Inkjet compositions and processes for stretchable substrates
Novel inkjet ink compositions for forming an image in a form of an elastic film attached to a surface of a stretchable and/or flexible substrate and processes utilizing same for inkjet printing color images on various substrates such as colored and absorptive or impregnable stretchable materials, which are characterized by heightened efficiency in process time, ink and energy consumption, as well as products having durable, wash-fast and abrasion-fast images printed thereon by the process, are disclosed. The novel ink compositions comprise a first part, which contains a property-adjusting agent and a carrier, and a second part which contains an emulsified property-sensitive proto-elastomeric film-forming agent, a colorant and a carrier, such that the second part congeals upon contact with the property-adjusting agent. The second part is digitally applied to the substrate less than 1 second following the application of the first part to the substrate.
1. An inkjet composition comprising a film-forming agent or binder, a pigment, and an aqueous carrier, the composition is characterized by a high pH level greater than 7, wherein the composition is for use in an inkjet printing process and congeals upon exposure to a low pH level below 7, and forms an elastic film upon drying/curing by heat, said film is characterized by high wash-fastness, and an elongation percentage of at least 30%.
2. The composition of claim 1 , wherein said low pH level ranges from 3.5 to 5.5.
3. The composition of claim 1 , wherein said film-forming agent or binder is characterized by a glass transition temperature (Tg) that ranges from −35° C. to 0° C.
4. The composition of claim 3 , wherein said film-forming agent or binder is selected from the group consisting of non-ionic water-emulsifiable resin, an acrylic polymer or copolymer, an alkyl-acrylic polymer copolymer, an acrylic-styrene copolymer, a polyurethane, a polyether, a polyester, a polyacrylate and ant combination thereof.
5. The composition of claim 4 , wherein said film-forming agent or binder is a self-crosslinking alkyl-acrylic copolymer.
6. The composition of claim 5 , wherein said self-crosslinking alkyl-acrylic copolymer is a formaldehyde-free crosslinking agent.
7. The composition of claim 5 , wherein said self-crosslinking alkyl-acrylic copolymer is an ethyl-acrylic/butyl-acrylic copolymer.
8. The composition of claim 1 , further comprising a crosslinking agent.
9. The composition of claim 8 , wherein said crosslinking agent is a formaldehyde-free crosslinking agent selected from the group consisting of a polyaldehyde, a heteroaryl polycarbamate, a diacetone acrylamide/hydrazine and a carbodiimide.
10. A process of digitally printing an image on a textile substrate, comprising:
applying a wetting composition to at least an ink receiving portion of the textile substrate to thereby obtain a wet substrate;
flattening said wet substrate using a flattening unit,
inkjet printing the image using the inkjet composition of claim 1 onto said portion, and
subsequent to said inkjet printing, drying/curing said image by heat,
thereby forming the image in a form of an elastic film characterized by an elongation percentage of at least 30%.
11. The process of claim 10 , wherein said wetting composition is an aqueous solution that comprises an acid.
12. The composition of claim 10 , wherein said property-adjusting agent is an organic acid.
13. The composition of claim 12 , wherein said acid is a transitory organic acid.
14. The composition of claim 13 , wherein said transitory organic acid is selected from the group consisting of lactic acid, glycolic acid, acetic acid and any combination thereof.
15. The process of claim 10 , wherein said applying is effected by spraying from a nozzle or by inkjet printing from an inkjet printhead.
16. The process of claim 10 , wherein said inkjet printing is effected while said wet substrate is still wet from said wetting composition.