MXPA98008817A - Granula composition preparation - Google Patents

Abstract

A product is provided in agglomerated particles comprising zinc oxide, boric acid and at least 3 weight percent of 3ZnO.5B203.14H20, based on the total weight of zinc oxide, boric acid and 3Zn0.5B203.14H20. This product can be used as a frit for the production of ceramics

Description

"PREPARATION OF GRANULAR COMPOSITIONS" This invention relates to an agglomerated particulate product comprising zinc oxide and boric acid (H3BO3), with a process for the preparation thereof and with a frit comprising said product. The ceramic industry uses a mixture of silicon dioxide powder and other compounds such as zinc oxide and boric acid powders as a frit. These particulate components are typically mixed together, optionally with other ingredients such as colorants, and the composition is melted and applied to a product before baking. Processes for making particulate materials, such as spray drying, often yield products in the form of small particles. These products are often difficult to handle and typically are powdery and low density. A specific problem has arisen with respect to zinc oxide dust. This powder has poor fluidity. We have surprisingly discovered a process by which a composition comprising zinc oxide and boric acid can be produced in a form having good fluidity, and which is suitable for use to form a frit. The applicant has found that it is not possible - - carry out a simple agglomeration technique, using an intimate mixture of zinc oxide and boric acid. Carrying out the normal agglomeration technique in this mixture, followed immediately by the usual drying methods, leads to agglutination after being allowed to stand for short periods of high humidity. The resulting product can not be used in the manufacture of frits. The applicant has now discovered that the process can be modified in an unexpected manner to ensure that this agglutination does not occur. This modification involves allowing the components to undergo a controlled reaction after agglomeration, but before the product dries. The product of the present invention mixes well with other frit components and can lead to chips of improved quality, improved batch consistency, and consequently better glaze. According to one aspect, the present invention provides an agglomerated particulate product comprising zinc oxide, boric acid and at least 3 percent by weight of 3ZnO.5B2O3.14H20, based on the weight of zinc oxide, Boric acid and 3Zn0.5B2O3.14H20. The present invention also provides a process for preparing an agglomerated particulate product comprising: (i) agglomerating an intimate mixture of zinc oxide particles and boric acid particles with up to 20 weight percent water, based on the total weight of the particles, in the form of a fine spray or steam; (ii) stir agglomerated particles; and (iii) drying the agglomerated particles; wherein the temperature of the mixture during steps (i) and (ii) is at most 50 ° C and the temperature of the mixture during at least part of step (i) and / or step (ii) is by at least 35 ° C, and the agglomerated product is able to be obtained in this way. According to another aspect, the invention provides an agglomerated particulate product comprising: (i) agglomerating an intimate mixture of zinc oxide particles and boric acid particles with up to 20 weight percent water, based on the total weight of the particles, in the form of a fine spray or steam; (ii) stir agglomerated particles; and (iii) drying the agglomerated particles; wherein the temperature of the mixture during step (i) and (ii) is at most 50 ° C, and the temperature of the mixture during at least part of step (i) and / or step (ii) is at least 35 ° C.

The present invention also provides a frit comprising an agglomerated particulate product as defined above. In the process of the present invention, a reaction is carried out at the points of contact between the zinc oxide particles and the boric acid particles. The zinc oxide and the boric acid react to form 3ZnO.5B2O3.14H2O. The initial particles of zinc oxide and boric acid can be any size. The zinc oxide particles can be significantly smaller than the boric acid particles. Commercially available zinc oxide particles are used appropriately. For example, the zinc oxide particles may have a D50 size (ie, 50 weight percent less and 50 weight percent more) of 1 to 5 microns. Commercially available boric acid particles can be used, but preferably ground boric acid is used. The commercially available boric acid can be used to obtain a stable product, visually similar to that which uses the boric acid ground. However, using ground boric acid, the conditioning time (ie, step ii) is reduced, ie, there is a faster formation of 3Zn0.5B2O3.14H20, there is generally less product of accessible size, ie, - > 500 micrometers, and the segregation index of the final product is lower, that is, the tendency for the particles to segregate according to the size is reduced. Preferably, the D50 size of initial boric acid is reduced to 100 microns to 200 microns. The quality of ZnO "White Seal" (trademark) is used by approximately 60 percent of the frit makers, and can be used in this invention as the initial zinc oxide. Other grades of ZnO can also be used, for example, ceramic quality. The zinc oxide and the boric acid can be present in any proportion. The relative proportions used will depend on the relative proportions desired in the final frit. Preferably, however, zinc oxide and boric acid are present in a weight ratio of 2: 1 to 4: 1, especially of about 3: 1 (which is determined as ZnO: B2? 3). 3ZnO.5B2O3.14H20 is present in an amount of at least 3 weight percent, preferably at least 5 weight percent and up to 20 weight percent, more preferably about 5 weight percent a 20 percent by weight (eg from 5 to 10) based on the total weight of zinc oxide, boric acid and the - 3ZnO.5B2O3.1 H20 in the agglomerated particulate product. There is no additional advantage in that the present compound or mixture is much greater than 5 weight percent. If the 3Zn0.5B2O3.14H20 is present in an amount of less than 3 weight percent, the product is stable, that is, when it is subjected to 100 percent relative humidity for a week it does not show signs of agglutination, ie , it still flows freely. The particle size of the agglomerated particles is such that the agglomerated particles have good fluidity. Typically, the particle size is from 1 micrometer to 500 micrometers. Desirably, the composition does not contain particles having a particle size of less than 10 microns, preferably less than 25 microns. A preferred particle size is 25 microns to 500 microns. The size D50 of the agglomerated particles is preferably 80 micrometers to 130 micrometers, more preferably about 110 micrometers. If the composition produced contains particles that have a size that is too small or too large, these particles, if desired, can be removed by simple sieving. Any product of excessive size can be sprayed and added back to the composition. Any size product - Less than normal can be recycled or dissolved in the water used to agglomerate the particles. The product of the present invention usually consists of only zinc oxide and boric acid and the reaction product thereof. However, other components may be added before, during or after agglomeration, for example, coloring materials, anticaking agents or other component (s) of the frits. In the process of the present invention, a mixture of zinc oxide particles and boric acid particles is initially prepared. The mixture must be intimate since otherwise the zinc oxide agglomerates by itself and does not cover the desired reaction to the extent necessary. After the formation of the intimate mixture, the agglomeration is carried out in a normal manner by adding water in the form of a fine spray or steam. The techniques for agglomerating small particles to provide products of larger particle size are well known. A comprehensive review for the agglomeration and which can be used in the process of the present invention is provided in the Kirk-Othmer Chemical Technology Encyclopedia, Third Edition (21), pages 77-105.

The agglomeration can be carried out in any suitable apparatus for the mixing of dry particulate materials adapted so that the liquid granulating agent can be sprayed on or otherwise added to the particles. A conventional granulation equipment can be used. An intense mixer such as an Eirich or Lódige mixer can be used, for example. A Winkworth jacketed mixer can also be used. By appropriately adjusting the variables of the process, such as the proportion and amount of water added, the speed of rotation of the mixer, the residence time of the product inside the reactor and the placement of the spray to achieve maximum contact of the water with the particles of the feed material to be granulated, an agglomerated product containing a high proportion of the agglomerates of the desired particle size can be obtained. Particles of smaller than normal and / or excessive size can be removed, for example, by sieving, if a critical particle size distribution is desired for the agglomerated product. The time required for the desired degree of agglomeration depends on the amount of water added and the rate of agitation. An appropriate agglomeration time is approximately 10 minutes. The particle size of the agglomerated particle product depends on the amount of water - added, the rate of addition and the speed of agitation. A person skilled in the art will be able to easily determine the appropriate agglomeration conditions. In view of the requirement that there be a separate stirring step after the particles have agglomerated, an intermittent operation can be used even though it is possible to carry out the process of the present invention in a continuous operation. Water for agglomeration is used in an amount of up to 20 weight percent based on the total weight of the particles. Desirably, the water is used in an amount of 8 percent to 15 percent by weight, preferably 8 percent to 12 percent by weight, and especially preferably about 10 percent by weight. If used in the form of a fine spray, the water desirably has a temperature of 15 ° C to 25 ° C. Preferably, the water is atomized, for example having a droplet size of about 100 microns. If desired, it may contain dissolved or suspended components, for example, zinc oxide, boric acid, a dye, an anti-agglutination agent or other component (s) used in the frit. The granulated product is then stirred in the second step. The product may be stirred in the reactor used for agglomeration or may be discharged into another vessel provided with agitation means, such as a stirrer, for example, a paddle-Z / ribbon mixer or a rotary drum mixer. Agitation is carried out for a sufficient period of time to ensure that at least 3 weight percent, preferably at least 5 weight percent of 3ZnO.5B2O3.14H20, has been formed. The stirring can be carried out for example for from half to two hours (e.g. from 1 to 2 hours), preferably from 45 minutes to 1 hour. Even when agitation can be carried out for a longer period, there is no advantage in this. If agitation is carried out in the granulation vessel, the vessel should be provided with a variable speed agitator. For example, the mixture can be stirred at high speed for agglomeration but stirred at a lower speed, for example, 200 revolutions per minute, during the stirring step. It is necessary that an appropriate agitation speed be used to ensure that the particles stay moving but do not disintegrate. The scale can be from 100 to 300 revolutions per minute. However, appropriately, the scale is from 5 to 50 revolutions per minute, preferably from 10 to 30 revolutions per minute, and more preferably from approximately 10 revolutions per minute.

It is essential that the temperature of the mixture of zinc oxide and boric acid reaches at least 35 ° C for at least part of the weight (i) and / or (ii) in order to form 3ZnO.5B2O3.14H20. The temperature, however, should not exceed 50 ° C and should generally be at most 42 ° C, preferably at a high of 40 ° C, in order to avoid dehydration of the components. The temperature can be raised during the agglomeration step (i) by, for example, external heating or by stirring. The high speed agitation will raise the temperature of the mixture. The temperature can be maintained at 35 ° C or higher during all or only part of the granulation step. For example, the granulation can be started at room temperature (20 ° C) and stopped once the desired temperature has been reached, for example at 35 ° C, after all the water has been added. The temperature of the agglomerated product during the stirring step (ii) can also be at least 35 ° C. The temperature can be maintained at 35 ° C or more during all or part of the agglomeration step. If the temperature of the agglomerated product is at least 35 ° C at the end of the agglomeration step, the agglomerated product can simply be allowed to cool in the stirring step. In order to avoid the disintegration of agglomerated particles, high speed agitation can not be used during the stirring step. Therefore, if it is desired to increase the temperature or maintain an increased temperature during the stirring step, it is necessary to provide an external heat source. After the stirring step, the agglomerated particulate product is dried. An appropriate drying temperature is 60 ° C to 80 ° C (product temperature). The drying can be carried out for example, for about 10 minutes. Even when boric acid begins to lose water to form metaboric acid at a temperature of more than 60 ° C, decomposition is prevented due to the short duration of the drying step. The object of the drying step is to remove all the water besides the water of crystallization that is present in the agglomerated particle product. In order to obtain a temperature of 60 ° C to 80 ° C for the material, a dryer can be used, for example, having an inlet temperature of 110 ° C and an outlet temperature of 80 ° C. Any dryer such as a fluid bed, rotary tray or vibratory dryer may be used. The agglomerated particulate product can optionally be cooled to less than 25 ° C before the drying step. Generally speaking, if the drying step is to be used in intermittent drying, there is no need for cooling before drying. On the other hand, if a continuous dryer is to be used, it is generally preferred that the agglomerated product be cooled first. The object of cooling is to decelerate or stop the further formation of 3ZnO.5B2O3.14H20, which can lead to agglutination of the wet product. The present invention is further described with reference to the accompanying drawing, which schematically shows a plant for the production of the agglomerated particulate product according to the present invention. Referring to the drawing, the plant comprises a source of boric acid 1, a mill 2 and a reservoir for holding the ground boric acid 3 together with a reservoir for retaining the particulate zinc oxide 4. The weighing belts 5 and 6 respectively move the material from the tanks 3 and 4 to the agglomerator / conditioner 7, appropriately in a Winkworth jacketed mixer. A pipe 8 is provided for the introduction of water into the agglomerator / conditioner 7. Also, the agglomerator / conditioner 7 is provided with an external heater 9. A line 10 from the agglomerator / conditioner 7 communicates with a mixer / cooler 11 that is provided with a cooler 12.

The product of the mixer / cooler 11 passes to a wet tank 13, via a screw feeder 14, to a continuous dryer which is suitably a vibrating fluid bed dryer. The water is discharged from the dryer at 16 and the fines are removed along the line 17. The product from the dryer passes along the line 18 to a screen 19 and subsequently to the intermittent tanks 20 for dispatch. The line 17 from the dryer 15 is provided with a cyclone 21 whereby any material containing no fines can be returned along line 22 to line 18 and the undersized material along the line 23 through the powder socks 24 into the receptacle. The additional oversize material of the screen 19 can pass along the line 26 to the receptacle 25. The receptacle 25 is connected through a mill 27 and the line 28 with a hopper 29 from where the material can be introduced into the agglomerator / Conditioner 7. During use, the boric acid from source 1 is ground in mill 2 to the required particle size and passed to tank 3 from where it is introduced, through weight belt 5 towards the agglomerator / conditioner 7, and the zinc oxide from the deposit 4 se - introduced along line 6 and the ground and recycled material can be introduced from hopper 29. An intimate mixture of the ingredients of boric acid and zinc oxide is formed in the agglomerator / conditioner 7 and then the water from the line 8 is sprayed to the agglomerator / conditioner 7. Once the agglomeration step has been completed, the agitation rate in the agglomerator / conditioner 7 is reduced and the agglomerated product is conditioned, with stirring, with the reaction of the zinc oxide. and boric acid. Supplemental heating may be provided as required by use of the heater 9. Preferably stirring is carried out over a period of 45 minutes to one hour, at a stirring speed of 10 to 30 revolutions per minute, more preferably , of approximately JLO revolutions per minute and under temperature conditions similar to those in the agglomeration step. The conditioned agglomerator / conditioner product 7 is passed along the line 10 to the mixer / cooler 11 provided with a cooler 12. In the mixer / cooler-11, the product is stirred slowly to prevent agglomeration and is cooled e.g. until less - of 25 ° C with the aim of preventing or suppressing an additional reaction. The cooled product of the mixer / cooler 11 passes through the wet tank 13 and the screw feeder 14 to the dryer 15, where the maximum temperature of the product is generally in the order of 70 ° C. The dried product is removed from the bottom of the dryer 15 through line 18 to a screen 19, from which the agglomerated particulate product of the required size is passed to intermittent tanks 20 for subsequent dispatch. The water is removed from the dryer 15 in 16 and the fines removed along the line 17 are separated in the cyclone 21 and the undersized material passes along the line 23 through the socks 24 of powder to the receptacle 25. Any retained material that does not contain fines from the cyclone 21 is recycled along the line 21 to line 18 from there to the sieve 19. The oversize material from the sieve 19 is recycled along the line 26 to the receptacle 25. The material of the receptacle 25 is milled in the mill 27 and passed along the line 28 to the hopper 29 from where it is recited towards the agglomerator / conditioner 7.

- The agglomerated particles can be used in a frit. A frit is made by mixing the different compounds to obtain a composition that provides the desired glazing properties. Thus, for example, for fast baked tiles the frit typically has the following composition (which is expressed as oxides even when the components are not necessarily present in the form of oxide): Sio2 from 50 to 60% by weight AI2O3 of 4 to 7% by weight B2O3 (as H3BO3) from 3 to 6% by weight CaO from 8 to 10% by weight MgO from 1 to 3% by weight Na2? from 0 to 1% by weight K20 from 2 to 4% by weight ZnO from 8 to 10% by weight BaO from 0 to 2% by weight The raw materials of the frit can be minerals or raw products, such as quartz, feldspar (Na or K), carbonates (Ca or Mg), zinc oxide, alumina, kaolins, zirconium silicates and borates in the form of boric acid, colemanite, ulexite or sodium tetraborate. The agglomerated particulate product of the present invention desirably has a weight ratio of Zn: H3B? 3 (which is determined as ZnO: B2? 3) to that which is used in the frit. If the product does not have the desired ratio, the product can be added to the remaining constituents of the frit in order to provide the required amount of ZnO and then additional borate can be added, for example, in the form of boric acid to reach the required amount of B2O3. The frit melts and cools quickly and then is used in the usual way. The invention is further illustrated in the following examples.

EXAMPLES Example 1 1,488 grams of granular technical grade boric acid having a maximum particle size of less than 1 millimeter and a D50 of 250 microns, and 2,512 grams of "White Seal" grade zinc oxide having a maximum particle size of less than 5 micrometers were intimately mixed for one minute in an Eirich mixer of 8 liters working volume at 950 revolutions per minute. The stirring rate was increased to 1900 revolutions per minute, and 424 grams of water were added - in the form of a spraying through 6 to 7 minutes (about 65 grams per minute). The agglomerated product thus obtained was then transferred to a stirred rotating drum at 200 revolutions per minute and allowed to cool through a 120 minute period The product was then dried in a fluid bed drier at 80 ° C for 10 minutes and subsequently screened to remove particles having a size of more than 1200 microns.The results are shown in Table 1.

Example 2 Example 1 was repeated except for the following changes: • 330 grams of water were added during the agglomeration step; • low speed agitation (800 revolutions per minute) was used during the agglomeration step; • the temperature of the mixture during the agglomeration was maintained at 35 ° C throughout the agglomeration step by heating. The results are shown in Table 1.

Example 3 - Example 1 was repeated except for the following changes: • 440 grams of water were added during the agglomeration step; • agitation was used at low speed (800 revolutions per minute) during the agglomeration step; • the temperature of the mixture during the agglomeration was maintained at 35 ° * C throughout the agglomeration step by heating; • the temperature of the mixture during stirring was maintained at 35 ° C throughout the stirring step by heating. The results are shown in Table 1.

Comparison Example 1 Example 1 was repeated except for the following changes: • 440 grams of water were added during the agglomeration step; • Agitation at low speed (800 revolutions per minute) was used during the agglomeration step in such a way that the temperature of the mixture through the agglomeration step was from 20 ° C to 21 ° C. The results are shown in Table 1.

- - EXAMPLE 4 50 kilograms of ground boric acid having a maximum particle size of < 600 micrometers and a D50 of 76 micrometers, and 85 kilograms of White Seal-grade zinc oxide having a maximum particle size of < 5 micrometers plus 13 kilograms of recycled product (maximum particle size 500 micrometers) at 30 revolutions per minute in a Winkworth mixer that has a work volume of approximately 200 liters (actual volume, 322 liters). The agitation rate was increased to 80 revolutions per minute and 20 kilograms of water were added in the form of a spraying over a period of 10 minutes (2 kilograms per minute). Agitation at 80 revolutions per minute was continued for an additional 5 minutes and then intermittently for 30 seconds every 5 m minutes over a period of 40 minutes. The stirring rate was reduced to 30 revolutions per minute and a sufficient amount of solid carbon dioxide was added after an additional 10 minutes. The temperature of the product was < 25 ° C. The product was discharged from the mixer through a coarse screen (5 millimeters) into a storage hopper before being dried in a continuous dryer. The conditions in the dryer were such that the inlet temperature was 140 ° C to 156 ° C; the air outlet temperature was 48 ° C to 56 ° C, and the product temperature was < 70 ° C. The product was sieved, to remove particles that had a particle size of > 500 micrometers. The results are shown in Table 1. TABLE 1 Example Example Example 1 2 3 H3BO3 used 1488 g 1488 g 1488 g Used ZnO 2512 g 2512 g 2512 g water added 424 g 330 g 440 g conditions of 1900 rpm without 800 rpm temp. 800 rpm temp. agglomeration heating warming heating - temp 20-35 ° C 35 ° C 35 ° C low speed conditions low speed low speed agitation without heating without heating temp. of heat-temp. 35-20 ° C temp. 35-20 ° C 35 ° C product with size 3.2 3.6 of > 1200μm before being sieved (% by weight) product with size 1.7 20.5 29.9 of < 75μm (% by weight) D50 product after 317 237 247 sieving (μm) volumetric density 1,180 1,328 emptied (kg / mc Hausner ratio 1,122 1,226 (measure in accordance with ISO 787/11) flow regime 129 medium (ml / s) content of 3Zn0.5B203.14H20 agglutination after No No Not a week at relative humidity of 100% - - TABLE 1 (Continued) Example Example 1 Comparison 4 H3BO3 used 1488 g 50 kg Used ZnO 2512 g 85 kg * water added 440 g 20 kg conditions of 800 rpm without 80 without agglomeration heating heating temp 20-21 ° C temp. 25-28 ° C low speed conditions 80 rpm stirring without heating without heating temp. 22-20 ° C temp. 28-40 ° C product with size 2.0 of > 1200μm before being sieved (% by weight) product with size 15.1 40.0 of < 75μm (% by weight) - - D50 product after 208 100 sieving (μm) volumetric density 1,517 emptied (kg / m3) Hausner ratio 1,201 (measure in accordance with ISO 787/11) flow rate 17 medium (ml / s) content of 2 3 3Zn0. 5B203. 14H20 Agglutination after Yes No one week at 100% relative humidity * plus 13 kilograms of recycled material The medium flow rate is determined by allowing a known volume of powder to flow through a calibrated orifice and recording the flow time using the following apparatus and procedure: APPARATUS 1. Plastic funnel. 2. Glass tube - 50 centimeters in length and 3.5 centimeters in internal diameter. The tube is calibrated using water to provide upper and lower marks so that the volume between the marks is 287 milliliters. 3. Brass hole with diameter of 2.25 centimeters. 4. Metal sliding clamp to block the bottom of the tube while it is filled with dust. 5. Chronometer calibrated in tens of a second. PROCEDURE 1. Fit the 2.25 cm diameter hole in the tube. 2. Close the hole with the metal slide and fill the tube with the powder that is being tested, using the funnel. 3. Open the hole. 4. Run the stopwatch when the dust passes through the top mark. 5. Stop the timer when the dust passes through the lower graduation mark. 6. Observe the elapsed time. 7. Hold the powder and repeat 2 to 6 twice more. CALCULATIONS The average flow rate is calculated from the volume between the two marks and the time is given in milliliters per second.

Claims (15)

- - R E I V I N D I C A C I O N E S:

1. An agglomerated particulate product comprising zinc oxide, boric acid, and at least 3 weight percent of 3ZnO.5B2O3.14H20, based on the total weight of zinc acid, boric acid and 3Zn0.5B2O3.14H20.

2. A product according to claim 1, comprising from 5 percent to 20 weight percent of 3ZnO.5B2O3.14H20.

3. A product according to claim 1 or 2, wherein the zinc oxide and the boric acid are present in a weight ratio of 2: 1 to 4: 1 (which is determined as ZnO: B2? 3).

4. A product according to claim 3, wherein the zinc oxide and the boric acid are present in a weight ratio of about 3: 1.

5. A product according to any of the preceding claims, wherein the particle size of the agglomerate is from 1 micrometer to 500 micrometers.

6. A product according to claim 5, wherein the particle size of the agglomerate is from 25 microns to 500 microns.

7. A process for preparing an agglomerated particulate product comprising: (i) agglomerating an intimate mixture of zinc oxide particles and boric acid particles with up to 20 weight percent water, based on the total weight of the particles, in the form of a fine spray or steam; (ii) stir agglomerated particles; and (iii) drying the agglomerated particles; wherein the temperature of the mixture during steps (i) and (ii) at most is 50 ° C and the temperature of the mixture during at least part of step (i) and / or step (ii) so less than 35 ° C.

8. A process according to claim 7, wherein from 10 percent to 15 percent by weight of water is used in the form of a fine spray having a temperature of 15 ° C to 2-5 ° C. A process according to claim 7 or 8, wherein the temperature of the mixture during steps (i) and (ii) does not exceed 42 ° C. 10. A process according to claim 7, 8 or 9, wherein the agglomerated particles that have been stirred * in step (ii) are cooled to less than 25 ° C before being dried in step (iii). 11. A process according to any of claims 7 to 10, wherein the particles are dried at a temperature of 60 ° C to 80 ° C for 10 to 20 minutes. 12. An agglomerated particulate product obtainable by the process comprising: (i) agglomerating an intimate mixture of zinc oxide particles and boric acid particles with up to 20 weight percent water, based on the total weight of the particles. particles in the form of a fine spray or vapor; (ii) stir agglomerated particles; and (iii) drying the agglomerated particles; wherein the temperature of the mixture during step (i) and step (ii) is at most 50 ° C and the temperature of the mixture during at least part of step (i) and / or step (ii) ) is at least 35 ° C. 13. A product according to claim 12, wherein from 10 percent to 15 percent of water is used in the form of a thin roll having a temperature of 15 ° C to 25 ° C. 14. A product according to claim 12 or 13, wherein the particles are dried at a temperature of 60 ° C to 80 ° C for 10 to 20 minutes. 15. A frit comprising a product as defined in any of claims 1 to 6, and 12 to 14.