Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1979-09-17
1982-06-29
Bleutge, John C.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
26099811, 524650, 524 5, 523116, 525363, 525329, C08K 322, C08K 340, C08K 509, A61K 506
Patent
active
043371868
DESCRIPTION:
BRIEF SUMMARY
This invention relates to hardenable compositions comprising a particulate ion-leachable silicate or aluminosilicate; to cement packs comprising a particulate ion-leachable silicate or aluminosilicate and a poly(carboxylic acid); to hardened cements formed by reacting the particulate ion-leachable silicate or aluminosilicate with the poly(carboxylic acid) in the presence of water; to processes for preparing such cements; to mixtures useful in preparing such cements; and to products formed by utilising the cements.
In our Complete Specification No. 1,422,337 we have disclosed that improvement in the rate of hardening of such cements, conventionally called "poly(carboxylate) cements", is obtained by the addition thereto of a chelating agent. Specifically, we have described and claimed a process for the production of a poly(carboxylate) cement which comprises mixing a water-soluble poly(carboxylic acid) having a relative viscosity from 1.05 to 2.00 with a cement powder in the presence of a water-soluble chelating agent and water to a give a plastic mass which rapidly hardens to form a poly(carboxylate) cement. We have also described and claimed poly(carboxylate) cement packs and cement-forming liquids for the use in such processes, as well as poly(carboxylate) cements formed by such processes.
It is desirable to be able to improve still further the control over setting times for poly(carboxylate) cements, particularly having regard to the diverse and often specialised applications to which these cements are increasingly being put.
According to the present invention, there is provided a hardenable composition which comprises (i) a poly(carboxylic acid) or precursor thereof (as herein defined); (ii) a particulate ion-leachable silicate or aluminosilicate reactable with (i) in the presence of water or set to a hardened composition; and (iii) a metal salt which accelerates the setting of the composition.
It has been found that certain silver (I) salts or barium salts, for example silver nitrate, barium chloride or barium fluoride, may be utilised in accordance with compositions of this invention. However, in general (iii) comprises a multivalent metal salt the cation of which either has a high ionic potential (ionic charge/ionic radius), generally above 2.1, or is capable of forming complexes. Apart from the above mentioned exceptions, it is found empirically that such cations are those of a metal less electropositive than sodium, generally having a standard electrode potential E.sub.ox.sup.o less than 2.6 volts. Suitable such salts are those of aluminum, cadmium, magnesium, mercury (II), silver (II) or zirconium, especially aluminium, magnesium, silver (II) or zirconium. Further suitable such salts are the fluorides, for example aluminium fluoride, magnesium fluoride, stannous fluoride, silver (II) fluoride or zinc fluoride.
Preferably, such salts (iii) are soluble in an aqueous solution of (i).
In accordance with a further aspect of the invention, there is provided a hardenable composition as hereinabove defined which further comprises a complexing agent soluble in an aqueous solution of (i). The complexing agent may comprise a fluoride ligand or, more preferably, a chelating agent. The chelating agent may comprises a plurality of carboxyl groups, for example aconitic, itaconic, maleic mellitic or tricarballic acid; it may also comprise at least one hydroxyl group. Particularly preferred such chelating agents comprise citric, malic or tartaric acid. A further suitale type of chelating agent comprises a multivalent metal chelate, the metal of which may suitably be the same as that in (iii), for example a beta-diketone chelate, such as is formed by aluminium or chromium, or an EDTA chelate, such as is formed by copper or zinc.
Such chelating agents are suitable present in an amount up to 20% by weight, preferably 0.1% to 10% by weight, especially 3% to 8 % by weight, based on the weight of (i).
Preferred hardenable compositions according to this invention are those which comprise a chelating agent as hereinabove
REFERENCES:
patent: 3814717 (1974-06-01), Wilson et al.
patent: 3856737 (1974-12-01), Foster et al.
patent: 3962267 (1976-06-01), Suzuki et al.
patent: 3986998 (1976-10-01), Schmitt et al.
patent: 4016124 (1977-04-01), Crisp et al.
patent: 4082722 (1978-04-01), Schmitt et al.
patent: 4089830 (1978-05-01), Tezuka
patent: 4107845 (1978-08-01), Lee et al.
patent: 4141144 (1979-02-01), Lustgarten
patent: 4154717 (1979-05-01), Kohmura et al.
patent: 4209434 (1980-06-01), Wilson et al.
Derwent Abs. 69496/U46, "Dental Cements . . . Chelating Agents to Accelerate Setting", Oct. 25, 1973.
Derwent Abst. 20238A/11, "Aqueous Hardening Soln for Dental Cement . . . ", Jan. 31, 1978, G. C. Shika Kogyo.
Journal of Dental Research, 55, No. 6, 1408-1413, Sep.-Dec. 1974.
Crisp Stephen
Wilson Alan D.
Bleutge John C.
Lilling Hebert
National Research Development Corporation
LandOfFree
Hardenable compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hardenable compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hardenable compositions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2164349