GB2112422A

GB2112422A - Transfer printing of natural silk

Info

Publication number: GB2112422A
Application number: GB08232548A
Authority: GB
Inventors: Sen Pao Chuang; Roger Montavon
Original assignee: CHINA DYEING WORKS Ltd; Ciba Geigy AG
Current assignee: CHINA DYEING WORKS Ltd; Novartis AG
Priority date: 1981-11-17
Filing date: 1982-11-15
Publication date: 1983-07-20
Also published as: JPS62250288A; IT1148667B; FR2516562B1; IT8249486A0; HK85885A; GB2112422B; FR2516562A1; JPS5887380A

Abstract

A method of transfer printing silk which contains 10 to 30% of a swelling agent, comprising the use of transfer papers printed with patterns containing readily volatile dyes, at 160 DEG to 210 DEG C. Patterns of virtually equal strength are obtained on both sides of the so printed silk. The process is characterized by the use of a dye of formula: <IMAGE> in which the alkyl group has 1-4 C atoms, <IMAGE> in which R is H or phenyl and X is a non-ionic substituent such that the dyestuff has a molecular weight of 200-300 and <IMAGE> in which X is H, OH, or NH-R1 where R1 is a lower alkyl group, Y is identical with R1 when X is H, or H when X is NH-R1 or a chlorine or bromine atom, a methoxy or trifluoroethoxy group when X is OH and Z is H when X is H or OH and NH-R1 when X is NH-R1.

Description

SPECIFICATION Transfer printing of natural silk The present invention refers to a process for printing natural silk according to the well known transfer printing method which is described for instance in French patents 1 223 330 and 1585119.

It is known that silk cannot be transfer printed because it has practically no affinity and no solubilizing power for the disperse dyes used in transfer printing. To palliate this drawback the inventors of Japanese patent publication No. 53106883 use fabrics of grafted silk, namely fabrics whose silk threads have been grafted polymerized with styrene or another vinyl monomer. Graft polymerisation is however a pretreatment of the silk threads, which involves a chemical reaction and the presence of a chemical catalyst. It is therefore rather complex.

Another way of rendering silk transfer printable is its acylation as described in the Chinese publication Hsin Hsien Wei (Series 22, issue 12 of 1 980 p.33-37). This is also a rather complicated and expensive procedure.

In the Japanese patent publication No. 53- 78386 a simpler pretreatment is proposed. The silk fabric is impregnated with 10100% of a polyhydric alcohol having a boiling point higher than 1 400 C. The so treated silk may be transfer printed with transfer papers bearing sublimable basic dyes. It is indicated in this publication that disperse dyes may be used with the basic dyes.

The main disadvantage of the process claimed and described in this patent publication is the lack of penetration of the dyes used within the silk fabric which shows quite different shades on its back side than on the front.side. The fastness of the prints obtained according to this procedure is also rather weak.

It is one object of the present invention to provide a simple process for transfer printing silk.

Another object of the present invention is to provide a process for printing silk fabrics so that the back side does not differ too much in hue from the front side.

It is a further object of the invention to provide a process in which the transfer printing method may effectively be applied to silk fabric without having to carry out a chemical reaction either with the silk thread or with the dyestuffs.

Another object of the invention is to provide an economical process for printing silk without depriving it from its original handle, lustre or other physical properties.

Further objects will become apparent from the following disclosure and examples.

In the present process silk fabrics the threads of which contain 1030% of a swelling agent are heated at a temperature between 1600-- 21 00C for 20 to 60 seconds in contact with a transfer sheet printed with at least one of the dyestuffs of the following formulae::

alkylC N alkyl wherein alkyl is an alkyl group having one to.four carbon atoms, particularly a methyl, ethyl and isopropyl group

wherein R is H or a phenyl group and X a non ionic substituent such that the dyestuff has a molecular weight between 200 and 300, and

wherein X is H, OH or NH-R1, R, being a lower alkyl group such as methyl, ethyl or isopropyl group, Y is identical with R1 when X is H, or H when X is NH-R1 or a chlorine atom a bromine atom, a methoxy or a trifluoro ethoxy group when X is OH and Z is H when X is of H or OH, and NH-R1 when X is NH-R1.

As representative examples of dyestuffs of the formula II there may be mentioned the 4-tolylazo-3-methyl-5-pyrazolone, the 1 -phenyl-3methyl-4-phenylazo-5-pyrazolone and the 1phenyl-3-methyl-4-(m-tolylazo)-5-pyrazolone. As dyestuffs of the formula Ill may be mentioned particularly the 1 -amino-2-methylanthraquinone, the 1-amino-2-trifluoroethoxy-4-hydroxyantrhra- quinone, the 1-amino-2-chloro- or bromo-4hydroxythraquinone, the 1 ,4-diisopropylaminoanthraquinone. All these dyestuffs are known and can be made by knowm methods.

In the present invention the silk has been pretreated with a chemical agent having swelling action and having a boiling point preferably not lower than 1 500C, for example, a polyhydric alcohol or a derivative thereof, or an aqueous solution or an aqueous dispersion thereof. For instance, a silk article is immersed in an aqueous solution or dispersion containing at least 10 weight percent, preferably 1 5 to 30 weight percent of the swelling agent, and after squeezing it to a wet pick up of 50 to 100%, the article may be subjected to intermediate drying. The temperature of the intermediate drying depends on the particular swelling agent used but is generally below 1 200C. As the method of applying a swelling agent, spraying or coating method can also be used.

As examples of the swelling agents for silk to be used in the present invention can be mentioned the following polyhydric alcohols and derivatives thereof: alkylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, butane diol, pentane diol, hexylene glycol, or octylene glycol; alkylene glycol mono- and diethers such as ethylene glycol monomethylether, ethylene, glycol monoethylether, diethylene glycol nonobutylether, diethylene glycol dimethylether, diethylene glycol diethylether, dipropylene glycol monomethylether, alkylene glycol mono- and diesters such as ethylene glycol monoacetate, ethylene glycol diacetate, polyalkylene glycols such as polyethylene glycol of average molecular weight of 200 to 4000 polypropylene glycol of average molecular weight of 400 to 5000 or polyethylene glycol/polypropylene glycol block copolymer of average molecular weight of 400 to 5000; 1-butoxyethoxy propanol, polyhydric alcohols such as glycerin, trimethylol propane, addition products of polyhydric alcohols and alkylene oxides; addition products of polyhydric alcohols and lactones.The most preferred ones among them are polyalkylene glycol such as polyethylene glycol (average molecular weight 250 to 1000), polypropylene glycol (average molecular weight 250 to 1000), polyethylene glycol boric acid esters.

According to the present invention, the pretreated article is placed below or superposed with a transfer sheet having been previously printed with a printing ink containing the said sublimable disperse dyes, and the superposed assembly is heated under pressure to sublime the sublimable dye into the textile article. Where the pretreatment agent is a boiling point agent that cannot be removed by distillation, it is desirable that the pretreatment agent is removed by waterwashing after transfer printing to fix and stabilize the dye on the silk.

As a transfer sheet it is known to use any sheet having a printed pattern printed with an ink containing a sublimeable disperse dye as indicated and binder (e.g. methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, polyvinylpyrrolidone, gelatine, polyvinylalcohol, polyacrylamide, acrylic ester or methacrylic ester) on a temporary support such as paper or film. Since these transfer sheets and preparation thereof are well known in the art no further explanation thereabout will be necessary.

The transfer itself is carried out at 1 60- 21 00C preferably 180-1 900C during 20 to 60 preferably 30 to 50 seconds. A yellowing of the silk may be prevented by transferring at as low a temperature as possible within the said limits or by using a transfer paper which has been over lacquered with an optical brightening agent subliming at 1600--2100C. Such agents are mentioned in French patent 1 574 528 which describes also the preparation of transfer sheets therefrom.

After transfer the transfer sheet is removed from the silk which may then be rinsed in order to remove the swelling agent and dried.

The so printed silk may also be posttreated as usual to confer to the fabric the resilience, gloss, handle and so on which is commonly imparted to silk fabrics in order to enhance their commercial value. The fabrics so printed show the same or practically the same shades on both sides.

According to the method of the present invention it is possible to dye silk articles. It is also possible to dye an article composed of silk and synthetic or semisynthetic fibers in an even and same color in both the silk part and synthetic or semisynthetic part. Moreover, one of the consequences of using the method of the present invention is that good results are also obtained even when the method is applied to a fabric such as lawn or voile which has been generally unable to be printed because of loose texture.

The printed articles prepared by methods according to the present invention represent a sharp-edged, delicate pattern and are satisfactory enough to meet the demand of consumers.

The present invention will be explained in further detail by means of the following Examples wherein the parts and percentages are by weight.

Example: A silk fabric was immersed in a 30% aqueous solution of polyethylene glycol (mol. wt. 300), was squeezed to a wet pick up of 100% and dried at 700C for 10 minutes. Separately, a sheet of paper for gravure printing was printed with a printing ink prepared by dispersing 10 parts of 1 amino-2-chloroanthraquinone and 6 parts of ethyl cellulose in a mixed solvent of isopropanol/ethanol (1/1) using a gravure printing machine and was dried to prepare a transfer printing sheet.

The foregoing silk treated with polyethylene glycol (molecular weight 300) was superposed with the transfer sheet and was pressed at 1 kg/cm2 under heating at 2000C for 30 seconds in a flat plate press. The thus-printed silk was immersed in water, squeezed to a wet pick-up of 70% and dried at 1000C for 4 minutes.

The resulting fabric shows a bluish red design having the same shade on both sides.

By using the 1 ,4-diisopropylaminoanthraquinone in the foregoing example a blue desiqn is obtained.

Multicolor designs are obtained by this procedure by using as yellow dyestuff, 1 -phenyl- 4-phenylazo-3-methyl-5-pyrazolone, as red dyestuff, 1 -amino-2-trifluoroethoxy-4- hydroxyanthraquinone and blue dyestuff, 1 4- diisopropylaminoanthraquinone.

Claims

1. A method of transfer printing silk which contains 10 to 30% of a swelling agent, wherein the silk is heated at a temperature between 1 600C and 2100C for 20 to 60 seconds in contact with a transfer sheet printed with at least one of the dyestuffs of the following formulae:

alkyl Xb (I) wherein alkyl is an alkyl group having one to four carbon atoms,

wherein R i H or a phenyl group and X a non ionic substituent such that the dyestuff has a molecular weight between 200 and 300, and

wherein X is H, OH or NH-R1, R1 being a lower alkyl group, Y is identical with R1 when Xis H, or H when X is NH-R1 or a chlorine atom, a bromine atom, a methoxy or trifluoroethoxy group when X is OH and Z is H when X is H or OH, and NH-R1 when X

2. A method as claimed in claim 1 in which alkyl in the dyestuff of formula I is methyl, ethyl or isopropyl.

3. A method as claimed in claim 1 in which R in the dyestuff of formula Ill is a methyl, ethyl or isopropyl group.

4. A method as claimed in any preceding claim, wherein the silk is a woven fabric or a knit fabric composed of 100% silk or a blend of silk with synthetic fibers.

5. A method as claimed in any preceding claim, wherein the swelling agent is a polyhydric alcohol or a derivative thereof.

6. A method as claimed in claim 5 in which the swelling agent is a polyethylene or polypropylene glycol having a molecular weight of 300-500.

7. A method as claimed in any preceding claim, wherein the silk is rinsed after having been separated from the transfer sheet.

8. A method as claimed in any preceding claim, wherein the dyestuff of the formula

is used as yellow dyestuff.

9. A method as claimed in any preceding claim, wherein 1-amino-2-chloro- or bromo-4-hydroxy- anthraquinone is used as red dyestuff.

10. A method as claimed in any preceding claim, wherein 1 ,4-diisopropylaminoanthraquinone is used as blue dyestuff.

11. A method as claimed in claim 1 substantially as hereinbefore described with reference to the foregoing Example.

12. A printed silk obtained according to one of claims 1 to 11.