NZ601006B - Use of hydrophilic organomodified siloxanes as a processing aid for melt granulation - Google Patents

Abstract

Patent 601006 Disclosed is the use of an organomodified polysiloxane of formula (I) as a release agent in melt granulation. The polysiloxane of formula (I) is a polyether polysiloxane, having repeating alkoxy units of ethoxyl followed by propoxyl and optionally additionally butoxyl or styrene units to comprise the grafted chains at R1, R2 and R3 positions. ne units to comprise the grafted chains at R1, R2 and R3 positions.

Description

PATENTS FORM NO. 5 Our ref: JB 233940NZPR NEW ZEALAND PATENTS ACT 1953 COMPLETE ICATION Use of hydrophilic organomodified siloxanes as a processing aid for melt granulation We, Evonik Goldschmidt GmbH, a German company of Goldschmidtstrasse 100, 45127, Essen, Germany hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly bed in and by the following statement: — 1 - (followed by page 1a) Use of hydrophilic modified siloxanes as a processing aid for melt granulation The present invention is directed to the use of organomodified polysiloxanes which have at least three ent polyether radicals, at least two of these polyether radicals differing by at least 9% by mass in the proportion of ethylene oxide units therein in the total weight of the polyether radical, as a e agent or release agent constituent in a s for melt granulation.

Melts are obtained in many industrial chemical processes. For example, large amounts of liquid sulphur arise from what is called the Clauss process in refineries. Various operations are now available for converting the liquid melt to a manageable and solid form. The molten products are converted with an application device to suitable forms such as balls, flakes, pellets or other forms, preferably homogeneous forms, preferably homogeneous, veiy substantially spherical forms 1O (cooling belt plants). in the frequently continuous processes, the industry pays special attention to iness of the conveying s, which are preferably steel conveyor belts, and good separation of the shaped bodies from the conveying devices, in order that the process can run uously for prolonged periods. In addition, good meterability of the products and inexpensive and clean packaging of the products are required. More ularly, a homogeneous shape and size of the shaped bodies is important, this requiring good separation of the products from the conveyor belts, in order that these products can be transported further and are meterable accurately at a later stage. if the shape of the melt granules has comers and edges, these can fracture and cause dusts as a result, especially in the course of sulphur pelletization. in addition, such bodies are unwanted since they cannot be metered tely in downstream operations.

Steel belt s are a frequently used technology in this solidification of the melts. In the course of this, the melt is continuously cooled and solidified. By means of different technologies, it is possible to form a wide variety of different shapes of particular size. Perforated plates are a relatively old technology (cf. Aufbereitungstechnik 1970 No. 5, p. 278). These involve conducting a sulphur melt from the Clauss process through one or more perforated plates into a piilling vessel filled with water (US-A 3 637 361).

DE—A 2928401 describes a process for pelletizing sulphur, in which molten r is applied to a metal canier and cooled until fication, the application of the molten sulphur to the metal carrier being preceded by application of a composition comprising t, organic te and carboxy-functional siloxanes. la (followed by page 2) A technology which is widespread nowadays is the fication of sulphur melts by means of steel belt coolers and the “Rotofonner®’ (Rotoforrn system), as supplied, for example, by Sandvik Process Systems. This involves supplying the molten sulphur at a temperature of 125°C to 145°C to a Rotoformer®, and the latter applies it in droplet form neously to a steel belt, the underside of which is cooled by water, for example by means of spray nozzles, or it is passed through a water bath. In this operation too, a good separation of the shaped bodies and homogeneous, very substantially spherical shape of the melt es is ensured. The principle of these processes is described, for e, in US 6398989 and US 4279579, and in the brochures “Sandvik — lhr Partner in der Schmelzengranulierung”, PS—442/GER 10.2003 and “Sandvik s Systems — lhr Partner in industriellerVerfahrenstechnik”, PS-400 GER 2.2011, each published by the Sandvik group (wwwsmtsandvikcom).

Especially in the granulation of sulphur by the various processes for producing particular melt granules, for example pellets, it is necessary to use release agents to prevent possible adhesion to steel belts or other conveying devices. In addition, the release agents have a positive influence on the shape of the melt granules, which improves subsequent packaging and reuse (accurate meten’ng). One example of a frequently used release agent is silicone oil. GB 1 537 888 describes the use of silicone oils of viscosity 20 — 50 cSt from, for e, Dow Coming. This fluid is sold under the DOW CORNlNG® 200 FLUID, 20 cSt trade name. The release agent is dispersed in the molten sulphur and simplifies pelletization, which is effected on a cooled steel belt. One disadvantage of this technology is that it is necessary to disperse the silicone oil in the r for this purpose. Since the silicone oil is a liquid completely incompatible with water, which is used to cool and clean the steel belts, there are instances of soiling and greasy residues in the plant, which ely affect the separation of the shaped bodies from the steel belt cooler.

An improvement was achieved by the use of silicone oil emulsions. The application of the emulsion by spraying or else dipping of the steel belts eases the process, but silicone residues ng on the belts cannot be reemulsified and therefore also lead to soiling. A r disadvantage of the emulsions is the ity thereof. Separation of the silicone oil from the aqueous phase frequently occurs even at 35°C, which complicates the use thereof in refinen'es in hot countries, since the silicone oil frequently separates even in e or reservoir s, or in conveying devices.

The disadvantage of the products used to date has been reduced by the use of hydrophilic, cally modified siloxanes. A product frequently used, for e by Sandvik among others, is en® 5863, sold by Evonik Goldschmidt GmbH. The latter is water-soluble, and modified on the siloxane chain with two polyethers of ent molar mass, both of which have the same content by mass of ethylene oxide, of about 40% ethylene oxide and about 60% propylene oxide. The product is applied in aqueous solution; the disadvantages of emulsion stability at relatively high temperature are eliminated. However, one disadvantage of this t class is that the good separation of the melt granules does not remain constant, and it instead becomes somewhat more difficult as a function of time.

In addition, the shape of the melt granules can deviate slightly from the optimal spherical form.

Bulging melt es are obtained, among which flatter shaped bodies cause the described problems of the thinner edges breaking off and metering problems.

The solidified r is frequently moved between production and reuse (transport, storage, handling, etc), and so preference is given to low evolution of dust and low propensity to fracture. it was therefore an object of the present invention to provide release agents for use in a process for ing sulphur particles, which avoid one or more of the disadvantages of the prior art.

More particularly, it was an object of the present invention to provide a separating component of very good water solubility, which ensures very good permanent separation of the sulphur granules and, even in the long term, does not give residues on the steel belt which adversely affect the tion or the process running. The melt granules should preferably give homogeneous, very substantially spherical shapes which thus do not have any fragile edges. it has been found that, singly, organomodified loxanes as defined herein achieve this object, or at least provide the public with a useful altemative. The organomodified polysiloxanes are adsorbed onto the sulphur granules and thus ensure a very good separation of the melt granules.

The inventive use has the advantage that no residues whatsoever remain on the steel belt. The invention also has the age that the melt es have a homogeneous spherical shape or at least rger” shape, and thus do not have any edges or flat, fragile regions which can 3O fracture in the course of further processing/packaging. Dusts and irregularly shaped bodies are thus avoided, and a cleaner sing operation and more accurate metering of the melt granules are enabled.

A further advantage of the present invention is that the water solubility of the organomodified polysiloxanes considerably simplifies the use and ng of the granulation apparatus. The water solubility also achieves the effect that the release agent can be applied to the steel belt in virtually any thickness, by varying the concentration of the organomodified polysiloxane in the aqueous solution and the amount of the solution applied to the steel belt as a release agent.

The subject-matter of the invention is described by way of example after, without any intention that the invention be restricted to these illustrated embodiments. When ranges, general formulae or compound classes are specified hereinafter, these shall include not only the corresponding ranges or groups of compounds which are mentioned explicitly, but also all sub- ranges and sub-groups of compounds which can be obtained by selecting individual values (ranges) or compounds. When documents are cited in the context of the present ption, the content thereof, especially in relation to the matter in whose context the nt has been cited, shall form a full part of the disclosure-content of the present invention. it chemical 1O (empirical) formulae are used in the present ion, the indices specified may be either absolute numbers or averages. In polymeric compounds, the indices are preferably es. tages are, unless stated otherwise, figures in percent by weight. If measurements are reported after, these measurements, unless stated otherwise, have been performed under standard conditions (25°C and 1013 mbar). lf averages are reported after, these are weight averages, unless stated othenrvise.

The terms “melt e,H (Igranule” and “pellet” are understood in the context of the present invention to be synonymous terms. “Bn'quettes” shall also be understood in the context of the present invention to be granules or granular maten'als. The terms “melt granulation” and “melt pelletization” shall be covered hereinafter in the context of the present invention by the collective term “melt granulation”.

The inventive use features use of organomodified polysiloxanes of the formula (l) tlillf lit llf li‘ R4-—Si-O Si-O Si O Si O Si-O Si—R4 t it in Lila tits if: where N = a + b + c + d + 2 = 20 to 210, ably 30 to 100, ally 40 - 60, a = 15 to 205, preferably 35 to 45, b = 1 to 12, preferably 1 to 8, especially 2 to 6, c = 1 to 12, preferably 1 to 8, especially 2 to 6, d = 1 to 12, preferably 1 to 8, especially 2 to 6, the R radicals are each independently identical or different, aliphatic or aromatic arbyl radicals having 1 to 10 carbon atoms, preferably methyl radicals, the R4 ls are each independently identical or different R, R1, R2 or R3 radicals, the R1, R2 and R3 radicals are each independently different polyether radicals of the general formula (ll) 4cm} / o—chs—~\;—:/o~c4Hs \, /OCH20H1;—0R5 \ (dam?! /e \ /f K /g \ ’h \ /1 where e is 3 to 11, preferably 3, f is 6 to 30, preferably 10 to 30, g is 0 to 15, preferably 0 to 10, h is 0 to 5, preferably 0, i is 0 to 5, preferably 0, R5 are independently the same or different and are each a methyl, acetyl or hydrogen radical, ably a hydrogen or methyl radical, more preferably a hydrogen radical, ably with the provisos that the lar weight of the polyether radical of the formula (H) is greater than 200 g/mol, preferably from greater than 400 to 2000 g/mol, and the proportion of ethylene oxide is greater than 45% by mass in the polyether, and at least two of these polyether radicals differ by at least 9% by mass in the proportion of ne oxide units therein in the total weight of the polyether radical, where the percentage by mass of ne oxide in the polyether radical R2 is preferably at least 9% by mass greater than the percentage of ethylene oxide in the polyether radical R1 based in each case on the polyether radicals of the formula (II), where the radicals of the formula (ll) may each be formed randomly, in a gradient or in blocks, as a release agent or release agent constituent in melt granulation.

In formula (ll), the units designated by the index 9 are those which have originated from ene oxide, the units designated by the index h are those which have originated from butylene oxide, and the units designated by the index i are those which have originated from styrene oxide.

The indices a to d and e to i may be natural whole s, or weight averages. The indices are preferably weight averages.

The inventive organomoditied polysiloxanes can be ed, for example, by hydrosilylation from the corresponding unsaturated polyethers and the corresponding SiH-functional siloxanes.

The process used with preference for preparation of the inventive organomodified polysiloxanes is a transition metal-catalysed hydrosilylation of the olefinically unsaturated polyethers with SiH- onal loxanes to form Si-C linkages, as described, for example, in EP 1 520 870, EP 1439200, EP 1544235, US 4,147,847, US 4,025,456, EP 0493836 or US 4,855,379 and the documents cited therein. Preference is given to using a platinum st to catalyse the hydrosilylation.

The unsaturated polyethers used, on which the radicals of the formula (ll) are based, preferably allyl polyethers, can likewise be prepared according to the known prior art. For example, EP 1 360 223 and the documents cited therein describe the preparation of olefinic hers with and without den'vatization of the OH functionality. US 5877268 (and US 5856369) be the preparation of allyl—started polyethers with DMC catalysis. DE 19940797 bes the preparation and use of polyalkylene oxides using ium methoxide as a catalyst. Further 1O processes are described in US 3957843, US 4059605, US 3507923, DE 102005001076 and DE 3121929.

The polyethers are preferably prepared by reacting a starter alcohol, which is preferably allyl alcohol, with ethylene oxide and/or propylene oxide. The polymerization of the alkylene oxides can be performed in pure form or in any desired mixtures. The sequence of the on steps may be as desired, and so it is possible to obtain random, block or gradient rated polyethers according to the procedure.

An organomodified siloxane used in accordance with the invention can be prepared, for example, as follows: a mixture of 28% by weight of SiH—functional polydimethylsiloxane (where N = . 50 and 0.27% by weight of en) is initially charged. To this is added 22.5% by weight of an allyl alcohol-started copolymer containing 48% by weight of ethylene oxide units and 46% by weight of propylene oxide units, prepared according to the prior art by a talysed reaction. in addition, 36% by weight of an allyl alcohol-started copolymer containing 73% by weight of ethylene oxide units and 24% by weight of propylene oxide units is added thereto, and 13.5% by weight of an allyl alcohol—started copolymer containing 91% by weight of ethylene oxide is added thereto. The mixture is heated to 90°C while stin'ing. 5 ppm of um is added in the form of a platinum catalyst. Monitoring of the conversion by determining the SiH value (gas volumetric ination) gives 99.5% SiH conversion after 5 h.

The inventive compounds of the a (i) can be used themselves as release agents, or else as a release agent constituent of a release agent. When the compounds of the formula (l) are used as a release agent constituent, the release agent used is preferably a mixture or solution of the organomodified polysiloxanes of the formula (I) in a solvent. The t may be water or an organic solvent, especially an alcohol, preferably ethanol. Particular preference is given to using the organomodified polysiloxanes of the formula (I) in the form of s solutions. The aqueous solutions used as release agents contain preferably from 0.5 to 50% by weight, more preferably from 1 to 25% by weight and most preferably from 3 to 18% by weight of organomodified polysiloxanes of the formula (I).

The organomodit'red polysiloxanes of the a (I) used preferably have a cloud point from 30 to 70°C, preferably 35°C to 60°C. The cloud point is preferably determined on the basis of DIN EN 1890. Among the ses specified therein, preference is given to using that in which 1 g of sample is analysed with 100 g of water. A on made up in this way is heated in a test tubefbeaker until distinct cloudiness occurs. In the course of cooling under air while ng with the thermometer, the temperature is determined at which the solution is clear or only slightly opalescent.

The possible substances to be used for granulation may, for example, be those on page 18 of the brochure “Sandvik — Ihr Partner in der Schmelzengranulierung”, PS-442/GER 10.2003.

Preferred substances are especially ed from alkane sulphonate, aluminium sulphate, ammonium nitrate, ammonium phosphate, anthracene, antioxidants, antiozonant, asphalt, benzoic acid, bishydroxyethyl terephthalate (BHET), bisphenol A, bitumen, caprolactam, carbazole, crotonic acid, diaminodiphenylmethane (DMA), emulsifiers, emicals, photogelatin, urea, resins, for example acrylic resin, rosin, epoxy resin, hydrocarbon resin, phenol resin, polyamide resin, polyester resin, silicone resin, tall oil resin, calcium stearate, cobalt naphthenate, cobalt stearate, lactam 12, fats, cocoa mass, cheese, chocolate, gelatin, chewing gum base, sauces, soup concentrates, masterbatches, naphthalene, sodium acetate, neopentyl glycol (NPG), paradichlorobenzene, pitch, pesticides, polyethylene glycol, hylene terephthalate (PET), polystyrene, polyvinyl e, powder coatings, PVC additives, PVC stabilizers, cleaning compositions, soap, synthetic, hot melt adhesives, for example based on ethylene-vinyl acetate, polyurethane, ide or polyester, reactive hot melt ves, sulphur, sulphur + bentonite, sorbitol, stabilizers, stearic acid, tants, toluene diisocyanate (TDl), triazole (BTA, TTA), trimellitic anhydride 0'MA), triphenyl phosphate (TPP), subcooling melts, UV stabilizers, waxes, for example paraffin, AKD wax, microwax, PE wax, PP wax, beeswax, filled wax, fragrant wax, wax dyes, montan wax or g wax, washing composition additives, zinc nitrate or zinc te. Very particular preference is given to the inventive use in the case of use of sulphur as the nce to be granulated.

As a result of the preferred use of a release agent/organomodified polysiloxane of the formula (I), the sulphur melting temperature of > 125°C brings about the separation of the organomodified polysiloxanes by vaporization of the water. in the immediate environment of the hot r melt, the organomodifred polysiloxanes precipitate out of the aqueous solution due to the cloud point of ably in the range from 30 to 70°C and are adsorbed on the es of the sulphur and of the steel belt in extremely thin layers and ensure the separation of the granules and influence the shape of the melt granules in such a way that they preferably have a spherical shape and thus also have very little contact with the surface of the steel belt.

The melt granulation is preferably effected as described in US 6398989 and US 4279579 and in the brochures ik — lhr Partner in der Schmelzengranulierung", !GER 10.2003 and “Sandvik Process Systems — lhr Partner in industrieller Verfahrenstechnik’, PS—400 GER 2.2011, each published by the Sandvik group (\MMNsmtsandvikcom), more preferably using the apparatuses specified in these documents. Most preferably, the inventive use is effected with a machine as shown in the schematic diagram on page 13 of the brochure “Sandvik —- lhr Partner 1O in der Schmelzengranulierung”, PS-442/GER 10.2003. Explicit reference is made to the aforementioned documents with regard to the apparatus used and basic procedure. in the case of the inventive use, preference is given to using a steel belt cooler. A melt of the nce to be granulated is preferably applied to the steel belt, and the melt is cooled on the steel belt below the g ature or the fication temperature by preferred cooling of the steel belt from below by means of a coolant, preferably water, and is thus solidified.

Preferably, the inventive release agent is applied to the steel belt before the ation of the melt. The release agent can be applied to the steel belt, for example, by spray application of the release agent. The amount of the release agent can be selected freely within wide ranges.

The examples adduced hereinafter be the present invention by way of example, without any intention that the invention, the range of application of which is evident from the l description and the claims, be restricted to the embodiments specified in the examples.

The mode of action of the present invention was tested in a realistic test and compared with conventionally used organomodified siloxanes and silicone oil emulsions. A laboratory system (from SANDVlK) was employed, which contains a Rotofon'ner® and a water-cooled steel belt (Rotoforrn system). The e agent constituent used was used to obtain a 14% by weight aqueous solution (mixture) as a release agent, which was sprayed continuously onto the steel belt. The feedstocks and the description of the separating performance can be found in Table 1. ation of an inventive organomodified siloxane A mixture of 28% by weight of nctional polydimethylsiloxane (where N = approx. 50 and 0.27% by weight of hydrogen) was initially d. To this was added 22.5% by weight of an allyl alcohol-started copolymer consisting of 48% by weight of ethylene oxide units and 46% by weight of propylene oxide units, prepared according to the prior art by a KOH-catalysed reaction.

Also added were 36% by weight of an allyl alcohol—started copolymer consisting of 72% by weight of ethylene oxide units and 24% by weight of propylene oxide units, and 13.5% by weight of an allyl alcohol-started copolymer consisting of 91% by weight of ethylene oxide. The mixture was heated to 90°C while stirring. 5 ppm of platinum was added in the form of a platinum catalyst (hexachloroplatinic acid). The monitoring of conversion by determination of the SiH value (gas tn‘c determination) gave 995% SiH conversion after 5 h.

Test conditions: Belt speed: 11.25 m/min rrner speed: 12 m/min Sulphurtemperature: 145°C Cooling water temperature: 222°C Steel belt width: 150 mm Cooling length of the conveyor belt: 2.4 m e agent: about 0.02 g of active substance consumed, which is 14% diluted per kg of sulphur Table 1: e agent constituent and test results Release agent constituent Description of tion performance A 14% by weight aqueous ne oil No easy separation, granules are ellipsoidal, emulsion composed of a polydimethylsiloxane the edges of which break easily. Residues of from Dow Coming designated D0200 with a the release agent build up. viscosity of 20 cSt.

An aqueous on, diluted to 14% by No easy separation, granules are ellipsoidal, weight, of the IPAC SRB PLUS release agent the edges of which break . Residues of from Sabah (the IPAC SRB PLUS product is a the release agent build up. 75% polydimethylsiloxane emulsion). 14% by weight aqueous solution of a Easy separation at first, which becomes more noninventive poiyether siloxane ing to difficult after 5 minutes. Melt granules deviating the prior art, TEGOPREN® 5863, from Evonik from a spherical shape are often ed, and Goldschmidt GmbH with the structure of the more frequently flat bodies. formula (I) where N=48, a=46, b=2, c=2, d=O, R1 is an allyl alcohol-started poiyether radical of the formula (II) where f=11 and g=14, and R2 is an allyl l—started poiyether radical of the formula (II) where f=36 and g=38.

Inventive product of the formula (I) where N = Very easy separation, no deterioration in 50, a = 40, b=3, cw, d=3, R1 is an allyl separation performance after es, no alcohol-started poiyether radical of the formula residues. Granules have homogeneous (II) where f=11 and g=8, R2 is an allyl alcohol- spherical shape. started poiyether radical of the formula (ll) where f=20 and g=5, and R3 is an allyl alcohol-started poiyether radical of the formula (H) where f=13 and g=0.

As can be inferred from Table 1, inventive organomodified polysiloxanes have much better separation properties than the release agents or release agent constituents known from the prior art to date.

Claims (26)

1. What is claimed is: 1.
2. Use of organomodified loxanes of the a (I) R4—fi-O—'——lSi—O-—~—!Si-—O—ISi—-O1'1 FRllRl-lill l _lRlR| | r j rm j rm r;|Sl—OTRfi—R4 R R a b d (l) where N: d+2=20t0210, a= 15t0205, 10 b= 1t012, c= 1to12, d= 1to12, the R radicals are each independently identical or different, aliphatic or aromatic hydrocarbyi radicals having 1 to 10 carbon atoms, 15 the R4 radicals are each independently identical or different R, R1, R2 or R3 radicals, the R1, R2 and R3 radicals are each independently different polyether radicals of the l formula (II) —iCH27—\—o—CzHfi—(oCaHs—>g /o-C4Hs—}1——COCH2CH}i——oR5 where 20 e is 3 to 11, f is 6 to 30, g is O to 15, h is 0 to 5, i is O to 5, 25 R5 are independently the same or different and are each a methyl, acetyl or hydrogen radical, as a release agent or release agent constituent in melt granulation.
3. Use according to Claim 1, wherein N = 30 to 100.
4. Use according to Claim 2, wherein N = 40 to 60.
5. Use ing to Claim 1, wherein a = 35 to 45, Use according to Claim 1, wherein b = 1 to 8.
6. Use ing to Claim 5, wherein b = 2 to 6.
7. Use according to Claim 1, wherein c = 1 to 8.
8. Use according to Claim 7, wherein c = 2 to 6.
9. Use according to Claim 1, wherein d = 1 to 8.
10. 10. Use according to Claim 9, wherein d = 2 to 6. 15
11. 11. Use according to any one of Claims 1 to 10, wherein the R radicals are methyl radicals.
12. 12. Use according to any one of Claims 1 to 11, wherein e is 3.
13. 13. Use according to any one of Claims 1 to 11, wherein f is 10 to 30.
14. 14. Use according to any one of Claims 1 to 11, wherein g is 0 to 10.
15. 15. Use according to any one of Claims 1 to 14, wherein the molecular weight of the polyether radical of the formula (ll) is greater than 200 g/mol.
16. 16. Use according to Claim 15, wherein the molecular weight of the polyether radical of the formula (ll) is from greater than 400 to 2000 g/mol.
17. 17. Use according to any one of Claims 1 to 16, n the proportion of ethylene oxide in 3O the polyether radical of the a (ll) is greater than 45% by mass in the polyether, and the percentage by mass of ethylene oxide in the polyether radical R2 is at least 9% by mass greater than the percentage of ethylene oxide in the polyether radical R1, based in each case on the polyether radicals of the formula (ll). 35
18. 18. Use according to any one of Claims 1 to 17, n the radicals of the formula (II) may each be formed ly, in a gradient or in blocks.
19. 19. Use according to any one of Claims 1 to 18, wherein the organomodified polysiloxanes of the a (I) are used as release agents in the form of aqueous solutions.
20. 20. Use according to Claim 19, wherein the aqueous solutions comprise from 0.5 to 50% by weight of organomod'rfied polysiloxanes of the formula (I).
21. 21. Use according to any one of Claims 1 to 20, wherein the organomodified polysiloxanes have a cloud point from 35°C to 60°C.
22. 22. Use according to any one of Claims 1 to 21, wherein sulphur is granulated in the melt 10 granulation.
23. 23. Use according to any one of Claims 1 to 22, wherein a steel belt cooler is used in the melt granulation. 15
24. 24. Use according to any one of Claims 1 to 23, n a steel belt is used and the release agent is applied to the steel belt before the melt is applied to the steel belt.
25. 25. Use ing to Claim 1, substantially as herein described with reference to any one of the Examples.
26. 26. Use according to any one of Claims 1 to 24, substantially as herein described.