Silicone elastomer material suitable for use in particular for making dental impressions

Abstract

Described are organopolysiloxane compositions that are capable of cross-linking and/or of hardening by polyaddition reactions so as to produce elastomers or materials made of silicone. Further described, is how the composition is useful for making a dental impression in the context of preparing prostheses.

Claims

1. A storable composition comprising: (a) 30% to 49.5% by weight, relative to the total weight of the composition, of at least one stabilizer D selected from the group of starches; (b) at least one polyorganosiloxane V-1 having a viscosity of between 1000 mPa.Math.s and 200,000 mPa.Math.s and having per molecule at least two alkenyl groups, which are each bonded to a silicon atom; (c) at least one polyorganosiloxane V-2 having a viscosity of between 10 mPa.Math.s and 1000 mPa.Math.s and having per molecule at least two alkenyl groups, which are each bonded to a silicon atom; and (d) at least one catalyst C which is a compound of a metal from the platinum group; wherein the composition has a weight ratio of polyorganosiloxane V-1 to polyorganosiloxane V-2 of from about 2:1 to about 1.2:1; and wherein the composition exhibits no blackening after 25 days at 60 C. and is storable for at least one year.

2. The composition as defined by claim 1, wherein the at least one stabilizer D is a corn starch, an acid-treated starch, a base-treated starch, a bleached starch, an oxidized starch, an enzyme-treated starch, a monostarch phosphate, a glycerol starch, a distarch phosphate esterified with sodium trimetaphosphate, a phosphated distarch phosphate, an acetylated distarch phosphate, a starch acetate esterified with acetic anhydride, a starch acetate esterified with vinyl acetate, an acetylated distarch adipate, an acetylated distarch glycerol, a hydroxypropyl starch, a hydroxylated distarch phosphate, a hydroxypropyl distarch glycerol, or a sodium starch octenyl succinate.

3. The composition as defined by claim 1, further comprising at least one compound selected from the group consisting of: a reinforcing filler Q1, a bulking filler Q2, a retarder or inhibitor I of polyaddition reactions, a polyorganosiloxane gum G having per molecule at least two alkenyl, groups which are bonded to the silicon, and having a viscosity of greater than 1000 mPa.Math.s at 25 C., a diluent comprising a polydimethylsiloxane F, a colorant K, a plasticizer P selected from the group consisting of liquid petroleum jelly and a paraffin, a wetting agent M, a silicone resin R, and a biocide N.

4. The composition as defined by claim 1, wherein the at least one stabilizer D is a corn starch.

5. The composition as defined by claim 3, wherein the wetting agent M is a surfactant.

6. The composition as defined by claim 3, wherein the polydimethylsiloxane F has a dynamic viscosity of between 10 mPa.Math.s and 5000 mPa.Math.s.

7. A mixture comprising the composition as defined by claim 1, wherein the composition of claim 1 is a part A and is mixed with a part B in a weight ratio of between 1:10 to 1:1, respectively, to obtain the mixture; wherein the part B of the mixture comprises: (e) at least one polyorganosiloxane H having per molecule at least two hydrogen atoms which are bonded to an identical or different silicon atom; (f) at least one compound V comprising a polyorganosiloxane having per molecule at least two alkenyl groups bonded to a silicon, wherein the number of hydrogen atoms bonded to the silicon in the polyorganosiloxane H to the total number of alkenyl unsaturation in the compound V is a ratio between 0.4 to 10; and wherein part A and part B are crosslinkable and/or curable by polyaddition reaction.

8. The composition as defined by claim 1, wherein the polyorganosiloxane V-1 further comprises: (a) at least two siloxyl units of formula: $\begin{array}{cc}{T}_a{Z}_b{\mathrm{SiO}}_{\frac{4-\left(a+b\right)}{2}}& \left(1.1\right)\end{array}$ in which: the symbols T are identical or different C.sub.2-C.sub.6 alkenyl groups, the symbols Z are identical or different monovalent hydrocarbon groups selected from the group consisting of an alkyl having 1 to 8 carbon atoms inclusive, optionally substituted by at least one halogen atom, and an aryl, and a is 1 or 2, b is 0, 1, or 2, and the sum a+b is 1, 2, or 3; and (b) optionally at least one siloxyl unit of formula: $\begin{array}{cc}{Z}_c{\mathrm{SiO}}_{\frac{4-c}{2}}& \left(1.2\right)\end{array}$ wherein: the symbol Z has the same meaning as above and c is 0, 1, 2, or 3.

9. The mixture as defined by claim 7, wherein: (1) part A further comprises at least one additive selected from: at least one polyorganosiloxane gum G having per molecule at least two alkenyl, groups which are bonded to the silicon, and having a viscosity of greater than 1,000,000 mPa.Math.s at 25 C., at least one reinforcing filler Q1 and/or one bulking filler Q2, at least one retarder or inhibitor I of polyaddition reactions, a diluent comprising at least one polydimethylsiloxane F blocked at each of the chain ends by a trimethylsilyl unit, at least one colorant K, a paraffin P, at least one biocide N, at least one wetting agent M, and at least one silicone resin R; and (2) part B does not comprise a catalyst C and further comprises at least one additive selected from: at least one stabilizer D selected from the group of starches, at least one polyorganosiloxane gum G having per molecule at least two alkenyl groups which are bonded to the silicon, and having a viscosity of greater than 1,000,000 mPa.Math.s at 25 C., at least one reinforcing filler Q1 and/or one bulking filler Q2, at least one retarder or inhibitor I of polyaddition reactions, a diluent comprising at least one polydimethylsiloxane F blocked at each of the chain ends by a trimethylsilyl unit, at least one colorant K, a paraffin P, at least one biocide N, at least one wetting agent M imparting a hydrophilic nature to the surface of said elastomer E or said material M, and at least one silicone resin R.

10. A material M or elastomer E obtained by crosslinking and/or curing the mixture as defined by claim 7.

11. A method of making dental impressions, pads employed in pad printing techniques, podiatric orthoses, or an impression of an auditory canal, the method comprising making the dental impressions, pads, orthoses or impression using the composition as defined by claim 1.

12. The composition as defined by claim 1, wherein the at least two alkenyl groups are vinyl groups.

13. The composition as defined by claim 3, wherein the at least two alkenyl groups are vinyl groups.

14. The composition as defined by claim 6, wherein the polydimethylsiloxane F has a dynamic viscosity between 20 mPa.Math.s and 1000 mPa.Math.s.

15. The mixture as defined by claim 7, wherein part A and part B are mixed by weight, in a ratio of 1 part of the composition and 5 parts of B.

16. The composition as defined by claim 9, wherein one or more alkenyl groups present in the composition are vinyl groups.

17. The composition as defined by claim 8, wherein the amount by weight of the catalyst C, calculated by weight of platinum metal, is from 100 ppm to 240 ppm based on the sum of the total weight of the polyorganosiloxane V-1 and polyorganosiloxane V-2.

18. The mixture as defined by claim 7, wherein the at least one compound V comprises a polyorganosiloxane V-1 and a polyorganosiloxane V-2.

19. A storable composition comprising: (a) 30% to 49.5% by weight, relative to the total weight of the composition, of at least one stabilizer D selected from the group of starches; (b) at least one polyorganosiloxane V-1 having a viscosity of between 1000 mPa.Math.s and 200,000 mPa.Math.s and having per molecule at least two alkenyl groups, which are each bonded to a silicon atom; (c) at least one polyorganosiloxane V-2 having a viscosity of between 10 mPa.Math.s and 1000 mPa.Math.s and having per molecule at least two alkenyl groups, which are each bonded to a silicon atom; and (d) at least one catalyst C which is a compound of a metal from the platinum group; wherein the composition has a weight ratio of polyorganosiloxane V-1 to polyorganosiloxane V-2 of from 1.97:1 to 1.1875:1; and wherein the composition exhibits no blackening after 25 days at 60 C. and is storable for at least one year.

Description

EXAMPLE

(1) a) List of starting materials used: Vinyl polyorganosiloxane V-1: polydimethylsiloxane oil blocked at each of the chain ends by a siloxyl unit (CH.sub.3).sub.2(Vi)SiO.sub.1/2, with viscosity of 100 000 mPa.Math.s (where Vi=vinyl group). Vinyl polyorganosiloxane V-2: polydimethylsiloxane oil blocked at each of the chain ends by a siloxyl unit (CH.sub.3).sub.2(Vi)SiO.sub.1/2, with viscosity of 600 mPa.Math.s. Polydimethylsiloxane (PDMS) F-1 blocked at each of the chain ends by a siloxyl unit (CH.sub.3).sub.3SiO.sub.1/2 and having a viscosity of 50 mPa.Math.s. Stabilizer D-1: corn starch. Paste 1: Mixture: vinyl polyorganosiloxane V-2 (polydimethylsiloxane oil blocked at each of the chain ends by a siloxyl unit (CH.sub.3).sub.2(Vi)SiO.sub.1/2, with viscosity of 600 mPa.Math.s)+a filler Q-1, which is a fumed silica surface-treated with D4 (octamethylcyclotetrasiloxane) in an 85:15 mixture by weight respectively. Wetting agent M-1: ester obtained by esterifying a C.sub.13 fatty acid (lauric acid) with a poly(oxyethylene) glycol containing approximately 9 OE units, having an HLB of 13.1, sold under the name Lincol PE 400 ML. Catalyst C-1: Platinum. Bulking filler Q2-1: Sicron SA 600: ground quartz with average particle diameter of 10 mm. Bulking filler Q2-2: Calcium carbonate Calofort-S. Bulking filler Q2-3: zeolite (Zeolite 4 A/S). Colorant K. Hydrogen polyorganosiloxane H-1: poly(dimethyl)(hydrogenomethyl)siloxane blocked at each of the chain ends by a siloxyl unit H(CH.sub.3).sub.2SiO.sub.1/2, having a viscosity of 300 mPa.Math.s.

(2) TABLE-US-00001 TABLE 1 Formulations of parts A of the two-component systems Components (p/w) Comparative 1 Comparative 2 Comparative 3 Comparative 4 Comparative 5 Example 1 Example 2 Example 3 Vinyl polyorganosiloxane V-1 19.0 19.0 19.0 19.0 19.0 13.8 19.0 19.0 Vinyl polyorganosiloxane V-2 16.0 16.0 16.0 16.0 16.0 7.0 16 16 PDMS F-1 15.5 15.5 15.5 15.5 15.5 15.0 15.5 15.5 Stabilizer D-1 22.5 22.5 22.5 0 22.5 34.0 49.5 49.5 Bulking filler Q2-2 27.0 27.0 22.0 0 27.0 0 0 0 Bulking filler Q2-1 0 0 0 39.5 0 5.0 0 0 Bulking filler Q2-3 0 0 5.0 10.0 0 0.0 0 0 Paste 1 0 0 0 0 0 25.0 0 0 Wetting agent M-1 0 0 0 0 0 0.2 0 0 Catalyst C-1 (ppm) 240 375 240 240 253 100 240 240 p/w = parts by weight

(3) TABLE-US-00002 TABLE 2 Single formulation for all of the parts B of the two-component systems Components (p/w) Amount parts by weight Vinyl polyorganosiloxane V-1 22.75 Vinyl polyorganosiloxane V-2 4.80 Stabilizer D-1 37.80 Paste 1 20.00 Wetting agent M-1 0.15 Polyorganosiloxane H-1 4.00 Bulking filler Q2-1 9.99 Colorant K 0.40

(4) For each two-component system under test, parts A and B, packaged in the form of cartridges, are placed in an oven and undergo accelerating aging at 60 C. After durations of 7 days and 25 days, the properties of the resultant materials are evaluated by crosslinking, at an ambient temperature at 23 C., a composition obtained by mixing 5 parts by weight of part B with one part by weight of a part A.

(5) Mixing can be carried out either by hand in a beaker or by means of a laboratory metering machine. Evaluation takes place after 7 days and 25 days at 60 C. of the following: the working time (W.T. in minutes and seconds) of the compositions resulting from the mixtures of parts A and B as set out above and in accordance with standard ISO 4823; the elastic memory in accordance with standard ISO 4823; and the Shore A hardness (SAH) after 8 minutes of crosslinking.

(6) After 25 days at 60 C., the presence or absence of blackening of the cartridge containing the catalyst (part A) is ascertained.

(7) The results are set out in table 3.

(8) TABLE-US-00003 TABLE 3 Properties measured for each material obtained from the two component systems Properties Comparative 1 Comparative 2 Comparative 3 Comparative 4 Comparative 5 Example 1 Example 2 Example 3 W.T. 200 145 155 210 205 145 142 150 SAH at t = 0 17.5 25.2 20 17.0 20.5 20.5 21 20 W.T. 155 Not 155 250 250 Not 200 205 SAH after 7 days at 60 C. 15.6 measured 19.0 18.5 13.5 measured 18 17 W.T./ Total inhibition; no elastomeric material is obtained 210 215 230 SAH after 25 days at 60 C. 15 15 11 Blackening of the cartridge YES YES YES YES YES NO NO NO containing the catalyst (part A) after 25 days at 60 C.

(9) Comparatives tests 1, 2, 3 and 5 show that even when the stabilizer D is present in part A, and at relatively high levels (22.5% by weight, relative to the total weight of part A), this does not prevent blackening of the cartridge containing the catalyst (part A) after 25 days of storage at 60 C. This is no longer the case for examples 1, 2, and 3 according to the invention, which no longer exhibit this problem of blackening of the parts A comprising the platinum catalyst. Moreover, after aging for 25 days at 60 C. of parts A and B before use, it is observed that the examples according to the invention produce an elastomer having a working time which is acceptable for use in the field of the taking of dental impressions.