure of 80 lbs. per square inch. The

Parts by volume Ethyl acetate 30 -35 Pentahe 62 68V: Di-ethylphthalate 1 /2- 3 at normal temperature and pressure, and the surplus liquor then removed as by centrifuging, the diluent (pentane) and the remaining volatile solvent (ethyl acetate) then being allowed to evaporate slowly. Adhesion took place during evaporation. The major proportion of the nonvolatile solvent (di-ethyl phthalate) was then removed from the main filament by a short washing-oif treatment with petroleum ether, some of it being retained in the binding filament by preferential absorption. An after-treatment in soap solution was then carried out as in Example 1, and the fabric finally dried.

Example 5.A fabric as used for Example 1 was immersed in the following bath, and the treatment continued as in Example 4;

Example 6.-A fabric as used for Example 1 was immersed in the following bath and the treatment continued as in Example 4:

Parts by volume Butyl formate 50 Alcohol 50 Example 7.A fabric as usedfor Example 1 was exposed to an atmosphere of chloroform vapour for an hour at normal temperature and pressure, during which exposure the adhesion took place. and the fabric was then subjected to the after-treatment as in Example 1. This example may be modified by the dilution of the chloroform vapour with air or an inert gas, and/or by the presence of a plasticiser (such as di-meth'yl phthalate) in or on the binding yarn. In all cases the treatment could be accelerated by raisin; the temperature and/or by raising the pressure of the gaseous reagent.

Example 8.--A fabric as used for Example 1 was immersed for 30 seconds in a bath made up of at normal temuerature and pressure, during which immersion the adhesion took place, the surplus liquor was then removed, and the remainder allowed to evaporate slowly, after which an after-treatment was carried out as in Example '1.

, lant or squeezing operation for the removal of 2,808,593 A y Example 9.- Knitted goods were made mm plus liquor, but can readily ascertained by trial thrown silk yarn composed of three silk filaments twisted together with turns per 1'', one of which, before twisting, had been coated with a mixture containing cellulose acetateand dimethyl phthalate, carried in a volatile medium,

- the coating being in lengths of A" spaced apart at intervals. Such a mixture may also contain softeners and/or a lubricant to assist knitting as in known practice. After knitting the andjerror. 1;.

' Example 11.-A real s ilk filament having a slight twist and in a de gllmme d state,'has a layer of a naturalor synthetic rubber applied to it from an organic solution of'the rubber say in benzene orin solvent naphtha, or'from-latex or other dispersion. The filament is then incorporatgoods were heat treated according to Example 2 to produce the desired adhesion.

Example 10.--A knitted fabric made from a composite yarn having two components, the .potentially-adhesive one being cellulose acetate and the other being silk or viscose, and having five or six turns per inch twistbetween the two components, was padded with the following emulsion for 5 minutes at room temperature, the fabric,

first being brought to a clean scoured condition:

Di-methyl phthalate 5- -7 parts by volume Emulsifying agent (accordmg to the particular agents used) 2-5 parts by volume Water Made up to. 100 parts by volume Liquor/goods ratio :1

Alternatively, the emulsion may be diluted to, about 1% by weight of di-methyl phthalate and the goods impregnated for about minutes when they will more or less completely exhaust the bath. The dried fabric should contain 5 to 10% by weight of di-methyl phthalate' after treatment.-

Examples of emulsifying agent are colloidal clay (bentonite), and sulphonated oil, whilst alternatives to the di-methyl phthalateare butylene glycol diacetate, methyl glycol phthalate and butyl tartrate, suitable variations inquantity being made. The emulsion bath should be well agitated as otherwise there may be some tendency to sedimentation of the emulsified particles, if they are of relatively high specific gravity. Hosiery dyeing machines of the rotating drum type are suitable. ,After padding, the material is centrifuged to remove the surplus emulsion and the hose'is then pressed on boards for about 1 minute at 120 C. or thereabouts, when adhesion-or the cellulose acetate occurs. The material may be pressed in the wet state after centrifuging or after drying at a moderate temperature (30-40 C.). When the former mode is adopted, the concentrations of the phthalate may be reduced to about half those indicated, but local partial drying is to be avoided. After pressing the hose should be given a .1045 minute treatment in warm water or dilute soapor emulsifying agent solution at say 40-50 C. During this washingoff th gelatinising agent is redispersed and may be subsequently recovered. Finally the-hose may be dyed and finished as usual. The main advantages of the emulsion application are that no special is required as-with organic solvents, and the gelatinising agent is easily and cheaply recovered. Further a reduced amount of the ge- -latiniser is required. The stockings (instead of in bags in a drum machine) may timum results will depend on the degree to which the bath will be exhausted by the treatment of the goods and on the eiliciency of the centrifuging the sured as a binding filament in a composite yarn, and

at a later stage the rubber is rendered adhesive by the application of'solvents, or'by chemical action,.or by heat and pressure, or other suitable means. When the filament is not required to be potentially adhesive along iitswhole length, certain parts of it are coated'with' a resist or protector before the twistingoperation, to isolate thosexparts 'fromthe solvent in the subsequent treatment. The rubber may be compounded with all or some of the ingredients'flnecessary for effecting vulcanisationing the knitted article by heat or by a cold cure: or some of these agents could be dispersed or dissolvedv in a bath for treatment of the knitted fabric before, during or after dyeing. The principal necessary constituents would consist of sulphur, an. activating agent such as zinc oxide or zinccarbonate, and an accelera-* tor such as salts of substituted dith'io'carba'mic or xanthic acids or guanidine derivatives.

If an accelerator is compounded with the rubber before application to the filament, substances tending to self-vulcanisation would have to be avoided. About 1.% of sulphur and zinc oxide could be compounded in the rubber or latex mix, and an accelerator such as diethylammom'um diethyldithiocarbamate or sodium dibutyldithiocarbamate applied from an aqueous bath at a later stage after the yarn "and anti-oxidant may require to be incorporated has been knitted. A softener with the rubber, the former to give a lower modulus .of elasticity, and give softness and flexibility,

examples being mineral oil, paraihn wax, glycerin,

palm oil, and stearic acid. v

In the,cas e of latex applications the silk or rayon or other filaments may be p e-treated with a wetting agent, or with ammonia or a cationic soap (such as cetyl pyridinium bromide) to assist in the deposition of the rubber onto the filament, or a coagulating agent such as ammonium persulphate or sodium silico fluoride may be used for thatpurpose.

Substances such as starches, dextrins, resins,

gums, gelatine or casein may be added to maintain the tacky condition of the rubber after drying, until adhesion is required at mutually contacting parts in the fabric, of the fact that such rubber films will adhere to themselves, but not to other-surfaces. To prevent such tackiness from adversely afiecting the knitting and winding of the yarn it may be necessary to apply over the rubber film a waterremovable protective coating. Such a coating would assist in maintaining relativeireedom between rubber-coated and untreated components of the composite thread, by increased diameter to the coated filament. Examples of coating are starch, or dextrin, chalk, glycerine or a soluble oil.

Example 12.-A cation soap alone may be ,ap-f

plied to one or more components '(but not all) of a multifold silk thread, the component being padded before twistingwith an aqueous solution of cetyl pyridinium bromide, containing 5% or less of the soap. This component should beef a relatively low twist and be degumined. It is then twisted with other untreated threads in thereby making use giving a temporari y the gum, with from to 20 turns per inch in the doubling. After knitting the material is immersed in a dilute latex of say 5% to 20% rubber content, for about 30 minutes at room temperature, during which time the negatively charged latex particles will be deposited on the positively charged thread where it carries the cationic soap, but not to any appreciable extent, on the untreated threads, which last may-even be treated with an agent to prevent wetting-out by the latex. The material is then washed and dried and during drying the deposited latex will produce adhesion where the padded yarns cross in mutual contact. The amount of rubber deposited can be controlled by adjusting the amount of cationic soap applied to the thread in the pretreatment, and by varying the concentration of the latex bath. Instead of a cation soap, 8. oo-

4 heating to bn'ng agulant maybe used, such as ammonium persulphate or sodium silico fluoride. A vulcanised latex may be used. If an unvulcanised latex is used the fabric could be vulcanised with the ingredients carried in one of the baths.

In any of the foregoing xamples where an immersion treatment is used, the immersion may be carried out under super-atmospheric pressure.

The conditions of evaporation of the solvent and diluent from the fabric may have considerable efiect on the binding filament. The evaporation of the volatile solvents should preferably take place at a temperature above normal room temperature, and in an atmosphere containing the solvent in vapour form, and if necessary with the material undergoing a slow uniform movement. i

The treatment of goods to provide adhesion, will usually be carried out with the goods under a tension which will assist in preventing shrinkage of the binding component and also separate the loop structure.

As an alternative to the after-treatment with soap solution, when the adhesive-forming subhosiery finishing being twisted together with a low degree of twist: and wherein, after knitting, the goods are subjected to a treatment which will produce the adhesive state in the potenially-adhesive filament such as to bring about union between that filament and itself only, at points where it crosses itself in contact.

2. Method according to claim 1, wherein the potentially-adhesive parts are rendered adhesive by heating, and pressure is applied during the about union.

3. Method according to claim 1, wherein the potentially-adhesive parts are rendered adhesive by the application of a gelatinising agent.

4. The method according to claim 1, wherein the binding filament is potentially-adhesive by reason of synthetic-resin-forming substances being present in its surface, the adhesive state being producible during a condensation of the resin; and whereinthe knitted goods are subjected to heat and pressure to condense the resin and thereby produce union at points where condensation occurs in the meeting surfaces of two binding filaments crossing in contact.

5. The method of manufacture of knitted goods, wherein the goods are knitted from a composite yarn which is composed of filaments'which are not potentially-adhesive and at least one of which is provided with a coating of a potentiallyadhesive substance, the filaments being twisted together; and wherein, after knitting, the postance is cellulose acetate, an after-treatment with an aqueous solution of a swelling agent for cellulose acetate (such as acetone or di-acetone alcohol) may be used.

In the manufacture of such articles as stockings, the composite yarn may 'if desired be employed for a certain proportion only of the courses, and some other yarn be employed for the other courses. In such a case it may be necessary to use an equivalent count for that other yarn, so that there will be no noticeable ringing or like marking of the finished article.

The gelatinising process may, n the case of dyed goods, be carried out before or after, or during dyeing. It is possible, by using this process, and particularly with the soaping as an after-treatment to give to rayon material some of the handle and appearance ofreal silk.

Whilst the invention has been described as related to the prevention or reduction of laddering', it is found also that the resulting knitted goods have an increased resistance to distortion, making them more amenable to mechanical processing, and having an increased resistance to curling and fraying.

What I claim is: V

1. The method of manufacture of knitted goods wherein the goods are knitted from a composite yarn which is composed of at least one potentially-adhesive filament and at least one filament not potentially-adhesive, the filaments tentially-adhesive parts are rendered adhesive by heating, and pressure is applied during the heating to bring about union between only adhesive parts crossing in contact.

6. The method according to claim 5 wherein the potentially-adhesive substance is a rubber substance.

7. The method according to claim 5 wherein the filaments are silk threads and the potentially-adhesive substance is a rubber substance.

8. Method according to'claim 1, wherein the potentially-adhesive filament contains within itself a thermo-responsive gelatinising agent and is rendered adhesive by heating, and pressure is 1 applied during the heating to bring about union.

9. Method according. to claim 1, wherein the potentially-adhesive filament is a cellulose acetate filament of finer denier than the non-adhesive filaments, and contains within itself from 5% to 10% of di-methyl phthalate, such filament being rendered adhesive by heating, and pressure being applied during the heating to bringabout unio 10. The method of manufacture of knitted goods, wherein the goods are knitted from a composite yarn which is composed of filaments which are not potentially-adhesive and at least one of which has a coating of a potentially-adhesive substance, the filaments being twisted together; and wherein, after knitting, the potentially-adhesive parts are rendered adhesive by the application of a gelatinising agent-and union is brought about between only adhesive parts crossing in contact.

11. The method according to claim 1 wherein each potentially-adhesive filament is composed of a potentially-adhesive substance and is of finer denier than the non-adhesive filaments, and wherein, after knitting, the potentially-adhesive filaments are rendered adhesive by the application of a gelatinising agent.

12. The method according to claim 1 wherein each potentially-adhesive filament is composed of a potentially-adhesive substance, and wherein after knitting, the potentially-adhesive filaments are rendered adhesive by the application of gelatinising agents in the form of volatile solvents with which are mixed less-volatile solvents to serve as plasticisers for the potentially-adhesive filaments.

13. The method according to claim 1 wherein each potentially-adhesive filament is composed of a potentially-adhesive substance, and wherein afterknitting, the potentially-adhesive filaments are rendered adhesive by the application of gelatinising agents in the form of volatile solvents with which are mixed less-volatile solvents to serve as plasticisers for the potentially-am hesive filaments, and also including the step of removing the less volatile solvents from the nonadhesive filaments but not completely from the potentially-adhesive filament by the use of a weak solvent for the less-volatile solvent through a short period. and by relying on the preferential absorption of the potentially-adhesive filament for the less-volatile solvent.

' 14. The manufacture of anti-laddering knitted goods wherein the goods are knitted from a composite yarn having a filamentous silk or viscosefoundation component and a filamentous cellulose acetate auxiliary component of finer denier, the two components having been twisted together: and wherein after knitting the goods are first immersed in a bath containing ethyl acetate pentane and di-methyl phthalate, are then dried,

and are finally given an after-treatment in a weak soap solution.

15. Method according to claim 1, wherein the I potentially-adhesive parts are rendered adhesive by theapplication of an emulsified gelatinising agent.

16. Methodaccording to claim 1, wherein the potentially-adhesive parts are rendered adhesive by the application-of, an emulsified gelatmere matting at points. away from and without impairing the main unions.

17. The method of manufacture of knitted goods wherein the goods are knitted from a composite yarn composed of at least one filament not potentially-adhesive and at least one filament of cellulose acetate, the filaments being twisted together; and wherein after knitting, the goods are treated in an aqueous emulsion of di-methyl phthalate and dried so as to contain from 5% to 10% di-methyl phthalate, and finally heat treated to gelatinise the acetate and subjected to pressure during heating to cause union between the acetate and itself where it crosses itself in contact. 1

18. The method of manufacture goods, wherein the goods are knitted from a composite yarn which is composed of filaments of knitted which are not potentially-adhesive and at least one of which has a coating of a potentially-adhesive substance, the filaments being twisted to gether; and wherein, after knitting, the potentially-adhesive parts are rendered adhesive by the application of a gelatinising agent, the potentially-adhesive coating being composed of a gelatinisable rubber substance and union is brought about between only adhesive parts crossing in contact.

19. The method of manufacture of knitted goods, wherein the goods are knitted from a composite yarn which is composed of filaments which are notpotentially-adhesiveand at least one of which has a coating of a potentially-ad hesive substance, the filaments being twisted together; and wherein, after knitting,- the potenitally-adhesive parts are rendered adhesive by the application of a gelatinising agent, the potentially-adhesive coating being composed of a gelatinisable synthetic resin and union is brought about between only adhesive parts crossing in contact.

20. The method of manufacture of knitted goods, wherein'the goods are knitted from a muiti-thread thrown silk yarn one of the threads of which is coated with a gelatinisable rubber substance, and wherein after knitting, the coating is rendered adhesive by the application of a gelatinising agent and pressure is applied to subjected to a treatment which will produce the adhesive state in the potentiallyeadhesive, filament such as to bring about union between that filament and itself only, at points where it'crosses itself in contact; wherein prior to being twisted together the components are each twisted sepa-. rately; and wherein the directions of twist are such that when the components are being twisted together the inert component is still further twisted whilst the potentially-adhesive component is slightly untwisted.

22. In the manufacture of knitted goods wherein adhesive unionbetween one component of a composite yarn and itself is produced at points where such component crosses itself incontact; the step of applying a resist at points in the length of that component, to prevent grouping of the unions in the fabric.

2 3. A knitted article made from a composite yarn comprising at least one potentially-adhesive filament and at least one filament not poten tially-adhesive, the filaments being twisted together with a low degree of twist and the potentially-adhesive filament having been caused to adhesive parts being united at spaced portions of the loops of said knitted articles, the inert filaments of each bundle being unattached even at the points of contact with said adhesive filament.

25. .A knitted article comprising composite fiiament bundles eacnhaving at least one inert foundation filament and at least one potentially-adhesive binding filament, said filaments being twisted together with a low degree of twist, mutually-contacting adhesive parts being united at spaced portions of the loops of said knitted article, the inert filaments of each bundle being unattached even atthe points of contact with said adhesive filament.

-.-26. A knitted article comprising composite filament bundles each having at least one inert foundation filament and at least one potentiallyadhesive binding filament, said filaments being twisted together with a low degree of twist, mutually-contacting adhesive parts being united at spaced portions of the loops of said knitted articles, the inert filaments of each bundle being unattached even at the points of contact with said adhesive filament, the number of said contacting parts being sufiicient to prevent substantial laddering whil maintaining suficient relative freedom between filaments to maintain elasticity of said article.

27. A knitted article comprising composite filament bundles each having at least one inert foundation filament and at least one potentially-adhesive binding filament, said filaments being twisted together with a low degree of twist, each bundle having 2-4 filaments and the number of twists being 2-10 per inch, mutually contacting adhesive parts being united at spaced portions of the loops of said knitted article, the inert filaments of each bundle being unattached even at the points of contact with said adhesive filament.

28. The method of producing knitted goods having a high resistance to laddering, which comprises the use of a yarn made of separate filaments twisted together, and the causing of one of the filaments to stick to itself at crossing contacts without causing it to stick to the other filaments.

29. A knitted article made from a composite yarn comprising at least one potentially-adhesive thread and at least one thread not potentially-adhesive, the latter being inert so as to be incapable of adhesion to said first thread. said first thread being twisted with said latter thread'with a low degree of twist, said first thread having been caused to adhere to itself only, at points where it crosses itself in contact.

30. A knitted article made from a composite yarn comprising at least one potentially-adhesive thread and at least one thread not potentially-adhesive, the latter being inert so as to be incapable of adhesion to said first thread, said first thread being twisted with said latter thread with a low degree of twist. the pitch of the twist being greater than the total length of one stitch, said first thread having been caused to adhere to itself only, at points where it crosses itself in contact.

31. A knitted article made from a composite yarn comprising at least one potentially-adhesive thread and at least one thread not potentially-adhesive, the latter being inert so as to b incapable of adhesion to said first thread, said first thread being twisted with said latter thread with a low degree of twist, said first thread having at' least one component which is potentiallyadhesive, said first thread having been caused to adhere to itself only, at points where it crosses itself in contact.

HAROLD EDMUND BREW.

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