Dispersions of siliceous solids in liquid organic media

Claim 2

A composition comprising the following components (a-c) intimately mixed together (a) a particulate siliceous material having particles below 10 μm in their longest dimension, (b) a liquid or liquifiable polymerizable organic medium, (c) a dispersing agent containing a mixture of compounds comprising a phosphorus oxyacid having the formula ##STR7## wherein R 1 is an organic group containing a terminal chain which is either a hydrocarbon group having at least six carbon atoms or a polyether of molecular weight greater than 200 (preferably from 500-10,000) R 2 is either a group as specified for R 1 , a hydrogen atom, or a hydrocarbyl or substituted hydrocarbyl group not having a terminal chain of at least six carbon atoms and an organic basic nitrogen compound having the formula ##STR8## wherein Z 1 is a group as specified for R 1 before and Z 2 and Z 3 which may be the same or different, are as specified for R 2 before.

Claim 3

A composition as claimed in claim 1 wherein the siliceous material is silica.

Claim 4

A composition as claimed in claim 2 wherein the silica is a colloidal form.

Claim 5

A composition as claimed in claim 1 wherein the medium is an acrylate or methacrylate monomer.

Claim 6

A composition as claimed in claim 1 wherein the liquid or liquifiable organic medium contains functional groups reactive with condensation catalysts or promoters.

Claim 7

A composition as claimed in claim 5 wherein the functional group is a hydroxyl group.

Claim 8

A composition as claimed in claim 1 wherein the medium is a vinyl urethane.

Claim 9

A composition as claimed in claim 1 wherein the group R 1 in the dispersing agent mixture comprises a longchain alkyl group containing from 8 to 22 carbon atoms.

Claim 10

A composition as claimed in claim 1 wherein the group R 1 in the dispersing agent mixture contains a polyoxyethylene or polyoxypropylene chain.

Claim 11

A composition as claimed in claim 1 wherein the group R 2 in the dispersing agent mixture is a group identical to R 1 or is a hydrogen atom.

Claim 12

A composition as claimed in claim 8 wherein the group Z 1 is a long chain alkyl group containing from 8 to 22 carbon atoms.

Claim 13

A composition as claimed in claim 8 wherein the groups Z 2 and/or Z 3 are hydrogen, a lower alkyl group containing less than six carbon atoms, a phenyl or a benzyl group.

Claim 14

A composition as claimed in claim 1 wherein the molar proportions of acid to base in the dispersing agent mixture is from 0.5:1 to 100:1.

Claim 15

A composition as claimed in claim 13 wherein the proportion is from 1:1 to 3:1.

Claim 16

A composition as claimed in claim 1 wherein a silane reactive to the siliceous solid is present in the composition.

Claim 17

A composition as claimed in claim 15 wherein the silane is a silane containing polymerisable groups.

Claim 18

A dispersion of a siliceous solid in an organic medium made from a composition as claimed in claim 1.

Claim 19

A dispersion as claimed in either claim 15 or claim 16 wherein the dispersion contains from 5 to 90% by weight of the siliceous solid.

Claim 20

A dispersion as claimed in claim 20 wherein the silica has an average particle size below 1 μm.

Claim 21

A dental composition which is a fluid composition comprising: (a) a particulate siliceous material having particles below 1 μm in their longest dimension; (b) a liquid or liquifiable organic medium which is either a vinyl urethane or the reaction product of a bisphenol with a glycidyl alkacrylate (c) a dispersing agent containing a mixture of compounds comprising a phosphorus oxyacid having the formula: ##STR9## where R 1 is an organic group containing a terminal chain which is either a hydrocarbon group having at least six carbon atoms or a polyether of molecular weight greater than 200, preferably from 500-10,000, R 2 is either a group as specified for R 1 , a hydrogen atom, or a hydrocarbyl or substituted hydrocarbyl group not having a terminal chain of at least six carbon atoms and an organic basic nitrogen compound having the formula: ##STR10## wherein Z 1 is a group as specified for R 1 before and Z 2 and Z 3 , which may be the same or different, are as specified for R 2 and (d) a free radical generative catalyst for polymerisation of the organic medium.

Claim 22

A dental composition which is a fluid composition comprising: (a) a particulate siliceous material having particles below 1 μm in their longest dimension; (b) a liquid or liquifiable organic medium which is either a vinyl urethane or the reaction product of a bisphenol with a glycidyl alkacrylate (c) a dispersing agent containing a mixture of compounds comprising a phosphorus oxyacid having the formula: ##STR9## where R 1 is an organic group containing a terminal chain which is either a hydrocarbon group having at least six carbon atoms or a polyether of molecular weight greater than 200, preferably from 500-10,000, R 2 is either a group as specified for R 1 , a hydrogen atom, or a hydrocarbyl or substituted hydrocarbyl group not having a terminal chain of at least six carbon atoms and an organic basic nitrogen compound having the formula: ##STR10## wherein Z 1 is a group as specified for R 1 before and Z 2 and Z 3 , which may be the same or different, are as specified for R 2 and (d) a free radical generative catalyst for polymerisation of the organic medium.

Claim 23

A dental composition as claimed in claim 20 in which the vinyl urethane is a polymerisable prepolymer containing at least two polymerisable ethylenically unsaturated groups and being the reaction product of a urethane prepolymer and an ethylenically unsaturated monomer reactive with the urethane prepolymer.

Claim 24

A dental composition as claimed in claim 21 wherein the organic medium also contains 50 to 150% by weight of the vinyl urethane of at least one ethylenically unsaturated monomer.

Claim 25

A dental composition as claimed in claim 22 in which the free radical generative catalyst is activatable with radiation having a wavelength in the range 230 mμ to 500 mμ.

Claim 26

A dental composition as claimed in claim 23 in which the free radical generative catalyst is activatable with radiation having a wavelength in the range 400 mμ to 500 mμ.

Claim 27

A dental composition as claimed in claim 24 in which the free radical generative system comprises at least one photosensitiser selected from fluorenone, substituted derivatives thereof, and α-diketones having the structure ##STR11## in which the groups A, which may be the same or different, are hydrocarbyl groups or substituted hydrocarbyl groups and at least one reducing agent capable of reducing the photosensitiser when the photosensitiser is in an excited state.

Claim 28

A small container containing a composition as claimed in claim 23.

Claim 29

A composition comprising the following components (a-c) intimately mixed together (a) a particulate siliceous material having particles below 10 μm in their longest dimension, (b) a liquid or liquifiable polymerizable organic medium not containing acidic or basic groups, (c) a dispersing agent containing a mixture of compounds comprising a phosphorus oxyacid having the formula ##STR12## wherein R 1 is an organic group containing a terminal chain which is either a hydrocarbon group having at least six carbon atoms or a polyether of molecular weight greater than 200 (preferably from 500-10,000) R 2 is either a group as specified for R 1 , a hydrogen atom, or a hydrocarbyl or substituted hydrocarbyl group not having a terminal chain of at least six carbon atoms and an organic basic nitrogen compound having the formula ##STR13## wherein Z 1 is a group as specified for R 1 before and Z 2 and Z 3 which may be the same or different, are as specified for R 2 before.

Claim 30

A composition comprising the following components (a-c) intimately mixed together (a) a particulate siliceous material having particles below 10 μm in their longest dimension, (b) a liquid or liquifiable polymerizable organic medium not containing acidic or basic groups, (c) a dispersing agent containing a mixture of compounds comprising a phosphorus oxyacid having the formula ##STR12## wherein R 1 is an organic group containing a terminal chain which is either a hydrocarbon group having at least six carbon atoms or a polyether of molecular weight greater than 200 (preferably from 500-10,000) R 2 is either a group as specified for R 1 , a hydrogen atom, or a hydrocarbyl or substituted hydrocarbyl group not having a terminal chain of at least six carbon atoms and an organic basic nitrogen compound having the formula ##STR13## wherein Z 1 is a group as specified for R 1 before and Z 2 and Z 3 which may be the same or different, are as specified for R 2 before.