ES2354544A1 - Catalytic system for the drying of inks and varnishes offset. (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Catalytic system for the drying of offset inks and varnishes. The present invention relates to a new catalyst system characterized in that it comprises: a) an envelope comprising at least one water-soluble polymer; and b) at least one inorganic catalyst inside said envelope. Likewise, the method of obtaining said catalytic system, as well as its application in printing machines for varnishes and offset inks, will be the object of the invention. (Machine-translation by Google Translate, not legally binding)

Description

Catalytic system for drying inks and offset varnishes

Technical field

The present invention relates to a new catalytic system to accelerate drying in printing machine of varnishes and offset inks.

Background of the invention

It is known that, in printing with varnishes and greasy inks, one of the mechanisms of ink drying is the Oxidative polymerization by oxygen of the air. This process of drying occurs when the oxygen molecules react with the double bonds present in the resins or fatty acids of the inks or varnishes, with the corresponding formation of hydroperoxides These highly reactive compounds favor polymerization or crosslinking of the components of the inks or varnishes, thereby accelerating the drying process of same.

In order to improve said drying process, It is common to use some type of catalyst, such as transition metal salts, the most common being octoates or cobalt and manganese naphthenates. However, an excessive Addition of this type of catalysts favors the formation of skins or films prior to ink printing or varnish, and even in the containers that contain them, once these They have been open.

Therefore, in recent years, they have sought new techniques capable of solving these types of problems and, at the same time, get a quick drying of the inks or varnishes Once printed. These techniques include, for example, the incorporation of curing catalysts to the papers that are going to be printed matter (JP 2005119162 A) or to the water of the printing process (JP 11020328 A).

Also, to get a performance Controlled catalysts in the field of inks and varnishes for offset printing, microencapsules of photochemical catalysts for UV curing (WO 03/006151 A1) as well as microencapsulated whose wrapping material consists, mainly in polyvinyl alcohol (JP 2001342392 A).

On the other hand, this use of microencapsules It is quite common in the field of inks and varnishes for offset. Thus, microencapsulated fragrances have been described (BR 2000000054 A) and color precursors (US 006042641 A), of humectants (DE 2113451 A), thermochromic (US 6669765 B2) or color generators for pressure copy papers (JP 58199187 TO).

Catalytic systems have also been described. based on microencapsulated metal catalysts of transition and even peroxides for curing resins of polyester in which catalyst release occurs by pressure or temperature changes (EP 0287288 A1) and even as curing agents immobilized in microcapsules (JP 05171200 TO).

It will therefore be the object of this invention, a new catalytic system capable of improving the printing process of offset varnishes and inks, in particular, with respect to time necessary for drying them. It will also be subject to invention the method of obtaining said catalytic system, as well As its application in varnish and ink printing machines offset.

It is noteworthy that all systems prior art catalysts have a limit of very limited applicability, demanding a compromise between the minimum amount of catalyst applicable to the ink or varnish that allows to achieve an adequate drying rate and quantity maximum of it, since an excess of it could cause solidification of the ink or varnish with the single opening of the container, by contact with the oxygen of the air. With the system catalytic of the present invention, there is no maximum limit of catalyst content in the ink or varnish, since the catalyst It is active only when the ink or varnish comes into contact with water, which happens only in the printing machine. That crucial advantage of the new catalytic system allows not only get inks and varnishes drying faster, but also a lot more stable over time, once the container has been opened. In addition, it allows to design hybrid inks and varnishes containing both the catalysts hitherto employed, no action conditioned on contact with water, like the new ones of the invention, with which efficiency is enhanced and speeds of printing hitherto unattainable.

Description of the invention

The present invention relates to a new catalytic system characterized in that it comprises: a) a wrapper comprising at least one water soluble polymer; and b) at least one inorganic catalyst inside said envelope.

In a preferred embodiment of the invention, the polymer will be characterized as one of the polymers used usually in aqueous solutions used for cleaning of printing machines such as dextrins or natural rubber

Preferably, the polymer will be about a polysaccharide, preferably natural rubber, and more preferably, from gum arabic or pullulana gum, but also starches, dextrin, inulin, pectins, alginates can be used and, of course, any other polysaccharide or gum soluble in Water.

On the other hand, the catalyst will consist of preferably, in at least one inorganic catalyst, more preferably, at least one transition metal or any derived from it. In a preferred embodiment, said metal of transition will be selected from a group consisting of nickel, palladium, platinum, rhodium, iridium, cobalt, chromium, titanium, copper, iron, manganese, vanadium, mercury, silver, zinc, cadmium, tungsten and molybdenum, or any combination of the above. In a even more preferred embodiment of the invention, said catalyst will consist of salts of transition metals previously preferably described cobalt octoates or naphthenates or manganese.

In the preparation of the catalytic system, this catalyst will preferably be used suspended or dissolved in the aqueous solution of the polymer that will constitute the wrap or, well dissolved in a solvent immiscible with water as, for example, vegetable or mineral oils and these dispersed in the aqueous solution of the polymer that will constitute the envelope.

Also, in a particular embodiment of the invention, the catalytic system may further comprise other compounds, preferably additives, ligands or salts and, especially, surfactants, compatibilizers and stabilizers

It will be, in turn, an additional object of the present invention a method for obtaining the system catalytic described above, which will consist of the microencapsulation of at least one catalyst inside a envelope comprising at least one water soluble polymer. From In this way, said method will be characterized by understanding:

to)

the dispersion of at least one inorganic catalyst in a solution of at least one water soluble polymer;

b)

the formation of an emulsion by agitation;

C)

the formation of the catalytic system comprising at least one inorganic catalyst inside a shell comprising at least one water soluble polymer; Y

d)

the recovery of the catalytic system as a solid powder.

In a preferred embodiment of the invention, the formation of the catalytic system of stage (c) will be carried out by spray on acetone, which will preferably be found at a temperature between 4 and 10 ° C. Likewise Preferably, the recovery of the catalytic system will be carried out by filtration

In a preferred embodiment of the invention, the method may, in turn, comprise an additional stage after step (d), which will consist of washing the system catalytic. This washing will preferably be carried out by three portions of cold acetone, preferably, at one temperature between 4 and 10 ° C, and one of hexane.

On the other hand, regarding stage (c), there are different possible embodiments at the time of carrying it out. In a preferred embodiment of the invention, said dispersion is carried out by spraying, preferably, through a three-channel or single-channel gun working with air at pressure between 1.5 and 2.5 bars.

In a particular embodiment of the invention, the solution comprising at least one water soluble polymer, as well as a solution that comprises at least one catalyst inorganic will be subjected, before spraying, to a Sonication stage This stage will be carried out, so preferred, inside a single channel micronizer by which both solutions will pass.

In turn, an additional particular embodiment of the invention may also comprise an initial preliminary stage of forming an emulsion from the solution comprising at least one water soluble polymer. Said emulsion may be formed, preferably, by adding at least one agent emulsifier, which may preferably consist of lauryl Sodium Sulfate and / or Tween 200. Next, a solution that comprise at least one inorganic catalyst will be added to this emulsion. In a particular embodiment of the invention, this emulsion may also be sonicated, preferably, for a time of 1.5 h, after which it will be introduced in the sprayer which will preferably comprise a single channel.

Similarly, in another particular embodiment of the invention, the method will comprise a previous initial stage of formation of an emulsion of the solution comprising at least one water soluble polymer, as well as the formation of an emulsion to from a solution comprising at least one catalyst inorganic, preferably, by using a solvent that will preferably consist of at least one aliphatic hydrocarbon.

Finally, an additional embodiment of the invention, may comprise the addition of at least one catalyst inorganic on an emulsion of a solution that includes the less a water soluble polymer, preferably, gum arabic or Pullulana rubber Said emulsion will be taken to a sprayer in Dry or "Dry Spray", with an inlet temperature, preferably, between 170 and 175 ° C and a temperature of preferential output between 100 and 115 ° C.

By regulating the conditions of said method of obtaining the catalytic system (or microencapsulation), it will be possible to control both the thickness of the envelope, such as the final size of the catalytic system (or microcapsules), size that will also depend on the method of dispersion used. So for example, in the case that said method is carried out by spraying on acetone, the size of The microcapsules will be between 50 and 200 µm, preferably between 10 and 50 µm, while the application of other methods, such as that carried out by micronization, allow to reach sizes between 0.5 and 10 µm, preferably, between 0.5 and 4 µm, and more preferably, between 0.5 and 3 µm.

It will also be an additional object of the invention an ink or varnish comprising the catalytic system object of the invention. The percentage of the catalytic system in the ink or varnish will depend on the rest of its components but In any case, you can enter quantities between 1 and 10 times superior to the contents of free catalyst commonly used in the inks. In fact, in a particular embodiment of the invention, mixed curing systems may be generated so that part of the catalyst used as an additive in the ink or varnish is find free and, the rest, is forming the catalytic system or microcapsule object of the invention.

Finally, it will also be the subject of the invention, the use of the catalytic system to accelerate the drying of varnishes and offset inks in printing machines.

During the printing process, once reach a temperature between 70 and 80 ° C, the envelope of The microcapsule will dissolve, thus releasing the catalyst included inside.

In turn, thanks to the features film-forming catalytic system, it will be possible to control the solubility of the system by preventing the release of the catalyst in fatty media, which will only be released when the system Catalytic be dissolved in water.

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Preferred Embodiment of the Invention

Below are presented, by way of example and without limiting the scope of the invention, a series of embodiments preferred thereof, specifically with respect to the method led to out to obtain the catalytic system object of invention:

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Example one

Microencapsulation of cobalt octoate by spraying using as gum arabic wrapping material

In order to carry out the method of microencapsulation of the present example, a gun of spray or spray with three entrances: a horizontal one, by which Pressurized air and two vertical ones circulated, through which it was introduced, through the external channel, the flow comprising the material of wrap (17% aqueous solution of gum arabic) and, by internal, the catalyst (in this case, 12% Co octoate in mineral oil).

These solutions were sprayed with a 2.5 bar air pressure on 500 ml of cold acetone at 4 ° C, stirring then vigorously during the spraying, and cooling in an ice bath until a temperature of 0 ° C. The catalytic system obtained, with a size between 50 and 200 µm, it was filtered and washed with three portions of cold acetone (3x50 ml) and one of hexane (1x50 ml).

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Example 2

Microencapsulation of cobalt octoate by micronization on acetone using arabic gum wrapping material, with sonication

In this case, a micronizer of a single channel through which 75 ml of a sonication was passed aqueous solution of 16% gum arabic and 15 ml of octoate 12% cobalt in vegetable oil, pulverized, as in the case above, on 11 of cold acetone at 4 ° C with strong agitation during spraying, then introduced on a ice bath until reaching a temperature of 0ºC.

The catalytic system thus obtained, with a size between 1 and 10 µm, was filtered off and washed with three portions of cold acetone (3x50 ml) and one of hexane (1x50 ml).

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Example 3

Microencapsulation of cobalt octoate by micronization on acetone using arabic gum wrapping material emulsified

To carry out this example, a emulsion by slowly adding 10 g of gum arabic over 25 ml of water, then adding 0.066 g of Sodium Lauryl Sulfate and 0.132 g of Tween 20 (polysorbate 20). Then the solution was sonicated and 3 ml of cobalt octoact was added at 12%, keeping the sonication for 1.5 h.

Subsequently, the emulsion was introduced in a single channel nebulizer using a pump peristaltic with a flow rate of 2 ml / m, being nebulized subsequently with air at a pressure of 2.5 bar over cold acetone at a temperature of 4 ° C. The catalytic system thus obtained, with a size between 1 and 7 µm, was filtered off and washed with cold acetone (3x50 ml) and one of hexane (1x50 ml).

Printing machine trials showed that it is possible to obtain a print speed twice as high to that obtained by carrying out the same method with the catalyst free in solution. In turn, the formation of skins was not detected, There were no other problems arising from printing.

Example 4

Microencapsulation of Manganese octoate on acetone using as gum arabic wrapping material, emulsifying both of them

In this example, an emulsion was prepared dissolving 7.5 g of gum arabic in 25 ml of water. Then, it added 0.076 g of Sodium Lauryl Sulfate and 0.122 g of Tween 20 and then 3.5 ml of an organic salt of 16% manganese in an aliphatic hydrocarbon CAS No. 64742-82-1. The emulsion obtained was then atomized with an air inlet flow rate of 1.5 bar above cold acetone at a temperature of 4 ° C, vigorously stirring the Mix during spraying. The catalytic system obtained, with a size between 1 and 5 µm, filtered and washed with cold acetone (3x50 ml) and then with hexane (50 ml).

In this case, the print tests in machine, showed how productivity increased on the order of 1.5 times with respect to the same method carried out with the catalyst free in solution.

Example 5

Microencapsulation of cobalt octoate using "Dry Spray "using as rubber wrapping material pullulana

An emulsion was prepared by adding 12 g of pullulana gum in 150 ml of water with vigorous agitation. Then, 0.39 g of sodium lauryl sulfate and 0.792 g were added of Tween 20 and finally, 37.5 g of octoate of cobalt with vigorous agitation for 1.5 h.

The emulsion obtained was then introduced in a spray gun "Dry Spray", at a temperature 175ºC inlet and 115ºC outlet temperature. The system final catalytic, with a particle size between 1 and 4 µm, It was obtained with yields between 40-45%.

Example 6

Microencapsulation of cobalt octoate by dry spray using as gum arabic wrapping material

In this example, an emulsion was prepared by adding in 150 ml of water 37.5 g of gum arabic, keeping it under stirring for 0.5 h. Then with vigorous stirring, 0.516 g of sodium lauryl sulfate and 0.672 g of Tween 20 and finally maintaining stirring for 1.5 h, 37.5 g of cobalt octoate were added.

The emulsion was then taken to a spray gun "Dry Spray", where it was introduced to a 170 ° inlet temperature and at 100 ° C outlet temperature. The catalytic system, with a particle size between 0.5 and 3 µm, was thus obtained with yields comprised between 55-60%.

As the previous examples reflect, thanks to the catalytic system obtained by any of the methods previously described it is possible, in all cases, to accelerate the drying process of inks and varnishes and at the same time prevents the formation of films in the containers that contain them, thus extending the durability of these products.

Claims (18)

1. Catalytic system characterized in that it comprises:

to)

a envelope comprising at least one water soluble polymer; Y

b)

to the less an inorganic catalyst inside said envelope.

2. Catalytic system according to claim 1, characterized in that the polymer consists of at least one polysaccharide. 3. Catalytic system according to claim 2, characterized in that the polysaccharide is a natural gum. 4. Catalytic system according to claim 1, characterized in that the inorganic catalyst is a transition metal or a derivative thereof. 5. Catalytic system according to any one of claims 1 or 4, characterized in that said inorganic catalyst is a transition metal selected from a group consisting of nickel, palladium, platinum, rhodium, iridium, cobalt, chromium, titanium, copper, iron, manganese, vanadium, mercury, silver, zinc, cadmium, tungsten and molybdenum, or any combination of the above. 6. Catalytic system according to any one of claims 1, 4 or 5, characterized in that the inorganic catalyst is a salt. 7. Catalytic system according to claim 6, characterized in that said salt is cobalt or manganese octoate or naphthenate. 8. Catalytic system, according to any one of the preceding claims, characterized in that it further comprises surfactants, compatibilizers and stabilizers. 9. Catalytic system, according to any one of the preceding claims, characterized in that the diameter thereof is between 0.5 and 10 µm. 10. Method of obtaining a catalytic system according to any one of the preceding claims, characterized in that it comprises the following steps:

to)

the dispersion of at least one inorganic catalyst in a solution containing at least one water soluble polymer;

b)

the formation of an emulsion by agitation;

C)

the formation of the catalytic system comprising at least one inorganic catalyst inside a shell comprising at least one water soluble polymer; Y

d)

the recovery of the catalytic system as a solid powder.

11. Method according to claim 10, characterized in that the formation of the catalytic system of step (c) is carried out by spraying on acetone. 12. Method according to claim 10, characterized in that the formation of the catalytic system of step (c) is carried out by dry spray. 13. Method according to any one of claims 10 or 11, characterized in that the recovery of the catalytic system is carried out by filtration. 14. Method according to any one of claims 10 to 13, characterized in that said method comprises an additional stage after stage (d) of washing the catalytic system. 15. Method according to claim 14, characterized in that said washing of the catalytic system is carried out with three portions of cold acetone and one of hexane. 16. Method according to claims 11 and 12, characterized in that it comprises an additional stage, prior to spraying, of sonication of the solution comprising at least one water soluble polymer and of a solution comprising at least one inorganic catalyst 17. Ink or varnish characterized in that it comprises the catalytic system according to any one of claims 1 to 16. 18. Use of the catalytic system according to a any of claims 1 to 17 to accelerate the drying of varnishes and offset inks.