GB2403723A - Silicone room temperature vulcanizing (RTV) mould making composition with improved mould release characteristics - Google Patents

Abstract

A method of improving the mould release properties of a silicone RTV rubber mould making composition comprising i) a base polymer having reactive groups, ii) a crosslinking agent, iii) a catalyst, consisting of adding to the composition less than 3 % by weight of a metal salt of a fatty acid based on the weight of the base polymer. Preferred metal salts include stearates, palmitates and oleates, particularly calcium, zinc, magnesium, nickel, barium, aluminium and lithium stearates or mixtures thereof. Preferred compositions use condensation cure systems with i) a polyorganosiloxane containing silanol groups, ii) an organosilicon compound containing alkoxy groups and iii) a tin catalyst (e.g. dibutyl tin dilaurate). However, addition cure systems with i) a polyorganosiloxane containing alkenyl groups, ii) an organosilicon compound containing hydrogen atoms and iii) a platinum, iridium, palladium or ruthenium catalyst, may also be used.

Description

SILICONE ROOM TEMPERATURE VULCANIZING (RTV! RUBBER MOLD MAKING COMPOSITION

lIAVING IMPROVED MOLD RELEASE CHARACTERISTICS 10001] This invention is related to mould making, mould making compositions, methods of improving the mould release characteristics of silicone room temperature vulcanising (RTV) rubber mould making compositions, and to methods of making duplicate articles of manufacture by casting such compositions.

10002] Silicone rubber has been used for making moulds used for replication, prototyping, and short production runs for about 30 years. Duplicates made from silicone rubber moulds are highly accurate, exhibit extremely fine detail, and have excellent dimensional stability.

3] The applications of moulds made from silicone rubber mould making materials have been and include (i) the reproduction of figurines, jewellery, candles, and artefacts: (ii) the reproduction of fine art sculptures and statutes; (iii) the creation of silicone rubber pads for transfer printing; (iv) moulding flexible skins for animated robotic creatures, (v) making architectural reproductions; (vi) moulding and shaping food such as ice, chocolate, and candy; cake moulds, baking, moulds, pastry moulds and (vii) industrial mould making applications such as the reproduction of furniture parts, industrial tools, prototyping, and the fabrication of fake stone and other reconstituted stone items. Their ability to reproduce fine detail is the primary benefit of silicone mould making materials for art and craft reproduction.

4] Of paramount importance in mould making are concerns about mould life, stemming from desires to control costs and maintain an adequate production level. When more parts can be made from each mould, the cost for each copy decreases. In addition, the less often moulds have to be replaced, the less disruption there is to production processes.

5] The assignee of the present application has developed a continuous automated robotic laboratory operation system (CARLOS). CARLOS uses automated computer driven repeat castings of moulds made from silicone room temperature vulcanising (RTV) compositions, and is capable of evaluating material to failure about four times faster than previous techniques. CARLOS has greatly assisted industry in this regard. Using CARLOS, the present invention demonstrates a method and composition for resolving such concerns.

Thus, the invention relates to an improvement in mould release whereby the number of parts that can be made from individual moulds can be is increased.

10006] While US Patent 3,531,424 (September 29, 1970), i.e., the '424 patent, describes the addition of certain metal salts of fatty acids, i.e. , calcium stearate and zinc stearate, to silicone room temperature vulcanising compositions, the level of addition is much higher than the level according to the invention. Thus, the additive according to the '424 patent must be present at a level of at least 5 percent by weight based on the weight of the RTV. Furthermore, the purpose of the additive in the '424 patent is to (i) reinforce the RTV; and to (ii) improve the flow and slump characteristics of the RTV, i.e., when deposited on a vertical surface they show little tendency to sag (thixotropic).

100071 In contrast, and according to the invention, metal salts of fatty acids including calcium stearate and zinc stearate, are added to silicone room temperature vulcanising compositions at a lower level of addition than the level according to the '424 patent, i.e., less than about three percent by weight based on the weight of the RTV, preferably less than about two percent by weight, and most preferably less than about one percent by weight.

Furthermore, the purpose of the additive in the RTV composition according to the invention is to provide better mould release characteristics of the RTV to improve its mould life, rather than to reinforce RTVs or improve their flow and slump characteristics.

[00081 This invention is directed to a method of improving the mould release characteristics of a silicone room temperature vulcanising (RTV) rubber mould making composition containing (i) a base polymer having reactive groups, (ii) a cross linking agent, and (iii) a catalyst. The improvement relates to the addition to the silicone RTV rubber mould making composition, of less than about three percent by weight of a metal salt of a fatty acid based on the weight of the base polymer in the silicone RTV rubber composition, preferably less than about two percent by weight, and most preferably less than about one percent by weight.

10009] For most applications, the base polymer is an organosiloxane containing silanol groups or alkenyl groups in the molecule, the cross linking agent is an organosiloxane containing alkoxy groups or hydrogen atoms in the molecule, and the catalyst is tin or platinum based. The metal salt of a fatty acid is a stearate, a palmitate, or an oleate, but preferably a metal salt of stearic acid, such as calcium stearate, zinc stearate, magnesium stearate, nickel stearate, barium stearate, aluminium stearate, lithium stearate, or a mixture thereof.

10010] The invention is also directed to a method of making duplicate articles of manufacture in which materials are cast into moulds constructed of the above silicone room temperature vulcanising (RTV) rubber mould making composition. The casting material can be a polyurethane, polyester, epoxy, or plaster. The invention is further directed to the silicone room temperature vulcanising (RTV) rubber mould making composition containing the (i) base polymer having reactive groups, the (ii) cross linking agent, the (iii) catalyst, and (iv) less than about three percent by weight of a metal salt of a fatty acid based on the weight of the base polymer in the silicone RTV rubber composition, preferably less than about two percent by weight, and most preferably less than about one percent by weight.

1] These and other features of the invention will become apparent from a

consideration of the detailed description.

2] While the present application is directed to condensation cure systems (tin catalysed), the concepts of the present invention are also applicable to addition cure (otherwise known as hydrosilylation cure) systems (platinum, rhodium, iridium, palladium and ruthenium catalyzed/hydrosilation).

3] These systems are distinguished from one another in that in a condensation cure system, organosiloxane compositions that cure to yield cross linked elastomers are prepared by reacting (i) a polyorganosiloxane containing silanol groups with (ii) a cross linking agent comprising an organosilicon compound containing alkoxy groups, (iii) in the presence of a tin catalyst. Such condensation cure systems are known in the art and described, for example, in US Patent 5,556.914 (September 17, 1996), i.e., the '914 patent, as well as in the '424 patent referred to above.

100141 In an addition cure system, organosiloxane compositions that cure to yield cross linked elastomers are prepared by reacting (i) a polyorganosiloxane containing alkenyl groups with (ii) a cross linking agent comprising an organosilicon compound containing hydrogen atoms, (iii) in the presence of a platinum, rhodium, iridium, palladium or ruthenium catalyst. Such addition cure systems are also known in the art and are described, for example, in US Patent 5,373,078, EP0992195, EP1394200, W02004013230 and EP0061241.

One prior art addition cure material which states that it is suitable for use in the preparation of baking moulds is described in the Rhone- Poulenc Chemie Datasheets for SILBIONE RTV 71557 A & B (PEX) dated e.g. September 1994. Any suitable addition cure catalyst may be utilized including for example, platinum catalysts such as a fine platinum powder, platinum black, chloroplatinic acid, alcohol- modified chloroplatinic acid, a complex of an olefin and a chloroplatinic acid, a complex of a chloroplatinic acid and an alkenyl siloxane, or a thermoplastic resin powder that contains the aforementioned platinum catalysts; rhodium catalysts such as [Rh(O2CCH3)2]2,Rh(O2CCH3)3, Rh2(C'H'sO2)4, Rh(CsH7O2)3' Rh(C5H7O2)(CO)2, Rh(CO)[Ph3P](C5H7O2), RhX3[(R)2S]3, (R 3P)2Rh(CO)X, (R23P)2Rh(CO)H, Rh2X2Y4, HaRhbolefincCl, Rh (O(CO)R)3 n(OH)n where X is hydrogen, chlorine, bromine or iodine, Y is an alkyl group, such as methyl or ethyl, CO, CH'4 or 0.5 CH2, R is an alkyl radical, cycloalkyl radical or aryl radical and R2 is an alkyl radical an aryl radical or an oxygen substituted radical, a is 0 or 1, b is 1 or 2, c is a whole number from 1 to 4 inclusive and d is 2,3 or 4, n is 0 or 1. Any of the rhodium catalysts described in WO2004/013230 or EP0061241 may alternatively be used and Iridium catalysts such as Ir(OOCCH3)3, Ir(C5H7O2)3, [Ir(Z)(En)2] 2, or (Ir(Z)(Dien)]2, where Z is chlorine, bromine, iodine, or alkoxy, En is an olefin and Dien is cyclooctadiene. Typically, condensation cure systems are used for moulding figurines, decorative reproductions, and making transfer pads, whereas addition cure systems are used for engineering designs, prototyping, cake moulds, baking, moulds, pastry moulds and architectural fabrication. s

10015] While the present application is directed to polyurethane casting material, the concepts of the present invention are also applicable to other casting materials such as polyesters, epoxies, or plaster, for example.

1001 6l While the four examples used to represent this invention are set forth with reference to a particular composition of a condensation cure system, it should be understood that any condensation cure system and components thereof can be used, and the interested reader is referred to other condensation cure systems containing other types and categories of components, such as are described for example in the '424 patent and '914 patent, considered incorporated herein by reference thereto. Other curing systems such as peroxide cure systems may also be utilized and these require no cross-linker.

[00171 It should be noted that when an organosiloxane elastomer mould is used to make polyurethane castings, the curable polyurethane composition is poured or otherwise dispensed into the organosiloxane elastomer mould. The curable polyurethane composition cures to form the polyurethane casting. The casting is then pulled from the mould, and the process can be repeated to make another casting from the same mould. It has been found that curable polyurethane compositions may exhibit a tendency to leach or otherwise diffuse into organosiloxane elastomer moulds. As a result, as the curable polyurethane composition which is contained within the mould cures, the mould may begin to distort. Such distortion and the resulting deterioration of the mould can be progressive as additional polyurethane castings are made in the mould.

100181 Quite unexpectedly however, it has been found that distortion and deterioration can be minimized when organosiloxane compositions according to this invention are used to make the organosiloxane elastomer mould. Thus, when the organosiloxane elastomer mould is prepared using an organosiloxane composition containing a metal salt of a fatty acid, that the cure of the polyurethane composition which has leached into the mould can be reduced or inhibited all together. Accordingly, moulds experience less distortion and deterioration, and have longer lives.

10019] In compositions according to the present invention, the base may also contain a small amount of water. As is conventional, fillers and other optional components can be packaged either with the base, or with the curing agent, or with both, so long as the fillers and/or other optional components are substantially free of water.

10020] Curable compositions according to the invention are generally prepared by blending all of the components together. Typically, curing begins when the silanol, i.e., hydroxy functional, siloxane is mixed with the cross linking agent, in the presence of the condensation reaction catalyst. Complete cures may requires from several minutes to several hours, depending upon variables such as the type and concentration of the cross linking agent, and the particular type and concentration of the catalyst.

[00211 When compositions of the present invention are prepared in the form of two or more part systems, they can be made by preparing the base and the curing agent, and then combining and mixing the base and the curing agent. Curing will begin when the base and the curing agent are combined and mixed. In such cases, the mix ratio can vary, and is dependent upon the formulation of each part. Generally, however, mix ratios of about 1:1 to about 40:1 parts of the base per part of the curing agent, has been found to be adequate.

Some especially preferred mix ratios will typically be 1:1, 10:1, or 20:1.

10022] The following examples are set forth in order to illustrate the invention in more detail. Unless otherwise indicated, all parts and percentages in these Examples are by weight, and the viscosities are values measured at 25 C. [00231 In Comparative Example 1 and in Examples 1-3, a silicone elastomer mould was prepared by curing a curable composition. Each curable composition was prepared by admixing a base and a curing agent. Each base was prepared by admixing the first four components (i) to (iv). The admixture was then vacuum stripped for 2.5 hours at 170 C. The next two components (v) and (vi) were admixed with the stripped mixture, and the resulting mixture was cooled to 90 C. The remaining component (vi) was admixed with the cooled admixture, and the resulting admixture was filtered. In each Example, the curing agent was prepared by admixing all of the components. Each curable composition was prepared by admixing the base and corresponding curing agent at a mix ratio of 20:1.

10024] In Examples 1-3, a metal salt of a fatty acid was added to the base. The base was heated for 60 minutes at 120 C, blended, and allowed to cool to room temperature.

Each curable composition was then prepared by admixing the base and the curing agent.

Comparative Example I contained no metal salt of a fatty acid.

100251 Each silicone elastomer mould was prepared by pouring 45 grams of the curable composition into a master mould. The composition was then deaired under a vacuum of 29 inches of Hg (98,194 Pascal) for 4 minutes. Another 45 grams of the same curable composition was poured into the master mould and de-aired.

100261 The master mould consisted of an aluminium cone bolted to an aluminium support flange which had been sprayed with a commercial TEFLON@) mould release compound, and a polyvinyl chloride sleeve. The cone had a base of 1 3/16 inch (3 centimetre), a height of 2 3/4 inch (7 centimetre), three wedge shaped tapering cut sections, and 6 holes evenly spaced over the surface of the cone. Since the cone of the master mould had three wedge shaped tapering cut sections, the silicone elastomer mould made from the master mould had a corresponding number of wedge shaped tapering protrusions or vanes. In addition, since the cone of the master mould had 6 holes, the silicone elastomer mould made from the master mould had 6 corresponding cylindrically shaped projections or pegs.

[00271 The mould life of a silicone elastomer mould is the standard measure of the number of accurately reproduced parts that can be cast from a given mould. This can be determined using systems such as the continuous automated robotic laboratory operation system CARLOS noted above. Since the casting process can cause changes in the silicone elastomer mould, the number of parts or castings, which can be made from a single silicone elastomer mould is limited. Thus, as the number of castings which have been made from a particular silicone elastomer mould increases, so does the deterioration in the characteristics of the silicone elastomer mould. This deterioration can manifest itself in various forms.

10028] Some of the common forms of deterioration typically include changes in the physical dimensions or characteristics of the silicone elastomer mould. As the silicone elastomer mould changes, it follows that so do parts cast from such the mould. When changes in the silicone elastomer mould are of sufficient magnitude, the parts cast from such a mould will not constitute accurate reproductions of the master mould. Accordingly, the number of parts that can be produced from a given silicone elastomer before the parts are unacceptable is used to estimate the mould life of silicone elastomer moulds.

10029] Thus, changes in fine details such as the vanes or pegs of silicone elastomer moulds will be reproduced in the corresponding fine details of the castings. Such changes indicate that the silicone elastomer mould has begun to deteriorate. When the mould deteriorates to the point that castings produced from the mould are not sufficiently accurate, the moulder of necessity has to disrupt the process in order to replace the deteriorated mould.

10030] Evidence of such deterioration of silicone elastomer moulds used to illustrate this invention can first be detected at the line of the apex of the wedge shaped tapering cut of the casting. The first parts produced from the mould will have an apex which is a straight line. As the mould continues to deteriorate, the line of the apex of the wedge shaped tapering cut of the casting will begin to exhibit a wavy appearance. This wavy line appearance is due to changes in the line of the apex of the wedge shaped tapering protrusions of the mould.

10031] Terms used herein to evaluate deterioration are Start Wave, Medium Wave, End Wave, and Consecutive Chunking. Thus, (i) the number of castings that can be produced before the amplitude of the wavy line of the apex of the wedge shaped tapering cut of the casting becomes greater than 0.75 mm (750 micron) is the Start Wave; (ii) the number of castings that can be produced before the amplitude of the wavy line becomes greater than one mm is the Medium Wave; (iii) the number of castings that can be produced before the amplitude of the wavy line becomes greater than 1.5 mm (1,500 micron) is the End Wave; and (iv) the number of castings that can be produced before consecutive pieces of the elastomer can be pulled from the mould is Consecutive Chunking. This terminology is used in Table 1 to demonstrate the improved results according to the present invention.

10032] In mould making applications where fine details are critical, a silicone elastomer mould can only be used up to the point in time corresponding to Start Wave. Thus, the larger the number of parts that can be produced before Start Wave, the longer will be the mould life. Generally, in other applications, silicone elastomer moulds can be used up to the point in time corresponding to Medium Wave, in which case, the larger the number of parts that can be produced before Medium Wave, the longer will be the mould life. In some special applications, such as when fine details are not critical, silicone elastomer moulds can be used up to the point in time corresponding to End Wave, in which case, the larger the number of parts that can be produced before End Wave, the longer will be the mould life.

3] In yet less specialized mould making applications, silicone elastomer moulds can be used up to the point in time corresponding to Consecutive Chunking, in which case, the larger the number of parts that can be produced before Consecutive Chunking, the longer will be the mould life. Therefore, it follows that the larger the number of parts that can be cast from a silicone elastomer mould before the onset of Start Wave, Medium Wave, End Wave, or Consecutive Chunking, the greater will be the mould life of any particular silicone elastomer mould.

10034] These determinations can be obtained using the apparatus and procedures described for example in Publication No. 10-834B-01 (1998, 2000), ofthe Dow Corning Corporation, Midland, Michigan, entitled "CARLOS Brings Science to Mould Life Testing of RTV Silicone Rubber" by Edward Scott and Jeff Stolarczyk.

5] Except as noted below, the silicone elastomer moulds used in Comparative Examples l and in Examples 1-3 were prepared by allowing the curable composition to cure for 24 hours in a master mould. The aluminium cones were then removed and robotic CARLOS mould life testing was begun.

[00361 Mould life testing was completed by counting the number of casting that could be prepared from each silicone elastomer mould before Start Wave, Medium Wave, End Wave and Consecutive Chunking. The castings were prepared from a polyurethane casting resin.

In Examples 1-3 and in Comparative Examples 1, the polyurethane casting resin was prepared by admixing 12 grams of Alumilite's Regular Polyurethane Part A with 12 grams of Alumilite's Regular Polyurethane Part B. a casting resin composition available from the Alumilite Corporation, Kalamazoo, Michigan.

10037] The polyurethane casting resin was poured into the silicone elastomer mould and allowed to cure for ten minutes at room temperature to form a casting. The casting was pulled from the silicone elastomer mould with the release forces being recorded, and the casting was inspected for indications of Start Wave, Medium Wave, End Wave, Consecutive Chunking, and other defects. The procedure was repeated using the same cured silicone elastomer mould and a freshly mixed and cured polyurethane resin, until release forces exceeded 100 pounds (445 newton/N), or the silicone elastomer mould otherwise failed. The number of castings made with each silicone elastomer mould is shown in Table 1. In order to eliminate variability, the procedures were conducted using the robotic CARLOS mould life testing equipment referred to above.

Comparative Example I [0038] The base used in this example consisted of 100 parts of a base composition comprising (i) 20.6 parts by weight of a trimethylsiloxy terminated dimethylsiloxane having a viscosity of about 325 mm2/s (centistoke); (ii) 3 parts by weight of hexamethyldisilazane for hydrophobing the filler; (iii) 21.1 parts by weight of an amorphous precipitated crystal free silica gel filler having an average particle size of 6-8 micron (micrometer); (iv) 1.2 parts by weight of water; (v) 11 parts by weight of 5 micron zirconium silicate filler; (vi) 42.1 parts by weight of an hydroxy terminated dimethylsiloxane having a viscosity of about 10,000 centipoise (mPa.s); (vii) 1.1 parts by weight of a mixture containing about 52 % by weight of a trimethylsiloxy terminated dimethylsiloxane, 44 % by weight of water, and trace amounts of impurities such as alcohols, aldehydes, and glycols.

10039] The curing agent consisted of 5 parts by weight of a curing agent composition consisting of (i) 56 parts by weight of a trimethylsiloxy terminated dimethylsiloxane diluent; (ii) 40 parts by weight of tetraethylorthosilicate Si(OC2Hs)4 as the alkoxy group containing organosilicon cross linking agent; and (iii) 4 parts by weight of dibutyltin dilaurate catalyst.

Example I

10040] In this Example, which is according to the present invention, the base consisted of 100 parts by weight of the base used in Comparative Example 1, and one part by weight of calcium stearate. The curing agent consisted of 5 parts by weight of the same curing agent used in Comparative Example 1.

Examples 2 & 3

10041] These examples were the same as Example 1, except that in Example 2, zinc stearate was used instead of calcium stearate, and in Example 3, magnesium stearate was used instead of calcium stearate.

10042] The results obtained in the four examples are shown in Table 1.

Table I

Failure Criteria Comp. Example Example 1 Example 2 Example 3 Start Wave none 33 none none Medium Wave none none none none End Wave none none none none Consecutive Chunking 44 50 61 60 Pegs Left at Failure 2 6 Pound-Force at Failure 95 (422 N) 28 (124 N) 53 (235 N) 98 (435 N) Percent Improvement for 0 13 39 36 Consecutive Chunking [0043] Significant improvement can be seen in Examples 1-3 in which the composition contained a metal salt of a fatty acid, in comparison to Comparative Example 1, in which the metal salt was omitted.

10044] Other variations may be made in compounds, compositions, and methods described herein without departing from the essential features of the invention. The embodiments of the invention specifically illustrated herein are exemplary only and not intended as limitations on their scope except as defined in the appended claims.

Claims (1)

1. A method of improving the mould release characteristics of a silicone room temperature vulcanising (RTV) rubber mould making composition containing (i) a base polymer having reactive groups, (ii) a cross linking agent, and (iii) a catalyst, comprising adding to the silicone RTV rubber mould making composition, less than about three percent by weight of a metal salt of a fatty acid based on the weight of the base polymer in the silicone RTV rubber composition.

2. A method according to Claim 1 wherein less than about two percent by weight of the metal salt of a fatty acid is added to the silicone RTV rubber composition.

3. A method according to Claim 1 or 2 wherein less than about one percent by weight of the metal salt of a fatty acid is added to the silicone RTV rubber composition.

4. A method according to any preceding Claim wherein the base polymer is an organosiloxane containing silanol groups or alkenyl groups in the molecule.

5. A method according to any preceding Claim wherein the cross linking agent is an organosiloxane containing alkoxy groups or hydrogen atoms in the molecule.

6. A method according to any preceding Claim wherein the catalyst is tin or an addition cure catalyst comprising platinum rhodium, iridium, palladium or ruthenium based catalysts.

7. A method in accordance with claim 6 wherein the catalyst comprises one or more of a platinum catalyst such as a fine platinum powder, platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, a complex of an olefin and a chloroplatinic acid, a complex of a chloroplatinic acid and an alkenyl siloxane, or a thermoplastic resin powder that contains the aforementioned platinum catalysts; and/or a rhodium catalyst selected from [Rh(O2CCH3)2]2,Rh(O2CCH3)3, Rh2(CgH'sO2)4'Rh(CsH702)3, Rh(C5H7O2)(CO)2, Rh(CO)[Ph3P](CsH7O2), RhX3[(R)2S]3, (R 3P)2Rh(CO)X, (R 3P)2Rh(CO)H, Rh2X2Y4, HaRhbolefincCl, Rh (O(CO)R)3 n(0H)n where X is hydrogen, chlorine, bromine or iodine, Y is an alkyl group, such as methyl or ethyl, CO, CH4 or 0.5 CH'2, R is an alkyl radical, cycloalkyl radical or aryl radical and R2 is an alkyl radical an aryl radical or an oxygen substituted radical, a is 0 or 1, b is 1 or 2, c is a whole number from 1 to 4 inclusive and d is 2,3 or 4, n is 0 or 1; any of rhodium catalyst described in WO2004/013230 or EP0061241 and/or an Iridium catalyst selected from Ir(OOCCH3)3, Ir(C5H7O2)3, [Ir(Z)(En)2]2, or (Ir(Z) (Dien)]2, where Z is chlorine, bromine, iodine, or alkoxy, En is an olefin and Dien is cyclooctadiene.

8. A method according to any preceding Claim wherein the metal salt of a fatty acid is a stearate, a palmitate, or an oleate.

9. A method according to Claim 8 wherein the metal salt of a fatty acid is selected from the group consisting of calcium stearate, zinc stearate, magnesium stearate, nickel stearate, barium stearate, aluminium stearate, lithium stearate, and mixtures thereof.

10. A method of making duplicate articles of manufacture comprising casting a material into a mould constructed of a silicone room temperature vulcanising (RTV) rubber mould making composition containing (i) a base polymer having reactive groups, (ii) a cross linking agent, (iii) a catalyst, and (iv) less than about three percent by weight of a metal salt of a fatty acid based on the weight of the base polymer in the silicone RTV rubber composition.

A method according to Claim 10 wherein the silicone RTV rubber composition contains less than about two percent by weight of the metal salt of a fatty acid.

12. A method according to Claim 10 or 11 wherein the silicone RTV rubber composition contains less than about one percent by weight of the metal salt of I a fatty acid.

13. A method according to any one of Claims 10 to 12 in which the material is I selected from the group consisting of polyurethanes, polyesters, epoxies, and! plaster.

14. A silicone room temperature vulcanising (RTV) rubber mould making composition comprising (i) a base polymer having reactive groups, (ii) a cross linking agent, (iii) a catalyst, and (iv) less than about three percent by weight of a metal salt of a fatty acid based on the weight of the base polymer in the silicone RTV rubber composition.

15. A composition according to Claim 14 wherein the silicone RTV rubber composition contains less than about two percent by weight of the metal salt of a fatty acid.

16. A composition according to Claim 14 or 15 wherein the silicone RTV rubber composition contains less than about one percent by weight of the metal salt of a fatty acid.

17. A composition according to any one of Claims 14 to 16 wherein the base polymer is an organosiloxane containing silanol groups or alkenyl groups in I the molecule.

18. A composition according to any one of claims Claim 14 to 17 wherein the cross linking agent is an organosiloxane containing alkoxy groups or hydrogen atoms in the molecule.

19. A composition according to any one of claims Claim 14 to 18 wherein the catalyst is tin or platinum based.

20. A composition according to any one of claims Claim 14 to 19 wherein the metal salt of a fatty acid is a stearate, a palmitate, or an oleate.

21. A composition according to any one of claims Claim 14 to 20 wherein the metal salt of a fatty acid is selected from the group consisting of calcium stearate, zinc stearate, magnesium stearate, nickel stearate, barium stearate, aluminium stearate, lithium stearate, and mixtures thereof.

22. A composition in accordance with any one of claims 14 to 21 comprising a catalyst selected from one or more of one or more of a platinum catalyst such as a fine platinum powder, platinum black, chloroplatinic acid, alcohol modified chloroplatinic acid, a complex of an olefin and a chloroplatinic acid, a complex of a chloroplatinic acid and an alkenyl siloxane, or a thermoplastic resin powder that contains the aforementioned platinum catalysts; and/or a rhodium catalyst selected from [Rh(O2CCH3)2]2, Rh(O2CCH3)3, Rh2(CH'5O2)4, Rh(C5H7O2)3, Rh(C5H7O2) (CO)2, Rh(CO)[Ph3P](C5H7O2), RhX3[(R\S]3, (R23P)2Rh(Co)X' (R23P)2Rh(CO)H, Rh2X2Y4' HaRhbolefincCI, Rh (O(CO)R)3 n(OH)n where X is hydrogen, chlorine, bromine or iodine, Y is an alkyl group, such as methyl or ethyl, CO, CH'4 or 0.5 CH'2, R is an alkyl radical, cycloalkyl radical or aryl radical and R2 is an alkyl radical an aryl radical or an oxygen substituted radical, a is 0 or 1, b is 1 or 2, c is a whole number from I to 4 inclusive and d is 2,3 or 4, n is 0 or 1; any of rhodium catalyst described in WO2004/013230 or EP0061241 and/or an Iridium catalyst selected from lr(OOCCH3)3, Ir(C5H7O2)3, [Ir(Z)(En)2]2, or (Ir(Z)(Dien)]2, where Z is chlorine, bromine, iodine, or alkoxy, En is an olefin and Dien is cyclooctadiene.

24. A silicone mould made by curing a composition in accordance with any one of claims 14 to 23.

25. A silicone mould in accordance with claim 24 comprising a mould for making any one of a reproduced figurine, jewellery, candles, and artefacts, fine art sculpture and statues; a silicone rubber pads for transfer printing; a moulding for flexible skins for animated robotic creatures, an architectural reproductions; or an industrial mould for making reproduction of furniture parts, industrial tools, prototyping, and the fabrication of fake stone and other 26. A silicone mould in accordance with claim 24 for moulding and shaping food such as ice, chocolate, and candy; cake moulds, baking, moulds, pastry moulds.

27. A silicone baking mould product moulded using a mould in accordance with claim 26 and which comprises any suitable addition or hydrosilylation catalyst selected from one or more of one or more of a platinum catalyst such as a fine platinum powder, platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, a complex of an olefin and a chloroplatinic acid, a complex of a chloroplatinic acid and an alkenyl siloxane, or a thermoplastic resin powder that contains the aforementioned platinum catalysts; andlor a rhodium catalyst selected from [Rh(O2CCH3)2]2, Rh(O2CCH3)3, Rh2(CgHsO2)4, Rh(CsH7O2)3, Rh(CsH7O2) (CO)2, Rh(CO)[Ph3P](CsH7O2), RhX3[(R)2S]3, (R23P)2Rh(CO)X, (R23P)2Rh(CO)H, Rh2X2Y4'HaRhbolefincCl, Rh (O(CO)R)3 n(0H)n where X is hydrogen, chlorine, bromine or iodine, Y is I an alkyl group, such as methyl or ethyl, CO, CgH4 or 0.5 CaH2, R is an alkyl radical, cycloalkyl radical or aryl radical and R2 is an alkyl radical an aryl radical or an oxygen substituted radical, a is O or 1, b is 1 or 2, c is a whole number from 1 to 4 inclusive and d is 2,3 or 4, n is 0 or 1; any of rhodium catalyst described in WO2004/013230 or EP0061241 and/or an Iridium catalyst selected from Ir(OOCCH3)3, Ir(CsH7o2)3'[Ir(Z)(En)2]2, or (Ir(Z)(Dien)]2, where Z is chlorine, bromine, iodine, or alkoxy, En is an olefin and Dien is cyclooctadiene.

28. Use of a mould in accordance with claim 23 to make a mould for moulding and shaping food such as ice, chocolate, and candy; cake moulds, baking, moulds and, pastry moulds.

29. Use in accordance with claim 28 wherein the moulded product for moulding and shaping food such as ice, chocolate, and candy; cake moulds, baking, moulds and, pastry moulds is made with an addition or hydrosilylation catalyst selected from one or more of one or more of a platinum catalyst such as a fine platinum powder, platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, a complex of an olefin and a chloroplatinic acid, a complex of a chloroplatinic acid and an a]kenyl siloxane, or a thermoplastic resin powder that contains the aforementioned platinum catalysts; and/or a rhodium catalyst selected from [Rh(O2CCH3)2]2, Rh(O2CCH3)3, Rh2(CH5O2)4, Rh(C5H7O2)3, Rh(C5H7O2)(C0) 2, Rh(CO)[Ph3P](C5H702), RhX3[(R)2S]3, (R23P)2Rh(CO)X, (R23P)2Rh(CO)H, Rh2X2Y4, HaRhboIefincCl' Rh (O(CO)R)3 n(OH)n where X is hydrogen, chlorine, bromine or iodine, Y is an alkyl group, such as methyl or ethyl, CO, CH'4 or 0.5 CaH2, R is an alkyl radical, cycloalkyl radical or aryl radical and R2 is an alkyl radical an aryl radical or an oxygen substituted radical, a is 0 or 1, b is 1 or 2, c is a whole number from 1 to 4 inclusive and d is 2,3 or 4, n is 0 or 1; any of rhodium catalyst described in WO2004/013230 or EP0061241 and/or an iridium catalyst selected from Ir(OOCCH3)3, Ir(C5H7O2)3, [Ir(Z)(En)2]2, or (Ir(Z)(Dien)]2, where Z is chlorine, bromine, iodine, or alkoxy, En is an olefin and Dien is cyclooctadiene.