GB2100767A

GB2100767A - Embossing process

Info

Publication number: GB2100767A
Application number: GB08119188A
Authority: GB
Inventors: Stephen Alfred Myers
Original assignee: Wool Development International Ltd
Current assignee: Wool Development International Ltd
Priority date: 1981-06-22
Filing date: 1981-06-22
Publication date: 1983-01-06

Abstract

The invention provides a process for embossing a fabric containing keratinous fibres, wherein a predetermined area of fabric is printed with a composition comprising a stabilizing agent for the keratinous fibres and a thickening agent, the treated material is dried and embossed and the embossed material is then washed to remove the thickening agent. Preferably the stabilizing agent is a mixture of a reducing agent for keratinous fibres and a curable resin capable of imparting shrink resistance to keratinous fibres.

Description

SPECIFICATION Embossing process This invention relates to a process of embossing fabrics containing keratinous, and especially wool, fibres and to the production of articles of clothing embossed by the process.

Various processes are known for the embossing of fabrics. It has for example been proposed to treat fabrics with a thermoplastic or thermosetting resin and then subject the treated material to heat and pressure with a die profiled with a desired embossing pattern. Conventional methods of embossing fabrics have certain disadvantages when applied to fabrics which are to be used for clothing. The embossing process, may, for example, cause the fabric to acquire a harsh handle or the pattern may have poor resistance to washing especially when the fabric is washed in a domestic washing machine.

Conventional processes also cannot be applied satisfactorily to ready-made garments. Accordingly, it is the practice to emboss pieces of fabric which are then assembled into a garment, for example, a pullover, by a cut and sew process which is both laborious and costly.

It has now been discovered that many of the disadvantages of known embossing processes can be alleviated by a process in which a fabric is first printed with a printing paste containing a stabilising agent for the wool fibres and then subjecting the fabric to embossing and then to a certain sequence of finishing steps described below.

Accordingly, this invention comprises a process of embossing a fabric containing keratinous fibres wherein a predetermined area of the fabric is printed with composition comprising a stabilising agent for the keratinous fibres and a thickening agent and thereafter the treated material is dried and embossed and the embossed material is then washed to remove the thickening agent.

The process can be applied to fabrics containing a variety of keratinous fibres, for example, angora wool, alpaca and mohair. The use of sheep's wool, more especially lambswool or botany wool, is preferred. The fabric consists entirely, or of at least a major proportion, of keratinous fibres. The fabric can be woven, non-woven or knitted, although the benefits of the invention are more readily obtained with knitted fabrics, and especially with knitted fabric having a cover factor in the range of 0.80-1.25, depending on the yarn type. Woven fabrics subjected to the process of the invention should also preferably be of a tight rather than a slack woven construction.

Various types of stabilising agent can be employed. In general, they can be divided into two classes. The first class includes various compounds that are normally regarded as reducing agents for keratin, namely, alkali metal, alkaline earth metal, ammonium and amine sulphites and bisulphites. The second class comprises curable resins which impart to keratinous fibres a resistance to shrinking when the corresponding fabrics are washed, particularly in a domestic washing machine.Examples of such resins are polyacrylates, polyethylene imines, condensation products of polyamides with epichlorhydrin, for example, the product sold under the trade name Hercosett 125, and organothiosulphates having the general formula

where R1,23, can be

where M+ is sodium, potassium, ammonium or an amine ion, and n is an integer from 5 to 25 preferably about 1 3. An example of such a material is the material obtainable under the trade name Lankrolan SHR3. Good results have also been obtained using silicones and the condensation product of acetone oxime and a product available under the trade name Desmodur E.14.However, the resins which have been found to give the best results in the process of the invention are polyisocyanates and especially the bisulpliite addition products thereof of the general formula given hereinbefore in respect of organothiosulphates, in which R, 2 3 are each

particularly those which are available under the trade name Synthappret BAP.

Depending upon the stability of the stabilizing agents in the presence of water, the agents can be applied either in the form of aqueous preparations or as solutions in an organic solvent.

Preferably there is used a mixture of stabilising agents, one from each class since then shorter embossing times can be achieved.

The stabilising agent must be converted into a print paste for use in the present process. This can be achieved by mixing the stabilising agent with a thickening agent or thickening means. In general conventional methods of making the paste can be used, namely mixing the required ingredients together using a high speed mixer. The precise mixing method will depend to a large extent upon the chemical nature of the stabilising agent. For example, when the stabilising agent is a reducing agent or certain of the curable resins, one procedure which can be adopted is to emulsify the agent in the presence of water and a hydrocarbon liquid, for example, white spirit, in the presence of an emulsifying agent, for example, the product sold under the trade name Matexil PNPR.

The thickening agents employed can be of natural or synthetic origin. As examples of thickening agents there can be mentioned polyacrylic acid, polyvinyl alcohol and the materials available under the following trade names: Name Composition Manutex Sodium alginate Acraconc Synthetic thickening agent based on polycarboxylic acids Natrosel Hydroxy ethyl cellulose Indalca Plant seed gum ether Gauranate Guar gum derivative Polyprint Plant seed gum ether Prisulon Plant seed gum ether Solvitose Starch ether It is important to avoid using components in the print paste which react to any significant extent with one another because this can lead to undesirable characteristics in the embossed fabric.In general the preferred resins, namely, the polyisocyanates, tend to react with some materials, for example, those containing reactive hydrogen atoms, used to thicken a liquid composition containing the stabilising agent. It has been found however that excellent print pastes can be obtained using alginates as a thickening agent, for example, those available under the trade name Manutex RSB.

Certain pastes especially those containing a resin tend to be acidic. In such cases the pH of the paste is preferably increased to about 7.5 by the addition of a weakly basic substance, for example, sodium sulphite or sodium bicarbonate. The former has an advantage in that when the treated fabric is embossed by heating under pressure the presence of the sulphite enables shorter pressing times to be employed. The paste can also desirably include a softening agent, for example, products available under the trade names Persoftal SWA and Alcamine CA New. Softeners, however, can also be applied as an afterwash.

The quality of the embossing and the characteristics of the embossed fabric can in certain cases be improved considerably if, prior to the printing step, the fabric or the yarns or fibres comprising the fabric are treated with chlorine. A convenient procedure is to treat the pre-made garment with a chlorinating agent, for example, sodium hypochlorite or preferably an alkali metal salt of dichlorocyanuric acid which is available under the trade names Basolan or Ficlor-Clearon in which case the chlorinated material may require treatment with a dilute solution of a base or an alkaline metal suiphite to remove any excess chlorine.

Knitted fabrics prior to printing should also be subjected to certain routine treatments associated with wet finishing routines. For example, fabrics knitted from wollen spun yarns should be scoured and milled whilst fabrics knitted from worsted spun yarns should be subjected to an anti-cockling treatment and then scoured. Various methods can be used for the anti-cockling step, for example, heating the material in a bath containing a reducing agent, for example, sodium bisulphite, and a surface active agent, for example, the product sold under the trade name Tergitol speedwet. Scouring can be carried out conveniently by heating the material in a bath containing a surface active agent, for example, the product sold under the trade name Lissapol N. Printing is carried out in a conventional way using a suitable blank screen and a squeegee.

The embossing process can be carried out on conventional flat head presses, for example, a Hoffmann Hosiery press. The embossing conditions will depend to a large extent on the type of press employed. However, pressures of about 80 Ibs. per sq. in. and temperatures in the region of 100/1 050C have generally been found satisfactory. The process is carried out preferably in the presence of steam. Furthermore, it is important to heat the press and the die to be used for embossing to its working temperature prior to the introduction of the material to be embossed. The material can be wet or dry, however it is generally more convenient to emboss a dry fabric because it is easier to handle and requires a shorter pressing time.The pressing time depends upon conditions and the nature of the ingredients used in the print paste but they generally vary from 0.5 to 4 minutes. In general, shorter pressing times of about 0.5 minutes can be employed if a reducing agent, for example, sodium suiphite, is present in the printing paste and the printed fabric is dried, prior to embossing.

In order to ensure a satisfactory depth of embossing a layer of heat resistant resilient material, e.g. a silicone rubber, is preferably positioned between the area of fabric to be embossed and its support.

The procedure to be adopted after completion of the embossing process can vary depending upon whether a curable resin has been used as the stabilising agent. When this is the case some curing will usually take place whilst the fabric is heated in the press. In order to ensure completion of the process the embossed fabric is placed in an oven and heated to a temperature sufficient to cure the resin (usually 11 0-1 20CC) for a period of 8-12 minutes. This heating step is not required when a reducing agent is used in the absence of a resin as the stabilising agent. After embossing, the material is generally somewhat stiff and possesses a poor handle due to the presence of water soluble components of the print paste. The next step consists therefore in subjecting the embossed fabric to a wash, a final rinse and then drying the material.The resultant product has excellent softness and the pattern possesses high definition which is resistant to further washing.

This invention is illustrated by the following Examples: Example I The following process was applied to a fabric having a cover factor of 1.1 5 (in-l w.c.-1/2) obtained by knitting 2 24's w.c. worsted yarns made of botany wool.

Pre-treatments (i) Anti-cockling The fabric was subjected to a standard anti-cockling treatment by heating in a bath containing a boiling solution containing 3% o.w.w. sodium bisulphite and 1 91- of a surface active agent available under the trade name Tergitol Speedwet. The fabric was agitated in the bath for 3 minutes after which it was allowed to soak for a further 1 5 minutes.

(ii) Scouring The fabric was scoured by transference to a bath heated to 400C containing 1 gel~' of a surface active agent available under the trade name Lissapol N and 2.2 91- of anhydrous sodium sulphate. 5% o.w.w. of sodium bicarbonate was also added to neutralise the fabric. The latter was then agitated in the bath for 10 minutes and then removed and rinsed thoroughly.

(iii) Chlorination The fabric was agitated for 10 minutes at 200C in water adjusted to pH 6.0 with acetic acid, after which a solution containing 4.0% o.w.w. of Ficlor Clearon was added. After 20 minutes the bath was adjusted to pH 5.0 with dilute acetic acid and agitation continued for 10 minutes, after which the pH was adjusted to 4.0 and treatment continued until the bath became exhausted. 3.09/0 o.w.w. sodium bisulphite was then added and the treatment continued for 10 minutes. The fabric was then neutralised in a fresh bath at 400C and pH 7.0 using sodium bicarbonate for 1 5 minutes, after which it was rinsed thoroughly and tumble dried.

All these pre-treatments were carried out at a liquor to goods ratio of 30 to 1.

Print paste The paste was prepared by agitating vigorously together the following ingredients in the proportions stated:- Manutex RSB 1.00% Synthappret BAP 1.25 Sodium suiphite (hydrated) 0.25 Persoftal SWA 1.00 Water 96.50 100.00% The pH of the paste was adjusted to 7.5 by the addition of the sulphite to ensure minimal curing of the resin during drying.

Application of print The paste was applied to the fabric in the area to be embossed, using a suitable blank screen and weighted double bladed squeegee. The fabric was mounted on a former so as to impose a 10% area stretch. Sufficient strokes were employed to obtain adequate, but not excessive, paste penetration. The pick-up was estimated to be in the region of 200%. The sample was then removed from the former and flat dried at a temperature of 45-550C.

Embossing After the fabric had been dried, a piece of silicone rubber, slightly larger than the printed area, was inserted between the printed panel and the former. This was essential in order to obtain a suitable depth of emboss in the relief areas of the die. The mounted sample was then transferred to a preheated hosiery steam press and embossing carried out at a temperature of about 100/1 050C for a period of 30 seconds at an air line pressure of 80 Ibs.in-2.

The material was heated in an oven for 10 minutes at 11 00C to complete the curing of the resin after which the fabric was washed off at 400C for 10 minutes and then rinsed in a fresh bath, at pH 5.0 and 200 C, for 10 minutes. The fabric was finally hydro-extracted, tumble dried and subjected to the following washing test: A quantity of embossed fabric weighing 200 gms was placed in a laboratory washing machine, containing 1 5 í water at 400 C, sold under the trade mark Cubex. 800 gms of makeweight material was then added together with 120 gms of disodium phosphate and 67.5 gms of monosodium orthophosphate. The material under test was then washed for one hour after which it was removed, hydro extracted and flat dried.Notwithstanding the severity of this treatment, the embossed pattern was found to have retained excellent definition.

Example II The following process was applied to a lambswool pullover made from 2/15's w.c. lambswool woollen yarn knitted to c.f. 0.95 (in-' w.c.-1/2).

Pre-treatment The garment was first scoured in the manner described in Example 1 except that a surface active agent sold under the trade name Lissapol NX was used. After rinsing, the garment was milled in a rotary washing machine at 400C in an aqueous solution containing 0.25 gI1 of a milling agent available under the trade name Lev'nite SH 1 3 until the desired finish was obtained. The garment was thoroughly rinsed again, after which it was chlorinated according to the method described in Example 1, except that 3.2% of the chlorinating agent was employed.

The print paste was then prepared by mixing the following ingredients in the proportions stated.

The amount of sodium sulphite added was sufficient to adjust the pH of the paste to 7.5.

Manutex RSB 1.0% Synthappret BAP 2.5 Sodium sulphite (hydrated) 0.7 Water 95.8 100.0% The garment was then mounted on a former shaped to the design and style the garment. The former was sufficiently rigid to hold the garment in a stretched position and yet flexible enough for ease of mounting. The area of the garment was increased by stretching by about 10% and the welt of the garment was secured by a length of tape available under the trade name Velcro.

The front panel of the garment was then printed as in Example 1 using a printing screen and a weighted double bladed squeegee. In order to avoid setting of the rib in the area of the welt of the garment the screen was aligned so as to prevent application of paste to the welt area. The garment was then removed from the former and flat dried for 30 minutes at 450C. prior to embossing. The garment was then transferred to a second former which, while possessing properties similar to the one used in the printing operation, was also resistant to softening and distortion by subsequent steaming. A piece of silicone rubber the size of the printed panel of the garment was attached. The garment was positioned on the press and the die aligned along the top of the welt. Prior to embossing care was taken to warm the press to prevent condensation of steam. The garment was heated in the presence of steam for 0.5 minutes at an air line pressure of 80 Ibs. per sq.in. and steam pressure of 50 Ibs. per sq.in. The garment was then removed from the former, cured at 11 00C for 10 minutes, and washed off as described in Example 1, with application of 1.5% (oww) of a softening agent available under the trade name Alcamine CA New, applied from the final rinse. It was then hydro-extracted and tumble dried.

At the end of the process the garment was found to have very soft handle and the pattern retained a high quality of definition when the garment was subjected to the washing test described in Example 1.

Claims

1. A process for embossing a fabric containing keratinous fibres, wherein a predetermined area of fabric is printed with a composition comprising a stabilizing agent for the keratinous fibres and a thickening agent, the treated material is dried and embossed and the embossed material is then washed to remove the thickening agent.

2. A process according to claim 1, wherein the keratinous fibres are sheeps wool.

3. A process according to claim 1 or claim 2, wherein the fabric is a knitted fabric.

4. A process according to claim 3, wherein the fabric is a knitted fabric having a cover factor in the range of 0.80 to 1.25.

5. A process according to any one of claims 1 to 4, wherein the stabilizing agent is a compound that is a reducing agent for keratin.

6. A process as claimed in claim 5, wherein the stabilizing agent is an alkali metal, alkaline earth metal, ammonium or amine suiphite or bisulphite.

7. A process as claimed in any one of claims 1 to 4, wherein the stabilizing agent is a curable resin which imparts shrink resistance to keratinous fibres.

8. A process according to claim 7, wherein the curable resin is an organothiosulphate of the general formula

where RX,2,3, can be

where M+ is sodium, potassium, ammonium or an amine ion, and n is an integer from 5 to 25 preferably about 13.

9. A process according to claim 7, wherein the curable resin is a polyisocyanate bisuiphite addition product of the general formula

wherein R1,2,3, are each

and M+ is sodium, potassium, ammonium or an amine ion, and n is an integer from 5 to 25 preferably about 13.

10. A process according to any one of claims 1 to 9, wherein the stabilizing agent comprises a combination of a reducing agent for keratinous fibres and a curable resin imparting shrink resistance.

11. A process according to any one of claims 1 to 10, wherein the thickening agent is an alginate.

12. A process according to claim 1, conducted substantially as described in either of the Examples.