WO1999010593A1

WO1999010593A1 - Method of printing on textiles

Info

Publication number: WO1999010593A1
Application number: PCT/GB1998/002580
Authority: WO
Inventors: Mark Richard Shepherd; Jill Woods; John Phillip Tatum; Stephen Temple
Original assignee: Xaar Technology Limited
Priority date: 1997-08-27
Filing date: 1998-08-27
Publication date: 1999-03-04
Also published as: GB9718112D0; AU8873898A

Abstract

A method of printing on textiles by ink jet printing using a dispersion ink comprising a dispersion of colorant in a non-aqueous liquid diluent, said dispersion further including a dispersant comprising a film-forming component.

Description

METHOD OF PRINTING ON TEXTILES

This invention relates to printing on textiles and in particular to printing on textiles using an ink jet printer.

The use of ink jet printers to print on textiles is known. An advantage of ink jet printing over other methods of printing on textiles is the ease with which a design or pattern can be changed; every print can be different.

Hitherto, dye-based inks using sublimable dyes have been employed. However, such inks have the disadvantage of requiring the use of heat to fix the print and develop the colour.

We have now developed a method of obtaining a wash- fast print on textiles by ink jet printing with a dispersion ink. In one embodiment the print is also heat stable up to temperatures of at least 200°C.

According to the present invention there is provided a method of printing on textiles by ink jet printing using a dispersion ink comprising a dispersion of colorant in a non-aqueous liquid diluent, said dispersion further including a dispersant comprising a film-forming component. With suitable choice of components the ink can be printed under ambient conditions to give print of excellent definition and good fastness to water and normal washing procedures and no further processing is required. Drying of the print is believed to be primarily through rapid separation of the disperse phase from the diluent on contact with the textile, with the colorant, e.g. pigment, becoming keyed to the surface of the textile and the diluent being absorbed away.

The ink should have all the usual properties required of an ink jet printer ink including stability of the dispersion on storage and in the print head of the printer, a low viscosity generally not exceeding 30 MPas, preferably no greater than 20 MPas, more preferably no greater than 15 MPas, as measured by a Bohlin CS rheometer with a CP40 cone and plate geometry at a shear rate of at least 10 sec^"1, a surface tension in the range 27 to 72 dynes/cm at

25°C, and sufficiently low volatility to avoid blockage in a printhead channel or nozzle due to evaporation while the nozzle is inactive.

Viscosity modifiers may with advantage be incorporated in the ink composition used in accordance with the present invention. Examples, which may enhance or reduce the viscosity, include higher esters of polycarboxylic acids, suitably C₆ to C₁₀ alkyl esters of aliphatic or aromatic dicarboxylic acids. Such materials include the C₆ (or C₈, in the case of aromatic acids) to C₁₂ dicarboxylic mono and diesters many of which are sold commercially as plasticisers for plastics materials. Examples include dioctyladipate, dioctylphthalate, dioctylsebacate, the mono isobutyrate of 2,2,4 -trimethylpentan-1 , 3-diol or texanol and the di- isobutyrate of 2,2,4- trimethylpentan-1, 3-diol sold as KODAFLEX TXIB .

On the other hand, although the drying of the ink does not rely primarily on evaporation, if the volatility of the diluent is too low, rapid drying of the print may be inhibited.

The components of the ink will now be discussed in greater detail .

The diluent, which may be a single component or a single phase mixture, is required to be non-aqueous, which is to say that it must contain substantially no water other than that normally found as a normal contaminant in commercially available forms of the selected component or components of the diluent e.g. due to absorption of moisture from the air. It is therefore essentially organic in nature. In general, the water content of the diluent should not exceed 5%, and preferably 1% by weight. With higher amounts of water, the stability of the ink would be prejudiced. Examples of classes of compounds from which the component or components of the diluent may be selected are hydrocarbons, and, more especially, polar compounds such as substituted e.g. halogenated hydrocarbons, alcohols, ketones and, particularly, esters and ethers.

Examples of ethers that may be used are found amongst alkyl, suitably Cj to C₄ alkyl , preferably monoalkyl such ethers of alkylene and polyalkylene glycols, especially monomethyl ethers of polypropylene glycols e.g. di- or tri- propylene glycol .

Examples of esters that may be used are mono or dialkyl esters, suitably dialkyl esters of dicarboxylic acids, preferably di-C₃ to C₅ alkyl such esters such as the dibutyl esters of adipic, succinic and glutaric acids. Examples of mono alkyl esters include the butyl or 2-ethylhexyl esters of lactic acid.

Mixtures of the above mentioned ethers, mixtures of the above-mentioned esters and mixtures of one or more of the above-mentioned ethers with one or more of the above- mentioned esters may also be used. Where one or more compounds selected from these esters and ethers is a relatively high boiling material, the or each such material may be used in admixture with one or more lower boiling materials which are fully miscible therewith in order, for example, to increase the drying rate of the ink. However, it is understood that the amount of such lower boiling material present should not be such as to cause evaporation in the channels or nozzle of the printhead leading to blockage when the nozzle is inactive. To this end, it is preferred that the diluent composition is such that not more than 50% thereof is volatilised below 150°C.

Examples of such lower boiling materials are the lower mono- or di- alkyl, e.g. methyl or ethyl, ethers of low molecular weight glycols, e.g propylene glycol monomethyl ether; and the lower mono- or di- alkyl, e.g. methyl or ethyl, esters of low molecular weight carboxylic acids; e.g. ethyl acetate, ethyl lactate, dimethyl succinate, dimethyl adipate, dimethyl glutamate and the like.

Ink compositions based on diester diluents tend to be more stable at high ambient humidity levels than those based on ether diluents.

Any suitable colorant may be used provided it is insoluble in the diluent and may be dispersed in it to form a stable dispersion. Preferred colorants are pigments found amongst those characterised as pigment dyes in The Colour Index. Preferably the pigment will be of a primary subtractive hue. The pigment should be lightfast, and thermally stable even with repeated warming. Examples are carbon blacks, pigment blacks and colorants of the following chemical types : azo condensation colorants such as Chromophtal Yellow 3G (CI designation PY 93), Chromophtal Yellow 8GN (PY 128) , Chromophtal Scarlet R (PR 166) ;

BON acrylamide colorants such as Novoperm Red F3RK70 (PR 170) , Permanent Rubine F6B (PR 184) ; disazo colorants such as Novoperm Yellow HR 70 (PY 83) Permanent Yellow DGR (PY 13) , Permanent Yellow GRL 80 (PY127) , Permanent Yellow GRX 80 (PY 176) , Sandorin Yellow 4G (PY 155), Sandorin 6 GL (PY 173); monoazo colorants such as Novoperm Yellow FGL (PY 97) ; phthalocyanine colorants such as Heliogen Blue 7084 (PB 15.3), Heliogen Blue 7106 (PB 15.4), Ergalite Blue GLVO (PB 15.4), Astral Blue FGX (PB 15.4); quinacridone colorants such as Cinquasia Magenta RT 235-D (PR 202) , Cinquasia Violet RRT 791-D (PV 19), Hostaperm Red E2B70 (PV 19) , Hostaperm E5 B02 (PV 19) , Sunfast Violet 19 228 0022 (PV 19) , Sunfast Violet 19 228 0594 (PV 19) and substituted quinacridone colorants such as Hostaperm Pink E (PR 122) for example dimethylquinacridone colorants such as Sunfast Magenta 122 228 0641 (PR 122) and dichloroquinacridone colorants such as Sunfast Magenta 202 (PR 202) ; quinophthalone colorants such as Paliotol Yellow DO960 ( PY 138 ) ; and tetrachloroisoindolinone colorants such as Iragazin

Yellow 2RLT (PY 110) .

All of these pigments were found to be alkali, and usually alkali bleach, resistant under the following test conditions: 0.2g of the pigment was mixed with 2. Og or aqueous alkali (4% NaOH) or with aqueous alkali bleach (4% NaOH; 7% NaOCl) and the mixture was heated at 70 °C for 30 minutes. The test was carried out on a ceramic spotting dish and qualitative visual assessment was made.

The amount of colorant employed will depend on the choice of colorant but will normally be in the range of 2 to 20, and preferably 4 to 15, % by weight of the ink.

The use of a film-forming dispersant endows the print obtained from the ink with good wash fastness. By film- forming is meant that a solution or dispersion of the dispersant in a solvent or diluent will form a coherent film on a substrate on removal of the solvent or diluent, e.g. by evaporation. The film-forming dispersant should be chosen with regard to the nature of the diluent and the choice of colorant to provide a stable dispersion of the colorant in the diluent. By a stable dispersion is meant that no separation is detectable by the naked eye in a sample of the ink after standing for 30 days at 25°C. Preferably, the stability is such that no such separation is detected after 90 days at 25°C and more preferably 180 days at 25 °C.

A mixture of film-forming dispersants may be used if desired and also the film forming dispersant or dispersants may be used in admixture with one or more non-film- forming dispersants and/or dispersant synergists provided that said non-film-forming materials are not present in an amount sufficiently large to adversely affect wash fastness. In general, the film-forming dispersants will be selected from film- forming polymeric materials such as urethane polymers, acrylate polymers, urethane acrylates, polyvinyl alcohol, polyvinyl esters, and polyesters.

In accordance with one preferred embodiment of the invention, at least the film- forming dispersant is water- immiscible since this is believed to increase the rate of drying the print and aid wash fastness. A preferred class of water- immiscible film-forming dispersants, particularly for use with diluents containing ether and/or ester, are urethane polymer-based such as those sold under the trade mark EFKA, e.g. EFKA 4747.

The amount of dispersant required will depend upon the nature of the colorant and the choice of dispersant. In general, it should be employed in at least the minimum amount required to achieve a good mill base when milled with the chosen colorant. It is considered that a good mill base is obtained when there is substantially no detectable build up of undispersed colorant during milling. An excess of this minimum amount may be used, if desired, provided it does not cause destabilisation of the ink. In general, the optimum amount of dispersant is found to be that which gives the minimum viscosity of ink. Typically, the dispersant is employed in an amount of at least 20%, generally 20 to 150%, and more usually 25 to 100% by weight, based on the weight of colorant.

Other components conventionally used for ink jet printer inks, e.g. antioxidants , may also be included in the ink compositions employed in the present invention, if required.

The ink may be made by forming a stable dispersion comprising colorant, dispersant and sufficient of the diluent to form a workable paste, and then adding the remainder of the diluent. The first step may include milling and it is preferred to obtain a particle size for the disperse phase of 1 μm or less. Preferably, the majority of the particles are not more than 0.5μm and none are more than 5μm. By particle size, we mean equivalent spherical diameter as measured by techniques such as photon correlation spectroscopy . Inks having the composition defined above may be formulated for use in any of the available kinds of continuous and drop-on-demand printers. In the former kind, for example, ink droplets which are produced continuously may be passed through a charging area where individual droplets receive an electrical charge in response to a signal and are directed towards a substrate to be printed. The droplets then pass through an electrical field causing them to be deflected by an amount which is dependent on the intensity of the charge and the field. Droplets not required to form print on the substrate may be directed to a by-pass gutter. For inks of the present invention to be suitable for use in such printers, they are preferably conductive and it may therefore be necessary to include a suitable conducting additive. The latter printers may be of the kind using an electrostatically accelerated ink jet or droplet sequences ejected by pressure impulse actuation, e.g. when each droplet is individually ejected from a nozzle by means of pressure pulses induced e.g. by means of a piezoelectric actuator acting on the ink in the channel supplying the nozzle .

Textiles which may be printed in accordance with the invention may be woven or non-woven and may also include, for example, knitted fabrics and lace. The invention is considered to be particularly applicable, however, to clothing and furnishing fabrics such as for curtains and upholstery. There seems to be no limit to the nature of the fibres and filaments from which the fabrics may be made and excellent results have been obtained on cotton mixes, polyester/cotton, polyester and polyester/rayon mixes.

The invention is now illustrated by the following Examples in which all parts and percentages are by weight unless indicated otherwise.

EXAMPLE 1 Black formulation A: 11% Regal 250R

6.8% EFKA 4747

82.2% TPM

EXAMPLE 2

Black formulation B: 11% Regal 250R 6.8% EFKA 4747 82.2% COASOL

EXAMPLE 3

Yellow formulation: 5% Paliotol Yellow D 1155 2.2% EFKA 4747 92.8% TPM

EXAMPLE 4

Magenta formulation: 5% Hostaperm Red E5B02 3.4% EFKA 4747 91.6% TPM EXAMPLE 5

Cyan formulation: 5% Heliogen Blue S7084

5% Solsperse 12000 1-7% EFKA 4747 92-8% TPM In the formulations of Examples 1 to 5 inclusive, the amount shown of EFKA 4747 is the actual amount of that product. It is used let down in a portion of the TPM or COASOL shown.

Inks in accordance with the formulation of Examples 1 to 5 inclusive were successfully printed under ambient conditions using a piezo drop-on-demand printer onto samples of linen (100% cotton) , 100% polyester, 50/50 polyester/rayon and 50/50 polyester/cotton. In all cases well defined print was obtained having a good colour density and with no smudging or blurring.

In a wash test, it was found that the print remained fast and of undiminished colour after washing in a conventional domestic washing machine with a conventional domestic detergent at 40 °C.

In a further test, cotton, polyester and cotton/polyester samples printed with each of the coloured ink formulations was subjected to heat treatment at 200°C and then washed at 40°C with a conventional domestic detergent. In all cases, the print was found to be unaffected by the treatment . This is of significance in the manufacture of garments such as brassieres which involve a step of moulding under heat.

All the above formulations had a viscosity of less than 30 MPas and surface tension in the range 27 to 72 dynes/cm.

EXAMPLE 6

Black formulation: 11% Elftex 325 19.4% EFKA 4747 69.6% COASOL

EXAMPLE 7

Yellow formulation: 5% Paliotol Yellow D 0960 5% EFKA 4747 28% UNIFLEX DOS 62% COASOL

EXAMPLE 8

Cyan formulation: 5% Irgalite Blue GLVO 5% EFKA 4747 0.5% Solsperse 5000 33.3% UNIFLEX DOS 56.2% COASOL EXAMPLE 9

Magenta formulation: 7% Hostaperm Red E2B70

7% EFKA 4747 10-15% UNIFLEX DOS 76-71% COASOL

EXAMPLE 10

Magenta formulation: 5% Cinquasia Magenta RT 235D

10% EFKA 4747 85% COASOL

In the formulation of Examples 6 to 10 inclusive, the amount shown of EFKA4747 is the actual amount of that product. It is used let down in a 35% solution in a portion of the COASOL used.

EXAMPLE 11 Magenta formulation: 5% Cinquasia RT 235D

10% EFKA4747

85% TPM

EXAMPLE 12

Red formulation: 5% Permanent Rubine F6B

10% EFKA4747 85% TPM EXAMPLE 13

Red formulation: 5% Hostaperm Red F6B

5% EFKA4747 90% TPM

EXAMPLE 14

Magenta formulation: 5% Sunfast Magenta 202

10% EFKA4747 85% TPM

EXAMPLE 15

Magenta formulation: 5% Sunfast Magenta 19 2280022

7% EFKA4747 88% TPM

EXAMPLE 16

Yellow formulation: 5% Irgazin Yellow 2 GLTE

5% EFKA4747 90% TPM

EXAMPLE 17

Yellow formulation: 5% Paliotol Yellow D0900

5% EFKA4747 90% TPM EXAMPLE 18

Yellow formulation: 5% Sandorin Yellow 4G

5% EFKA4747 90% TPM

All of the formulations of Examples 6 to 18 inclusive were found to be washfast when subjected to the foregoing wash test. All of those in Examples 11 to 18 inclusive had failed the test within 1 month. However, those of Examples 6 to 10 inclusive were stable after 1 month at 45 °C.

Regal 250R is a carbon black available from Cabot.

TPM is tripropylene glycol monomethyl ether.

EFKA 4747 is a film-forming polyurethane-based dispersant available from Efka Chemicals B.V.

Solsperse 12000 is a non-film-forming powdered dispersant synergist available from Zeneca Ltd.

COASOL is a mixture of the dibutyl esters of adipic, succinic and glutaric acids, available from Chemoxy International Company.

ESTASOL is a mixture of the dimethyl esters of adipic, succinic and glutaric acids.

Claims

1. A method of printing on textiles by ink jet printing using a dispersion ink comprising a dispersion of colorant in a non-aqueous liquid diluent, said dispersion further including a dispersant comprising a film-forming component.

2. A method as claimed in claim 1 characterised in that the ink has a viscosity not greater than 30 MPas and a surface tension in the range 27 to 72 dynes/cm.

3. A method as claimed in claim 1 or claim 2 characterised in that the diluent comprises at least one compound selected from ethers and esters.

4. A method as claimed in claim 3 characterised in that the diluent comprises at least one monoether of polyalkylene glycol .

5. A method as claimed in claim 4 characterised in that the diluent comprises tripropylene glycol monomethyl ether.

6. A method as claimed in claim 1 or claim 2 characterised in that the diluent comprises at least one diester selected from butyl esters of adipic, succinic and glutaric acids and mixtures thereof .

7. A method as claimed in any one of the preceding claims characterised in that the colorant forms from 2 to 20% by weight of the ink.

8. A method as claimed in any one of the preceding claims characterised in that the film-forming dispersant is water- immiscible.

9. A method as claimed in claim 8 characterised in that the film-forming water-immiscible dispersant is polymeric.

10. A method as claimed in claim 9 characterised in that the dispersant comprises a urethane polymer.

11. A method as claimed in any one of the preceding claims characterised in that the dispersant is employed in an amount of from 20 to 150 % by weight of the colorant.

12. A method as claimed in any one of the preceding claims wherein the textile is woven, knitted or lace and is selected from cotton, polyester, polyester/cotton mixes and polyester/rayon mixes.