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The present invention provides low migration radiation-curable inks and coatings for the printing of food, pharmaceutical and other sensitive packaging materials, having one or more polymerizable monomers or oligomers and one or more type-I photoinitiators wherein the monomers or oligomers have an alkoxylated chain and at least 2 polymerizable groups per molecule and wherein the degree of alkoxylation per polymerizable group is 2 or greater.
This application claims priority to U. Provisional Patent Application Ser. The present invention is directed to the use of highly alkoxylated monomers or oligomers to increase the degree of monomer conversion during curing so as to result in a reduction of free and unbound monomer which can subsequently migrate into sensitive packaged goods, such as food and pharmaceutical products. Cattaneo et. EP 2 A1 is directed to radiation curable inkjet inks and industrial inkjet printing methods.
Finally EP 2 B1 is directed to scratch resistant radiation curable inkjet inks containing a photoinitiator. The present invention is directed to a low migration radiation curable ink or coating composition comprising;. Furthermore the present invention also provides a method of reducing the amount of migratable monomer in cured ink or coating composition comprising curing an ink or coating composition as mentioned herein above.
Finally the present invention provides a process for preparing an article with a coating or an ink printed thereon which comprises applying the ink or coating composition to a surface of an article and curing the composition. These and other objects, advantages, and features of the invention will become apparent to those persons skilled in the art upon reading the details of the methods and formulations as more fully described below.
It has been found that the use of highly alkoxylated monomers or oligomers increases the degree of monomer conversion during curing so as to result in a reduction of free and unbound monomer which can subsequently migrate into sensitive packaged goods, such as food and pharmaceutical products.
It has also been found that as the degree of alkoxylation increases the amount of unreacted monomer in the cured composition decreases. Furthermore the compositions according to the present invention have between 0. The compositions according to the present invention also have one or more type-I photoinitiators. The monomers or oligomers have an alkoxylated chain and at least two polymerizable groups per molecule wherein the degree of alkoxylation per polymerizable group is 2 or greater and preferably have at least 3 polymerizable groups per molecule.
The monomer or oligomer is typically ethoxylated, propoxylated or butoxylated. Typically the degree of alkoxylation per polymerizable group is 3 or greater, preferably 4 or greater and most preferably 5 or greater. The degree of alkoxylation for highly alkoxylated monomers or oligomers such as ethoxylated or propoxylated trimethylolpropane triacrylates TMPTA , polyethylene glycol diacrylates and polypropylene glycol diacrylates is shown below.
Preferably the polymerizable group is an acrylate, methacrylate, vinyl ether, allyl ether, maleate, fumarate, ethylenic, acrylamide, meth acrylamide, or epoxy group. Advantageously the polymerizable group is is an acrylate or a methacrylate group. The alkoxylated monomers or oligomers are usually formed by reacting polyol cores with alkene oxides such as ethylene oxide to produce alkoxylated polyols.
For example, trimethylol propane, a trihydric polyol core can be reacted with ethylene oxide to form the ethoxylated polyol derivative. When this is subsequently esterified with acrylic acid the resultant product is the acrylated monomer shown below;. It is further preferred that the functionality of the monomer or oligomer with respect to the polymerizable groups is 2 or greater. The monomer or oligomers are typically selected from meth acrylate adducts of ethoxylated, propoxylated or butoxylated derivatives of trimethylol propane, pentaerythritol, dipentaerythritol, neopentyl glycol, glycerol, ethylene glycol, propylene glycol, butanediol, higher alkane diols and sugars such as sucrose.
Other alkoxylated monomers include the diacrylates of polyethylene glycol and polypropylene glycol. Highly alkoxylated oligomers may also include those derived from alkoxylated, and in particular, the ethoxylated derivatives of bisphenol. Furthermore, the monomers or oligomers may be produced by esterification of meth acrylic acid with alkoxylated polyol cores or polyurethane meth acrylate oligomers based on highly alkoxylated cores.
These types of oligomers, known as polyether urethane acrylates can be prepared, for example, by reacting an alkoxylated polyol core, such as poly ethylene glycol, with a diisocyanate such as isophorone diisocyanate and a hydroxyl-functional acrylate, such as hydroxyethyl acrylate.
The monomer or oligomer is advantageously an acrylate adduct of the ethoxylated derivative of trimethylol propane, pentaerythritol, dipentaerythritol, glycerol, neopentyl glycol, ethylene glycol, propylene glycol or bisphenol. Alternatively the monomer or oligomer is advantageously an acrylate adduct of a propoxylated derivative of trimethylol propane, pentaerythritol, dipentaerythritol, glycerol, neopentyl glycol, ethylene glycol or propylene glycol.
In a preferred embodiment the monomer or oligomer is an ethoxylated or propoxylated trimethylolpropane triacrylate, polyethylene glycol diacrylate or polypropylene glycol diacrylate. The composition may contain at least one polymeric photoinitiator. The composition may also contain at least one type-II photoinitiator.
The composition usually has less than 2. The photoinitiators used in the compositions according to the present invention are preferably those recognized as having low migration potential which are suitable for the preparation of inks for the printing on the non-contact side of food packaging, as defined by EuPIA's guidelines. It is also possible to incorporate other non-low migration potential photoinitiators into the compositions of the present invention.
In particular, any photoinitiators used in the compositions according to the present invention preferably exhibit a migration of less than 10 ppb. In addition the highly alkoxylated monomers or oligomers may comprise as part of their chemical structure other polymerizable groups, or blends thereof, such as vinyl ether, allyl ether, maleate, fumarate, ethylenic, acrylamide, meth acrylamide, epoxy and any other reactive group that is polymerizable by a free radical or ionic propagation process.
The compositions may contain suitable colorants which include, but are not limited to organic or inorganic pigments and dyes.
The dyes include but are not limited to azo dyes, anthraquinone dyes, xanthene dyes, azine dyes, combinations thereof and the like. Other organic and inorganic pigments and dyes can also be employed, as well as combinations that achieve the colors desired. The compositions according to the present invention may also contain other components which enable them to perform in their intended purpose. These components include, but are not restricted to; stabilizers, wetting aids, slip agents, inert resins, antifoams, fillers, rheological aids, amine synergists, etc.
The compositions of the present invention may also contain an inert resin such as an acrylic polymer. Finally the compositions according to the present invention typically have viscosities of less than The compositions according to the present invention are radiation curing ink or coating compositions that contain reactive groups which react with each other after exposure to energy-rich radiation. The compositions may be cured using an electron beam EB but are preferably cured using ultraviolet light UV.
Advantageously, the compositions can be UV-cured by an actinic light source, such as UV-light, provided by a high-voltage mercury bulb, a medium-voltage mercury bulb, a xenon bulb, a carbon arc lamp, a metal halide bulb, a UV-LED lamp, a uv laser, such as a semiconductor laser or an eximer laser, or sunlight.
The compositions according to the present invention can be applied to the non-food contact surface of food packaging including primary and secondary food packaging. Typically the compositions are applied to the surface of a plastic film, or a paper or paperboard substrate. The plastic film can be any of the following; polyester, polyethylene, polypropylene, polyamide, poly lactic acid , a cellulose film and any coated or pretreated film thereof.
A printed plastic film may subsequently be laminated to a second or more plastic film, to form a printed laminate film suitable for food packaging. A printed paper or paperboard substrate may subsequently be laminated to a second or more plastic film, to form a printed laminate suitable for food packaging. The ink or coating compositions are typically applied to the articles using inkjet, flexo, gravure, screen, and litho printing. The state of the art considers that in order to achieve the highest conversion of monomer during curing and thus the lowest level of monomer migratables, the composition must incorporate monomers or oligomers having a high polymerizable group concentration per molecule such as compounds having at least 3 or more polymerizable groups per molecule, such as the penta and hexaacrylated adducts of dipentaerthyritol.
This presumes that the higher the concentration of polymerizable group per molecule results in a higher crosslinking density.
However, it has been found that the incorporation of highly ethoxylated trifunctional monomers, such as ethoxylated TMPTA having greater than 6 moles of ethoxylation, into ink or coating compositions can deliver significantly lower levels of unreacted monomer than is achievable with an equivalent weight concentration of dipentaerythritol pentaacrylate, even though the latter composition would have a significantly higher concentration of acrylate groups than a composition containing the highly ethoxylated TMPTA.
Furthermore it has also been found that the incorporation of highly ethoxylated difunctional monomers, such as poly ethylene glycol diacrylates can also deliver lower levels of unreacted monomer. It is believed that the advantages of introducing such monomers or oligomers into the coatings or compositions according to the present invention is that they enable greater segmental mobility for the polymerizable groups during the curing process allowing for more residual unsaturated monomer sites that are available for polymerization, leading to higher conversion of the monomers and oligomers in the curing composition.
Furthermore it has been found that incorporating highly alkoxylated monomers into the compositions according to the present invention allows for lower concentrations of photoinitiator which reduces the risk associated with migration of unbound photoinitiator or photoinitiator decomposition products, even where low migration potential photoinitiators are employed.
This is particularly advantageous for UV-inkjet compositions because typically relatively high concentrations of photoinitiators are required to help overcome the effect of oxygen inhibition, which is an endemic problem associated with the UV-curing of inkjet compositions in air.
Furthermore, since printed inkjet films are typically very much thicker than would be the case with flexo, gravure or offset applied inks, then the amount of photoinitiator used per unit area of food packaging is even higher. This can even be achieved for inks which are cured in air wherein for most applications, nitrogen inerting may be preferred during curing, but the inks and coatings of the present invention could be cured either with or without inerting.
The following examples illustrate specific aspects of the present invention and are not intended to limit the scope thereof in any respect and should not be so construed.
The inks were prepared by mixing the pigment dispersion with the ink components using a Silverson type disperser for 20 minutes.
The inks were then filtered to remove any oversized particles that might be present in the ink. This test involved soaking 30 cm 2 of the print in 2 ml of methanol, containing 0. The GC-MS was calibrated with known solutions of the monomers and photoinitiator products and the results are reported as ppb, the equivalent amount of monomer that would be present in 1 Kg of food according to the EU packaging model where it is assumed that cm 2 of substrate is required to package 1 Kg of food if all the unbound monomer in the print were to migrate into and contaminate the food.
The poly ethene film was then extracted into 2 ml of methanol, containing 0. Similarly, the results are reported as ppb, the amount of migratable material that would be present in 1 Kg of food according to the EU packaging model, where it is assumed that cm 2 of substrate is required to package 1 Kg of food. Inks Comparative Examples 1 to 5 and Inventive Example 1 were prepared with compositions according to the following:. Table 2 provides the details of the monomers used in the preparation of Comparative Examples 1 to 5 and the monomer used in Inventive Example 1.
Table 2 shows that Inventive Example 1, having the ethoxylated trimethylolpropane triacrylate having a degree of ethoxylation of 15, is much more effective than the other monomers in delivering low levels of extractable monomer from cured ink films. It is significantly more effective than the pentaacrylate adduct of dipentaerythritol Comparative Example 1 and also more effective than the ethoxylated trimethylolpropane adduct having a degree of total ethoxylation of 3 Comparative Example 2.
This latter monomer is one commonly used in the preparation of radiation-curable inks and it would be expected according to the state of the art that due to its higher acrylate density to deliver lower levels of extractable monomer from a cured ink film than would the analogous monomer having around 15 moles of total ethoxylation. Inventive Example 1 demonstrates the advantage of incorporating a highly alkoxylated monomer into a radiation-curable ink intended for low migration applications.
Comparative Examples 6 and 7 and Inventive Examples 2 and 3, along with Comparative Example 2 show that it is preferable that the degree of alkoxylation, in this case the degree of ethoxylation on a trimethylolpropane core, should preferably be greater than 2, on average, per acrylate moiety. These examples were prepared according to the ink composition provided above. Inventive Examples 1 to 3 show that a degree of ethoxylation per acrylate moiety in excess of 2 i.
The extent by which the level of extractable monomer decreases when moving from a degree of ethoxylation per acrylate moiety of 2 to 3 is particularly pronounced.
In this series of experiments the amount of extracted NPG PO DA is also provided to further demonstrate the effect that the introduction of highly alkoxylated monomers has in lowering the amount of unbound monomer in UV-cured inkjet films after extraction into methanol. The results in Table 5 indicate that even a small addition of a highly alkoxylated monomer can significantly reduce the amount of unbound monomer which can be extracted from a UV-cured inkjet film.
The examples provided thus far are based on the highly ethoxylated derivatives of trimethylolpropane triacrylate. To demonstrate that the effect is also achievable using monomers of lower functionality, a series of white inks comprising PEGDAs having PEG cores of different molecular weight were prepared according to the following composition.
A white dispersion is a dispersion containing The results in Table 7 show that introducing PEGDA into a white UV-curable inkjet composition reduces the amount of unbound, unreacted monomer in a UV-cured film as evidenced by the amount of monomer that can be extracted into methanol. In a further experiment.
To demonstrate this, cyan inkjet ink compositions were prepared with 3. Two inks demonstrating the invention containing Also determined in these examples was the amount of extractable mesitaldehyde, which is a photodecomposition by-product from the phosphine oxide photoinitiator, Irgacure The results provided in Table 9 demonstrate that at the same photoinitiator level, the compositions according to the present invention can produce lower levels of unbound, unreacted monomer in UV-cured films compared with the comparative examples.
This has the benefit of optionally being able to reduce the amount of photoinitiator and hence any photodecomposition by-products available for migration. It is also possible to prepare inks according to the current invention which comprise polymeric photoinitiators in conjunction with Type-I photoinitiators.
Table 10 provides the compositions for 2 inks comprising alkoxylated monomers according to the current invention, along with a polymeric photoinitiator, Omnipol TX ex.
Acrylated Amine A is a proprietary acrylated amine. The present invention has been described in detail, including the preferred embodiments thereof.
A composition according to claim 1 wherein the one or more photoinitiators have a low migration potential.
LOW MIGRATION RADIATION CURABLE INKS
UV-curing of clear Epoxy-Acrylate Coatings. UV-curing of clear Polyester-Acrylate Coatings. Patent documents cited in the description. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid.
Raw Material Strategies for Food Packaging Compliance
The present invention provides low migration radiation-curable inks and coatings for the printing of food, pharmaceutical and other sensitive packaging materials, having one or more polymerizable monomers or oligomers and one or more type-I photoinitiators wherein the monomers or oligomers have an alkoxylated chain and at least 2 polymerizable groups per molecule and wherein the degree of alkoxylation per polymerizable group is 2 or greater. This application claims priority to U. Provisional Patent Application Ser. The present invention is directed to the use of highly alkoxylated monomers or oligomers to increase the degree of monomer conversion during curing so as to result in a reduction of free and unbound monomer which can subsequently migrate into sensitive packaged goods, such as food and pharmaceutical products. Cattaneo et.
The present disclosure relates to medical devices which have a substrate including a hydrophilic coating thereon. More particularly, the present disclosure relates to medical devices for insertion into a body and, even more particularly, medical devices for insertion into lumens or passageways of the body, e. The present disclosure also relates to methods of using and making such medical devices. In the medical field, and in other fields as well, the surface of a device may be coated with a hydrophilic coating that becomes lubricious upon contact with water to ease insertion of the device into the body.