US2998631A - Preparation and use of tabs or marking labels containing yarns of partially saponified cellulose acetate - Google Patents

Description

United States Patent 2,998,631 PREPARATION AND USE OF TABS 0R MARKING LABELS CONTAINING YARNS 0F PARTIALLY SAPONIFIED CELLULOSE ACETATE Peter Meyer, London, and Victor Emmanuel Yarsley and Witold Titow, Chessington, England, assignors to Polymark Limited No Drawing. Filed Nov. 20, 1956, Ser. No. 623,313 Claims priority, application Great Britain Nov. 22, 1955 15 Claims. (Cl. 28--73) The present invention relates to improvements relating to the marking of articles and is particularly concerned with the temporary marking of textile articles by means of a tab or label which consists in part of thermoplastic material and which is caused to adhere to an article to be marked under the action of heat and pressure in the presence of a solvent, the procedure being such that the marking tab or label can be s'ebsequently peeled or removed from the article. Such marking of articles is required for example for identification purposes in the case of garments to be subjected to laundry or dry-cleaning operations and also for price marking of articles where it is desired that the marking tab or label shall be readily removable.

For temporary marking of articles it will be realised that in some circumstances difiiculties may be encountered in fulfilling all the various requirements which may be met. It is obvious that in the case of any removable tab or label the label must be capable of being substantially completely removed from the marked article without leaving any residue of material on the article, but nevertheless a comparatively firm bonding must be obtained to prevent accidental removal of the tab or label. This problem arises particularly in the case of tabs or labels for laundry or dry-cleaning marking and in this case the labels must also withstand hot detergents or solvents in some cases, while the marked articles are subjected to various handling or treating operations. Furthermore, in many cases such labels are required to carry printed identification markings which must remain clearly legible as long as the tab or label remains adherent to the article, but there must be no transfer of the printing material from which the characters are formed on the marked article.

Various proposals have heretofore been made for the use of marking tabs or labels formed in part from thermoplastic material and such methods are mostly based on the use of cellulose acetate as the thermoplastic material. By the term cellulose acetate used herein there is to be understood commercial cellulose acetate consisting mainly of secondary cellulose acetate predominantly or completely soluble in ketone solvents, such as acetone or methyl ethyl ketone. The labels are generally cut from a fabric tape including cellulose acetate yarns, such labels being applied to an article to be marked under the action of heat and pressure in the prmence of a solvent. The cellulose acetate may be in the form of staple fibre or in mono-filament or multiple-filament form; the invention may also be applied to blended yarns consisting in part of cellulose acetate.

To facilitate the removal of the tab or label it has been proposed to leave an edge portion of the tab or label unadhered to the article for example by applying the heat and pressure over less than the whole surface of the tab or label or an edge portion may be made non-adherent to the article in other ways.

With proper control in manufacture and in the means employed for applying the tabs or labels under heat and pressure to an article in the presence of a solvent, satisfactory and reliable results can be secured, but under unfavourable circumstances and on unfavourable textile articles, small but undesirable amounts of residue of cellulose acetate have been left on the marked article after removal of the tab or label therefrom, and the present invention is particularly directed to the problem of reducing such residue to the smallest possible amount so that the marked articles can for all practical purposes and under all normal operating conditions be regarded as substantially free from residue.

In accordance with the present invention this result is obtained by subjecting a cellulose acetate substance comprised by a marking tab or label or intended to be incorporated therein, to a partial saponification treatment such that at least part of the depth of the substance is afiected by such treatment, such treatment being controlled and regulated in such manner that adhesion to an article under heat and pressure in the presence of a solvent is not adversely affected to any appreciable extent while the amount of residue left on the article after the tab or label has been removed is reduced in comparison with an untreated substance.

Experience has shown that by suitable treatment of the cellulose acetate it is possible to reduce the amount of residue to a very small and substantially negligible value. In some cases this reduction in the amount of residue may be coupled with an improved adhesion compared with the untreated cellulose acetate while in other cases the adhesion may be substantially unaffected or may lie at a value which is satisfactory in practical operation. The treatment of the cellulose acetate required is however of a somewhat critical character since if the treatment is continued for an unduly long period the adhesion may be seriously reduced. It is difficult to specify the effects of the treatment of the cellulose acetate by physical criteria other than by specifying that the treatment must be such that the final result shows a noticeable reduction in the residue as compared with the untreated cellulose acetate and that the adhesion is either increased or is at least not reduced to an extent which adversely affects the usefulness of the label.

The cellulose acetate may be treated according to the invention at various stages in the production of the finished label. In the case of a fabric label including cellulose acetate yarns, the yarns may be treated before weaving the label fabric therefrom or the woven fabric or tape cut therefrom may be treated.

Whatever procedure is adopted the acetyl number of the cellulose acetate is not affected to a substantial extent and the result of the treatment is believed to be that part of the depth of each fibre or filament of the cellulose acetate yarn is subjected to partial saponification to a depth of perhaps one-third of the radius, but the present invention is not based on any particular theory as to the reasons why improved results are obtained as a result of the treatment.

Various saponifying agents can be used but in general it can be stated that hydroxides, and in particular alkali metal and alkaline with metal hydroxides, such as sodium hydroxide or barium hydroxide, or metal salts of a basic nature such as sodium carbonate or soda ash can be used. It is preferred however to use strong organic bases such as triethanolamine.

Various methods of carrying the invention into effect may be adopted, for example, a woven or knitted fabric intended for the formation of tabs or labels and formed in part from cellulose acetate yarns, may be treated by being immersed or passed through a bath containing a saponifying agent which may also include a swelling agent. The fabric is preferably woven or knitted in such manner that the cellulose acetate is exposed to a greater proportionate extent on the face which is adhered to the article to be marked than on the other face, which may carry an identification mark.

Any of the saponifying agents indicated above can be adopted and in some cases such agents also serve as their own swelling agents. The treatment can be performed at room temperature or at an elevated temperature and in general the time of treatment varies inversely with the temperature. Since the treatment may tend to be rather critical and if the time of treatment is exceeded there 15 the danger that adhesion is lost, it is preferred that a comparatively long treatment time is adopted to enable satisfactory control of the treatment to be effected. In general control is effected by determinlng the time of treatment so as to secure satisfactory final results and once said time has been determined for given treatment conditions a simple routine check from time to time 18 suflicient to ensure consistent results.

In the case of cold treatment the preferred treatment baths include triethanolamine as the saponifytng agent and cyclohexylamine as the swelling agent, the ratio of the swelling agent to the saponifying agent being an important factor in determining the treatment time. Baths of this character may require a treatment time of the order of 48 hours as will be explained in greater detail in the following examples.

If on the other hand treatment is effected at an elevated temperature such as 100 C. triethanolamine can be used without any separate swelling agent and the time of treatment may be of the order of 6 /2 hours.

Attention is directed to the fact that if the treatment is carried on for too long the result is that a tab or label including the treated cellulose acetate does not exhibit proper adhesion and it is believed that the reason for this result is that the outer skin of each cellulose acetate filament has been de-acetylated and therefore is no longer permeable to the solvent medium commonly applied to the label immediately before it is applied to the article to be marked, even under the action of heat and pressure.

Thus in one example of treatment according to the present invention applied to the treatment of a woven fabric including spaced yarns of cellulose acetate of the character disclosed in British specification Nos. 561,989, 650,- 910 and 735,236, the fabric is passed through a bath containing soda ash. The time and temperature of treatment and the concentration of the treatment bath are so chosen that the resulting fabric when used for laundry marking purposes, for example by the machines described in British specifications Nos. 644,119 and 695,708 leaves less residue on a marked article under given operating conditions than an untreated tab or label, without adhesion being impaired. In some cases the adhesion is even improved. The invention may also be applied to fabrics of similar properties produced by knitting techniques such as a Warp-knitted fabric.

In the application of other re-agents the use of triethanolamine has proved to be very convenient as it has been found that treatment is less critical than with inorganic bases and there is the further advantage of low volatility. It is found that with this material no observable reaction occurs for a certain initial period. This initial period may be of the order of one hour. After this initial period saponification proceeds relatively slowly to a point at which the adhesive properties have reached a maximum value while residue has reached a low value. After this point the adhesive properties are reduced.

It is obvious that the treatment according to the present invention is operated to give results approximating the optimum but not so close thereto that incidental changes in the working conditions result in the loss of adhesion.

Several examples of methods of carrying the present invention into effect are given below and in each case a range of treatment times is given. The difference between these times represents what may be termed the control period over which it is desirable to make tests to ascertain when the treatment of the cellulose acetate yarn has been such as to provide the required results while avoiding the fault of loss of adhesion. Examples 1 to 3 cover a. cold treatment at room temperature while Examples 4 to 6 comprise hot treatment.

In the following examples, fabrics woven (or knitted) from cotton yarns and cellulose acetate yarns as described in one of the aforesaid specifications are treated in the particular baths described, after which the fabric is slit to form the desired lengths of marking tape.

Example 1 The fabric is treated for a period between 2 and 5 minutes in a solution consisting of 0.1 N alcoholic potash. In this case the treated fabric is then dried at 70 C. without washing.

Example 2 The fabric is treated in a solution containing by weight 2.5% triethanolamine and 0.5% cyclohexylamine. The fabric is then rinsed and dried. The time of treatment ranges between 48 and 49 hours.

Example 3 The fabric is treated in a solution containing by weight 5% triethanolamine and 0.5% cyclohexylamine. The fabric is then rinsed and dried. The time of treatment ranges between 49 and 55 hours.

Example 4 The fabric is treated in a solution made up as follows, the parts being given by weight in each case:

40 parts water 3.5 parts sodium sulphate decahydrate 1.7 parts sodium carbonate anhydrous 0.3 part of a wetting agent such as Lubrol W 0.25 part n-butanol 1 part ethyl alcohol In this case the fabric is pre-treated for 10 minutes with sulphonated Lorol at 60 C. and is then rinsed and placed wet in the above treatment bath at C. The treatment time will range from 10 to 20 minutes.

Example 5 The fabric is treated at 100 C. in a solution of 10% (by weight) triethanolamine. The time of treatment ranges from to 120 minutes.

Example 6 The fabric is treated at C. in a solution of 2% (by weight) triethanolamine. The time of treatment ranges from 6 /2 to 7% hours.

In the above examples the triethanolamine used was Gemec water white Continental. Further the quality of the water used may have some influence on the operation of the process; the above examples were based on the use of a tap water having pH 7.7 and containing 235 parts per million total hardness and 65 parts per million permanent hardness. Minor modifications in the treatment time may be required according to the tension of the fabric; for instance, if the cloth is merely immersed for a lengthy period in the bath the treatment time required may be slightly different from that applying where the cloth is stretched over rollers and immersed in the bath or where the fabric is passed continuously through the bath for example in the case of continuous treatment. The fabric may also be treated by steeping in the treatment bath, wrapping or covering with waterproof material, and then leaving the fabric for the predetermined time.

It will be noted from the foregoing examples that where triethanolamine is used no additional wetting agent need be employed; at low temperatures it is preferable to include a separate swelling agent such as cyclohexylamine, but at an elevated temperature no separate addition of a swelling or softening agent is required.

Correct treatment conditions of time and temperature and other variables are established by means of tests under conditions reproducing normal working. When the correct conditions are obtained as shown by an acceptable measure of adhesion and a reduced residue on a marked article or substantially no residue, the treatment can be proceeded with and the conditions established by test repeated on a quantity basis. An independent quick check test may be based on the tensile strength of the cellulose acetate yarn when subjected locally to the action of an agent such as glacial acetic acid. For example such a test may be based on suspending a predetermined length of the yarn and applying a given weight to the lower end, thereafter applying a single drop of glacial acetic acid to the upper end of the yarn and determining the time before the yarn breaks.

After treatment in accordance with the foregoing examples, the fabric is subjected to any other treatments usual in the fabric finishing art and is then ready for the production of marking labels.

The same procedure and the foregoing examples may be applied to tapes produced from woven or knitted fabrics by slitting and to narrow woven or knitted ribbons or ribbons produced by lace-making techniques. Substantially similar methods with only minor modifications may be applied to the treatment of cellulose acetate yarns before weaving into a fabric.

Tabs or labels produced from label material treated as described above may be used for the temporary marking of articles following the application of heat and pressure to the tab or label in the presence of a solvent for cellulose acetate. Such tabs or labels remain firmly adhered to the article throughout any normal handling operations and can be withdrawn when required by pulling ofi while leaving little or no residue on the marked article, the removal being assisted by the fact that one edge of the tab or label is not adhered to the article and serves as a finger grip. This finger grip may be formed either by providing the tab or label with an edge portion free from acetate yarns or by applying heat and pressure to a part only of the tab or label.

What we claim is:

1. In a method for producing labels formed partly of cellulose acetate yarn and adapted for temporary attachment by heat and pressure to clothing articles for identification purposes during cleaning which are to be pulled from said clothing articles after cleaning, the improvement comprising partially saponifying said cellulose acetate yarns before attachment to the extent that substantially no residue remains on said article when said label is pulled therefrom and insufficient to adversely affect adhesion to said clothing articles.

2. A method as claimed in claim 1 wherein said cellulose acetate yarns are saponified by an agent selected from the group consisting of alkali metal and alkaline earth metal hydroxides, metal salts having a basic reaction, and strong organic bases.

3. A method as claimed in claim 1 wherein said cellulose acetate yarns are saponified by triethanolamine.

4. A method as claimed in claim 3 wherein said cellulose acetate yarn is saponified prior to formation of said fabric.

5. A method as claimed in claim 3 wherein said cellulose acetate yarn is saponified after formation of said fabric.

6. A method as claimed in claim 3 wherein saponification is efiected at a temperature between room temperature and C.

7. A method as claimed in claim 3 wherein saponific-ation is effected at room temperature in the presence of a swelling agent.

8. A method as claimed in claim 7 wherein said swelling agent is cyclohexylamine.

9. A method as claimed in claim 3 wherein said label is attached to said article by heat and pressure in the presence of a solvent.

10. A method as claimed in claim 9 wherein said solvent is a ketone.

11. A method as claimed in claim 3 wherein said labels are also formed partly of non-thermoplastic yarns.

12. A method as claimed in claim 11 wherein said cellulose acetate yarns are exposed to a greater extent on the fabric surface to be attached to said clothing article than on the opposed surface.

13. A label for temporary attachment by heat and pressure to clothing articles for identification purposes during cleaning which is to be pulled from said clothing articles after cleaning comprising non-thermoplastic yarns and partially saponified cellulose acetate yarns, said saponification being to the extent that substantially no residue remains on said article when said label is pulled therefrom and insuflicient to adversely affect addesion to said clothing articles.

14. A label as claimed in claim 13 wherein said cellulose acetate yarns are exposed to a greater extent on the fabric surface to be attached to said clothing article than on the opposed surface.

15. A label as claimed in claim 13 wherein said label includes an edge portion free of cellulose acetate yarns to form a non-attaching finger grip for pulling.

References Cited in the file of this patent UNITED STATES PATENTS 1,884,623 Dreyfus et a1. Oct. 25, 1932 1,897,793 Dreyfus et a1. Feb. 14, 1933 1,993,922 Dreyfus et a1. Mar. 12, 1935 2,092,006 Moncriefi Sept. 7, 1937 2,193,894 Whitehead Mar. 19, 1940 2,209,238 Sperber July 23, 1940 2,639,255 Meyer May 19, 1953 2,703,764 Vogt Mar. 8, 1955' 2,765,241 Wayne Oct. 2, 1956

Claims (1)

1. IN A METHOD FOR PRODUCING LABELS FORMED PARTLY OF CELLULOSE ACETATE YARN AND ADAPTED FOR TEMPORARY ATTACHMENT BY HEAT AND PRESSURE TO CLOTHING ARTICLES FOR IDENTIFICATION PURPOSES DURING CLEANING WHICH ARE TO BE PULLED FROM SAID CLOTHING ARTICLES AFTER CLEANING, THE IMPROVEMENT COMPRISING PARTIALLY SAPONIFYING SAID CELLULOSE ACETATE YARNS BEFORE ATTACHMENT TO THE EXTENT THAT SUBSTANTIALLY NO RESIDUE REMAINS ON SAID ARTICLE WHEN SAID LABEL IS PULLED THEREFROM AND INSUFFICIENT TO ADVERSELY AFFECT ADHESION TO SAID CLOTHING ARTICLES.