Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2002-11-13
2004-05-04
Berman, Susan (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S075000, C522S079000, C522S080000, C522S084000, C522S096000, C522S097000, C106S031570, C106S031580, C524S356000, C524S366000, C524S379000
Reexamination Certificate
active
06730714
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to low viscosity, ink jettable, radiation curable compositions incorporating limited quantities of solvent to provide the compositions with viscosity, wettability, compatibility, and rapid curing advantages. The compositions generally include a radiation curable component (containing one or more radiation curable monomers, macromers, oligomers, and/or polymers), a solvent, and optional additives such as colorants, photoinitiators, and the like. The compositions are particularly well-suited for forming ink jetted, radiation cured printed features on substrates such as signs, walkways, roadways, motor vehicles, boats, aircraft, furniture, equipment, and the like. The compositions are particularly well-suited for use in outdoor applications.
BACKGROUND OF THE INVENTION
Inkjet imaging techniques have become very popular in commercial and consumer applications. Ink jet printers operate by ejecting ink onto a receiving substrate in controlled patterns of closely spaced ink droplets. By selectively regulating the pattern of ink droplets, ink jet printers can produce a wide variety of printed features, including text, graphics, images, holograms, and the like. Moreover, ink jet printers are capable of forming printed features on a wide variety of substrates, as well as three-dimensional objects in applications such as rapid prototyping.
Thermal ink jet printers and piezo inkjet printers are the two main types of ink jet systems in widespread use today. For both approaches, inks must meet stringent performance requirements in order for the inks to be appropriately jettable and for the resultant printed features to have the desired mechanical, chemical, visual, and durability characteristics. In particular, inks must have relatively low viscosity when jetted, yet must be able to form accurate, durable images on the desired receiving substrate. For example, a typical ink for thermal ink jetting must typically have a viscosity in the range of 3 to 5 centipoise at 25° C., while piezo inks must typically have a viscosity in the range of 3 to 30 centipoise at the jetting temperature. The need to use low viscosity inks makes it challenging to obtain printed features with good mechanical, chemical, visual, and durability characteristics.
Solvent-based and water-based jettable inks are well known. A typical water-based ink generally comprises water, a colorant, which may be a dye and/or a pigment, one or more co-solvents, and one or more additives that are included to enhance the performance of the ink. Representative examples of such additives include one or more colorants, slip modifiers, thixotropic agents, foaming agents, antifoaming agents, flow or other rheology control agents, waxes, oils, plasticizers, binders, antioxidants, fungicides, bactericides, organic and/or inorganic filler particles, leveling agents, opacifiers, antistatic agents, dispersants, and the like.
Water-based inks have drawbacks. For industrial applications, drying is energy and equipment intensive. Drying water also takes time, and the printed material needs to be handled carefully during the relatively lengthy drying period. Water-based inks are also compatible only with a limited range of substrates, typically those on which the water is absorbed to some degree. Images formed using water-based inks typically require a protective overlaminate for outdoor applications.
Instead of water, other solvent-based inks include relatively volatile, inorganic solvents. Such inks dry more rapidly and easily than aqueous inks. However, such solvents may be toxic, flammable, or the like, requiring careful handling. These inks also tend to be compatible with only a limited range of substrates.
In order to avoid using a conventional solvent, ink compositions incorporating a free radically polymerizable diluent have been developed. The diluent not only functions as a solvent, but also functions as a viscosity reducer, as a binder when cured, and optionally as a crosslinking agent. In the uncured state, these compositions have a low viscosity and are readily jetted. However, the polymerizable monomers readily crosslink upon exposure to a suitable source of curing energy, e.g., ultraviolet light, electron beam energy, and/or the like, to form a crosslinked polymer network. Depending upon the kind of monomers incorporated into the diluent, the resultant network may provide the printed features with durability, flexibility, elasticity, gloss, hardness, chemical resistance, stiffness, combinations of these, and the like.
There are many instances in which relatively large amounts of solvent have been incorporated into radiation curable ink compositions. For example, EP 407,054 (1990) and U.S. Pat. No. 4,978,969 each describe radiation curable ink jet inks containing 10 to 40 weight percent of solvent. JP 9-314981 (1997) describes ink jet inks containing greater than 40 weight percent of methyl ethyl ketone (MEK) solvent. U.S. Pat. No. 5,623,001 describes radiation curable ink jet inks containing 20 to 75 weight percent water. The use of ink compositions containing relatively large amounts of solvent that might require separate drying steps is desirably avoided.
There are other instances in which relatively little if any solvent has been incorporated into radiation curable ink compositions. For example, EP 540,203 (1993) and U.S. Pat. No. 5,275,646 describe radiation curable compositions with no solvent. JP 9-183929 (1997) and WO 98/27171 also describe solvent-free compositions. WO 99/29787 and 99/29788 both describe radiation curable ink jet inks containing less than 1% solvent.
WO 97/31071 (corresponding to U.S. Pat. No. 6,114,406) also describes ink jet inks with limited solvent content. The document generically suggests that the inks may contain up to about 10 weight percent solvent, but the examples only describe ink formulations that do not include any solvent. The compositions also must include major amounts of alkoxylated or polyalkoxylated material, but unfortunately such compositions tend to have poor weatherability, adhesion, and compatibility characteristics due to the high alkoxylated content in the main chain(s) of the resultant cured matrix.
Substrate compatibility is an important characteristic of radiation curable compositions, particularly for industrial or signage applications in which printed features may be formed upon a wide variety of different substrate materials. However, many radiation curable compositions show good wettability and adhesion to only a limited range of substrates, requiring maintenance of several different kinds of inks in those environments in which a wide variety of substrates are likely to be encountered. Many radiation curable ink compositions, particularly those incorporating significant quantities of main-chain alkoxylated or polyalkoxylated functionality, also suffer from poor weatherability in outdoor applications. It would be desirable to provide ink jet inks that are compatible with a wide range of different porous and nonporous substrates.
Rapid curing of radiation curable compositions is highly desirable to increase production capacity and throughput. However, oxygen in the ambient can have a tendency to inhibit free radical polymerization reactions. While oxygen inhibition can be avoided by curing materials in an inert atmosphere, maintaining an inert atmosphere during cure involves extra equipment and expense. Curing in an inert atmosphere also may not be practical in some applications. Accordingly, it would be highly desirable to provide ink jet inks that cure rapidly in the ambient and for which the risk of oxygen inhibition in the ambient is significantly reduced. It would be even more desirable if such curing could be carried out without resort to an inert atmosphere.
Ink jet compositions also require good dot gain characteristics. Dot gain refers to the degree to which an ink jetted drop spreads out upon application to a substrate. If an ink jetted drop spreads out too much on the substrate, then poor edge definition and interc
Severance Richard L.
Thery Ronald K.
Ylitalo Caroline M.
3M Innovative Properties Company
Berman Susan
LandOfFree
Inks and other compositions incorporating limited quantities... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Inks and other compositions incorporating limited quantities..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Inks and other compositions incorporating limited quantities... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3197923