WO2000002965A1

WO2000002965A1 - Water based dispersion of solid particles containing uv absorbing components as active ingredients, and method for obtaining such a dispersion

Info

Publication number: WO2000002965A1
Application number: PCT/IB1998/001064
Authority: WO
Inventors: Fortunato Joseph Micale
Original assignee: Fortunato Joseph Micale
Priority date: 1998-07-13
Filing date: 1998-07-13
Publication date: 2000-01-20
Also published as: AU7927898A

Abstract

A method for obtaining a water based dispersion of solid particles containing UV absorbing components as active ingredients comprises the following steps: a) heating an encapsulating matrix above its melting point; b) dissolving an UV absorbing material in the melted encapsulating matrix; c) heating water to the same temperature as the encapsulating matrix; d) adding a suitable surfactant in a predetermined quantity to the heated water; e) emulsifying the heated solution comprising the UV absorbing material; f) cooling down the emulsified mixture in order to obtain the formation of a uniform mixture of solid particles containing said UV absorbing components. The resulting water based dispersion may either be formulated in a gravure ink, or be added to a gravure ink that does not contain pigment, or be incorporated in a coating.

Description

WATER BASED DISPERSION OF SOLID PARTICLES

CONTAINING UV ABSORBING COMPONENTS AS ACTIVE

INGREDIENTS, AND METHOD FOR OBTAINING SUCH A DISPERSION

********

TECHNICAL FIELD

The present invention relates to a water based dispersion of solid particles containing UV absorbing components as active ingredients.

Furthermore, the present invention relates to a method for obtaining such a water based dispersion.

The water based dispersion according to the present invention has a particularly useful application for printing ink and coating industries.

BACKGROUND ART It is known in the art that effective UV absorbing materials are constituted by organic molecules which are tipically insoluble in water.

By way of example, in the cosmetic industry UV absorbing materials are normally used as creams which are constituted by oil in water emulsions, whereby UV absorbing materials are dissolved in the oil phase.

This mode of application, i.e. an oil in water emulsion, is not suitable for producing printing inks; in fact, in this case solvent inks should be used in order to dissolve the UV absorbing material in the oil based solvent .

Furthermore, a very high concentration of the UV absorbing material generally used in the cosmetic industry would be necessary to obtain printed films featuring acceptable UV absorbing properties.

Since said UV absorbing materials are rather expensive, they can hardly be used for this kind of applications.

UV absorbing materials used in sunscreens are normally constituted by liquids and include benzophenones and anthranilates for long wave length absorption and PABA derivatives and salicylates for short wave length absorption.

In the field of bottling and packaging of bottles, prior to the advent of P.E.T. (Polyethylene Terpolymer) the bottle labels were made of paper and applied at a rate of 600 to 1.000 labels a minute. With the introduction of plastic bottles, plastic labels consisting of a layer of voided polyethylene on which an ink layer is applied have been used, whereby a polypropylene layer is then spread on said ink layer. This results in a rather expensive product. Owing to the limited solubility of organic molecules provided with UV absorbing properties, there is at present no effective water based ink available as UV protective coating.

Document US-A-4 , 945 , 121 discloses a process characterized by dissolving a dye in a solution of organic solvent and an epoxy type polymer, which requires a curing agent in order to create a resultant nanosphere that will crosslink through the action of the curing agent, and not simply as the result of a solvent removal which defined each nanosphere.

The dye may be in concentration range of 1% to 50% by weight of solvent, and the organic solvent must have limited solubility in water, typically less than 20%.

An initial intermolecular mixing step dissolves dye and epoxy resin within a solvent so as to make a homogeneous solvent/polymer/dye intermediate mixture, that then is dispersed as nanoparticles in water, and thereafter crosslinked. Surfactants may be used to assist in dispersing the dye/polymer/solvent solution into the water continuous phase .

According to this document, the invention can also be used for UV absorbers; however, the process according to this document involves an intermediate solvent which requires that the active ingredient and the encapsulating matrix be soluble in the solvent.

After emulsification into small liquid drops, the solvent must be extracted to form a stable dispersion of solid particles.

Although this works quite well with a number of materials for methylene chloride as a solvent, this solvent was later put on the EPA list of undesirable solvents . This constitutes a fundamental drawback of this process, since the particles resulting from said process contain significant amounts of methylene chloride, which could not be entirely extracted.

Many searches have been carried out for several years in order to single out a substitute solvent, but no one has been found with the same desirable properties, especially for commercial production.

DESCRIPTION OF THE INVENTION The present invention aims to set aside the disadvantages and drawbacks which are typical of the background art, and to provide, thus, for a water based dispersion of solid particles containing UV absorbing components as active ingredients which can be formulated into a cost effective water based ink or coating exhibiting very strong UV absorbing characteristics, whereby the dispersion does not contain any trace of methylene chloride.

This is achieved by means of the water based dispersion disclosed in claim 1.

The dependent claims disclose particularly advantageous forms of embodiment of the water based dispersion according to the invention.

Furthermore, the present invention aims to provide for a method for obtaining such a water based dispersion, whereby no intermediate solvent is used.

This is achieved by carrying out the steps disclosed in claim 8.

The claims dependent on this claim outline particularly advantageous forms of embodiment of the method according to the invention.

The dispersion according to the present invention consists of colloidally stable submicron particles dispersed in water, i.e. particles which have a diameter which is predominantly less than one micron, said dispersion consisting of an active ingredient, in particular a UV absorbing material, encapsulated into a protective matrix.

A typical particle size range according to the invention is 0,05 microns to 5,0 microns.

According to the invention, said active ingredient is constituted by an UV absorbing organic molecule which is not soluble in water and which can be liquid or solid at room temperature. According to a particularly advantageous form of embodiment of the present invention, the organic UV absorber is UV-Chek AM-300® (Polymer Additives Division Ferro Corporation - 7050, Krick Road - Walton Hills - Ohio - U.S.A.). Organic UV absorber UV-Chek AM-300® is 2-Hydroxy-4-n- Octyloxybenzophenone and is a strong UV absorber over a wide range of the UV spectrum; it is solid at room temperature (melting point: 47°C) and is compatible with a plurality of low melting point encapsulating matrices which are very good solvent for said organic UV absorber.

UV-Chek AM-300® is an effective UV light absorber for wide variety of polymers, and it features especially effective UV absorbing properties in polyolefins; it is normally used as costabilizer in polyolefin films for agricultural and greenhouse use, as well as light stabilizer for flexible and semi-rigid PVC coatings.

Another organic UV absorbing material which can be used for carrying out the present invention is constituted by Escalol 567®, i.e. 2-Hydroxy-p-methoxybenzophenone

(produced by ISP Van Dyk Corporation - 11 Williams Sts. -

Belleville - NJ 07109 - U.S.A.).

Yet, another organic UV absorbing material which can be used for carrying out the present invention is constituted by Escalol 587®, i.e. Octyl-Salicylate (ISP

Van Dyk Corporation - 11 Williams Sts. - Belleville - NJ

07109 - U.S.A. ) .

According to the invention, the encapsulating matrix consists of a material having a relatively low melting point, i.e. less than 100°C, which is not soluble in water and compatible with the active ingredient, or at least a very good solvent for it .

Typically, said material can be constituted by, e.g. commercial paraffin, bees wax, low molecular weight polyethylene.

According to a particular form of embodiment of the invention the UV absorber to encapsulating matrix ratio range is 1/20 to 10/1. The method for obtaining a water based dispersion including the UV material encapsulated m the matrix comprises the following steps.

An encapsulating matrix, insoluble m water and solid at room temperature, and preferably made of, e.g. commercial paraffin, bees wax, low molecular weight polyethylene is heated above its melting point.

Then the active ingredient, i.e. the UV absorbing material, is dissolved in the melted encapsulating matrix. A suitable surfactant like, e.g. Triton X-100®, i.e.

Octylphenooxypolyethoxyethanol (Union Carbide Corporation

- 39 Old Ridgebury Road - Danbury - CT 06817-0001 -

U.S.A.), or Span 80®, i.e. Sorbitan monooleate (ICI

Surfactants - Concord Plaza/Bedford Building - 3411 Silverside Road - P.O. Box 15391 - Wilmington - DE 19850 -

U.S.A.), or Span 85®, i.e. Sorbitan trioleate (ICI

Surfactants - Concord Plaza/Bedford Building - 3411

Silverside Road - P.O. Box 15391 - Wilmington - DE 19850 -

U.S.A.) , is added to water which is heated to the same temperature as the encapsulating matrix.

Then the heated solution, which contains the UV absorbing material dissolved in the encapsulating matrix, is emulsified m water by a suitable emulsifier apparatus, e.g. an ultra-sonic probe or a Mantm Gaulm homogenizer. The combination of the surfactant, which controls the surface tension, and the emulsifying apparatus, which controls the energy input, dictates the particle size distribution of the initial emulsion.

A subsequent cooling phase results m the formation of solid predommanty submicron particles which have been formulated to be of a controlled particle size and stable m water.

Such a water based dispersion consists of solid particles which contain an uniform mixture of active ingredient, i.e. UV absorbing material, at a cost effective concentration in the encapsulating matrix.

According to the invention, such a dispersion has a particularly interesting application in the bottle labels printing industry, since the dispersion is either suitable for formulation into a gravure ink, or may be added to a gravure ink which does not contain pigment, or may also be incorporated into a coating which would then offer both physical and UV protections. The invention will be better explained and understood by reading the following examples of different forms of embodiment .

EXAMPLE I 10 g of UV-CHEK AM-300® is dissolved into 20 g of a commercial paraffin which has been melted at 60°C.

This solution is emulsified for two minutes by means of an ultra-sonic probe in a water solution containing 0,1 g of Triton X-100® which is heated to 60°C.

The resulting emulsion is cooled to room temperature to form a stable dispersion in water of solid, but relatively soft, particles which absorb UV radiation.

Microscopic examination reveals that the particles are predominantly less than one micron.

The active ingredient to matrix ratio for this formulation is 1/2, and has been varied over the range of 1/20 to 10/1.

EXAMPLE II 10 g of UV-CHEK AM-300® is dissolved into 20 g of a commercial bee wax which has been melted at 90°C. This solution is emulsified for two minutes by means of an ultra-sonic probe in a water solution containing 0.1 g of Span 80® which is heated to 90°C. The resulting emulsion is cooled to room temperature to form a stable dispersion in water of solid, but relatively hard, particles which absorb UV radiation.

EXAMPLE III 10 g of Escalol 567® is dissolved into 20 g of a commercial paraffin which has been melted at 60°C.

This solution is emulsified for two minutes by means of an ultra-sonic probe in a water solution containing 0,1 g of Triton X-100® which is heated to 60°C. The resulting emulsion is cooled to room temperature to form a stable dispersion in water of solid, but especially soft, particles which absorb UV radiation.

Microscopic examination reveals that the particles are predominantly less than one micron. The active ingredient to matrix ratio for this formulation is 1/2, and has been varied over the range of 1/20 to 1/5.

EXAMPLE IV 10 g of UV-CHEK AM-300® is dissolved into 20 g of a low molecular weight polyethylene which has been melted at 90°C.

This solution is emulsified for two minutes by means of an ulta-sonic probe into 70 g of a water solution containing 0,1 g of Span 85® which is heated to 90°C. The resulting emulsion is cooled to room temperature to form a stable dispersion in water of solid and very hard particles which absorb UV radiation.

Microscopic examination reveals that the particles are predominantly less than one micron. The active ingredient to matrix ratio for this formulation is 1/2, and has been varied over the range of 1/20 to 2/1.

EXAMPLE V 10 g of Escalol 567® is dissolved into 20 g of a low molecular weight polyethylene which has been melted at 90°C.

This solution is emulsified for two minutes by means of an ultra-sonic probe into 70 g of a water solution containing 0,1 g of Span 85® which is heated to 90°C.

The resulting emulsion is cooled to room temperature to form a stable dispersion in water of solid and very hard particles which absorb UV radiation.

The active ingredient to matrix ratio for this formulation is 1/2, and has been varied over the range of 1/20 to 2/1.

EXAMPLE VI 10 g of liquid Escalol 587® is dissolved into 20 g of a commercial paraffin which has been melted at 60°C.

This solution is emulsified for two minutes by means of an ultra-sonic probe into 70 g of a water solution containing 0,1 g of Triton X-100® which is heated to 60°C. The resuling emulsion is cooled to room temperature to form a stable dispersion in water of solid but especially soft particles which absorb UV radiation.

Microscopic examination reveals that the particles are predominantly less than one micron. The active ingredient to matrix ratio for this formulation is 1/2, and has been varied over the range of 1/20 to 5/1.

EXAMPLE VII molecular weight polyethylene which has been melted at 90°C.

The resulting emulsion is cooled to room temperature to form a stable dispersion in water of solid and very hard particles which absorb UV radiation. Microscopic examination reveals that the particles are predominantly less than one micron.

The active ingredient to matrix ratio for this formulation is 1/2, and has been varied over the range of 1/20 to 2/1. EXAMPLE VIII

5 g of Escalol 587® and 5 g of Escalol 567® are dissolved into 20 g of a commercial paraffin which has been melted at 60°C.

This solution is emulsified for two minutes by means of an ultra-sonic probe into 70 g of a water solution containing 0,1 g of Triton X-100® which is heated to 60°C. The resulting emulsion is cooled to room temperature to form a stable dispersion in water of solid but especially soft particles which absorb UV radiation. Microscopic examination reveals that the particles are predominantly less than one micron.

The active ingredient to matrix ratio for this formulation is 1/2, and has been varied over the range of 1/20 to 5/1. EXAMPLE XI

5 g of liquid Escalol 587® and 5 g of Escalol 567® are dissolved into 20 g of a low molecular weight polyethylene which has been melted at 90°C. This solution is emulsified for two minutes by means of an ultra-sonic probe into 70 g of a water solution containing 0,1 g of Span 85® which is heated to 90°C.

EXAMPLE X 5 g of UV-CHEK AM-300® and 2,5 g of Escalol 587® are dissolved into 20 g of a commercial paraffin which has been melted at 60°C.

This solution is emulsified for two minutes by means of an ultra-sonic probe into 70 g of a water solution containing 0,1 g of Triton X-100® which is heated to 60°C.

The resulting emulsion is cooled to room temperature to form a stable dispersion in water of solid but especially soft particles which absorb UV radiation.

The active ingredient to matrix ratio for this formulation is 1/2, and has been varied over the range of 1/20 to 5/1.

EXAMPLE XI 5 g of UV-CHEK AM-300® and 2,5 g of Escalol 587® and 2,5 g of Escalol 567® are dissolved into 20 g of a low molecular weight polyethylene which has been melted at 90°C.

This solution is emulsified for two minutes by means of an ultra-sonic probe into 70 g of a water solution containing 0,1 g of Span 85® which is heated to 90°C. The resulting emulsion is cooled to room temperature to form a stable dispersion in water of solid and very hard particles which absorb UV radiation.

The active ingredient to matrix ratio for this formulation is 1/2, and has been varied over the range of

Claims

1. A water based dispersion constituted by colloidally stable submicron particles of an active ingredient encapsulated into a protective matrix and dispersed in water, wherein said active ingredient is an UV absorbing organic molecule.

2. Water based dispersion according to claim 1, wherein the active ingredient is 2-Hydroxy-4-n- Octyloxybenzophenone (UV-Chek AM-300┬«⁾ .

3. Water based dispersion according to claim 1, wherein the active ingredient is Octyl-Salicylate (Escalol

587┬«) .

4. Water based dispersion according to claim 1, wherein the active ingredient is 2-Hydroxy-p- methoxybenzophenone (Escalol 567┬«).

5. Water based dispersion according to claim 1, wherein said protective matrix is either made of commercial paraffin, or bees wax, or low molecular weight polyethylene .

6. Water based dispersion according to anyone of the preceding claims, wherein the submicron particles have a diameter comprised in the range from 0,05 microns to 5,0 microns.

7. Water based dispersion according to anyone of the preceding claims, wherein the the UV absorber to encapsulating matrix ratio range is 1/20 to 10/1.

8. Method for obtaining a water based dispersion of solid particles containing UV absorbing components as active ingredients comprising the following steps: a) heating an encapsulating matrix above its melting point; b) dissolving an UV absorbing material in the melted encapsulating matrix; c) heating water to the same temperature as the encapsulating matrix; d) adding a suitable surfactant in a predetermined quantity to the heated water; e) emulsifying the heated solution comprising the UV absorbing material; f) cooling down the emulsified mixture in order to obtain the formation of an uniform mixture of solid particles containing said UV absorbing components .

9. Method according to claim 8, wherein the encapsulating matrix is either made of commercial paraffin, or bees wax, or low molecular weight polyethylene .

10. Method according to claim 8, wherein said UV absorbing component is either constituted by 2-

Hydroxy-4-n-Octyloxybenzophenone (UV-Chek AM-300┬«) , or 2-Hydroxy-p-methoxybenzophenone (Escalol 567┬«), or Octyl-Salicylate (Escalol 587┬«) .

11. Method according to claim 8, wherein said surfactant is either constituted by Sorbitan monooleate (Span

80┬«) , or Octylphenooxypolyethoxyethanol (Triton X- 100┬«) or Sorbitan trioleate (Span 85┬«) .

12. Method according to claim 8, wherein the emulsifying operation is carried out by means of either an ultra- sonic probe or a Mantin Gaulin Homogenizer.

13. A gravure ink including in its formulation a water based dispersion constituted by colloidally stable submicron particles of an active ingredient encapsulated into a protective matrix dispersed in water, wherein said active ingredient is an UV absorbing organic molecule.

14. A gravure ink which does not contain pigment with the addition of a water based dispersion constituted by colloidally stable submicron particles of an active ingredient encapsulated into a protective matrix dispersed in water, wherein said active ingredient is an UV absorbing organic molecule.

15. A coating incorporating a water based dispersion constituted by colloidally stable submicron particles of an active ingredient encapsulated into a protective matrix dispersed in water, wherein said active ingredient is an UV absorbing organic molecule .