GB2353993A

GB2353993A - Binders for aggregates

Info

Publication number: GB2353993A
Application number: GB9921178A
Authority: GB
Inventors: Anthony Harold Hughes; Stephen Pennington
Original assignee: Sterling Technology Ltd
Current assignee: Sterling Technology Ltd
Priority date: 1999-09-09
Filing date: 1999-09-09
Publication date: 2001-03-14
Anticipated expiration: 2019-09-09
Also published as: GB2353993B; GB9921178D0

Abstract

Aggregate compositions, especially those for use in providing skid-resistance and other high-friction surfaces, are obtained by mixing and/or co-reacting a cement, a castor oil, a polyisocyanate and water. In preferred forms of the invention the cement is a hydraulic cement and the polyisocyanate is diphenyl methane diisocyanate (especially in the form known as "crude MDI") and/or tolylene diisocyanate. A mixture of a cement and a castor oil is also claimed. Honeycomb-like structures can be obtained by a method in which the binder composition is applied to a mass of pebbles, large pieces of aggregate or the like, and left to set.

Description

2353993 BINDER COMPOSITIONS This invention relates to binder compositions,

to processes for their preparation, to use of the binder compositions in aggregate compositions for example skid-resistant surfaces for roads and to methods for preparation of those aggregate compositions.

It has now been found, according to the present invention, that excellent aggregate compositions, especially high-friction aggregate compositions for use in skid-resistant road surfaces, can be provided by the use of binder composition derived from a cement, a castor oil, a polyisocyanate and water. It is believed that this reaction product has, or includes, a polyurethane structure or moities.

Thus, in one aspect the present invention provides a binder composition obtained by mixing/co-reacting:

a cement, a castor oil, a polyisocyanate and water.

Although various cements can be used it has been found convenient to use a hydraulic cement, for example that sold under the Trade Mark FERROCRETE by Blue Circle Cement Co. Ltd.

The castor oil used in the binder composition is 2 conveniently a commercial grade, for example that obtained from J.L. Seaton & Co.Ltd. under the trade mark "Castor Oil No. if'. The. composition of various castor oils is described in "Concise Encyclopedia of Chemical Technology" by Kirk-Othmer at pages 223- 224. The principal component of castor oil is a tri-glyceride of ricinoleic acid. If desired instead of the castor oil ingredient of the binder composition there can be used said triglyceride itself though, on the ground of expense, that alternative is in practice normally not convenient.

Examples of organic polyisocyanates which can be used are, for example, diphenyl methane diisocyanate (MDI) and tolylene diisocyanate (TDI). Where MDI is used as the polyisocyanate it is conveniently in the form of a commercial product (referred to herein also as "crude MDI11) which contains 4,4'- diisocyanatediphenylmethane and amounts of isomers and homologues of 4, 41diisocyanato-diphenylmethane. Other suitable forms of MDI are commercial grades of 4,41 dipheny1methanediisocyanate which may or may not include isomers and homologues and which may be "modified" by those skilled in the art (for example by inclusion of the uritonimine of MDI) and are sold commercially as modified MDI having isocyanate values between 20 and 33.6.

If desired, though this is normally not necessary, there can be used in the preparation of the binder composition an emulsifier and/or a catalyst for reaction of the polyisocyanate ingredient.

3 In the preparation of the binder compositions of the present invention the cement, castor oil, water and polyisocyanate ingredients can be introduced in various orders of sequence. In general, these procedures fall into two groups: first, where those four ingredients, together with any other ingredients used, are mixed together in a single stage; and secondly, procedures where the ingredients are introduced in succession. The latter procedures are preferred because they permit introduction of the cement in liquid form with the castor oil and/ or water; the use of such a liquid component facilitates mixing, particularly where a metered mixing and dispensing machine is to be used.

In one such multi-stage procedure the cement is used in the form of a dispersion in the castor oil to which is added the water and then the polyisocyanate (or alternatively the polyisocyanate and then the water).

In general, the cement, castor oil, water and polyisocycanate ingredients can be used in a wide variety of ratios. By way of example a preferred ratio, in which the parts are parts by weight, is as follows:

parts of a cement, for example a hydraulic cement parts of castor oil parts of water 25 parts of crude MDI By way of example, the ratios concerned in the preceding paragraph can be varied by using one or more of the following 4 proportions/amounts:

the cement:castor oil ratio is preferably at least the total weight of the cement and castor oil is preferably in the range 60 parts to 150 parts; the weight of water is preferably in the range 5 to 35 parts; the weight of polyisocyanate is preferably in the range 10 to 40 parts; the weight of cement is preferably in the range 35 to parts; the weight of castor oil is preferably in the range 10 to 75 parts.

It has been found that in some at least of the procedures described above foaming of the binder composition does not take place; for example, it does not take place when the polyisocyanate and water are introduced at the same time as the cement or when the polyisocyanate is added prior to the water. Use of a non-foaming binder composition is advantageous in preparation of a subsequent aggregate composition, in that the latter is stronger than where a foaming binder composition is used, thereby permitting use of a smaller amount of the binder composition. The non-foaming characteristic of some of the binder compositions of the present invention is surprising and is contrary to what would be expected bearing in mind the chemistry involved. Conventionally, reaction of water and polyisocyanate produces carbon dioxide. Thus, where in the present invention, a non- foaming product is produced it would appear that either the polyisocyanate does not react with the water or that any carbon dioxide produced is absorbed and/or trapped without giving rise to a foam. In any of these cases it is believed that the non-foaming is due to the presence of the cement; we have found that in the absence of the cement, substantial foaming occurs.

The dispersions or other mixtures of cement and castor oil disclosed herein are novel compositions and constitute an aspect of the present invention.

As the binder compositions of this invention are self curing, it is usually necessary to provide means. to prevent premature reaction, for instance in transit. Said means conveniently takes the form of physical separation of those ingredients which might otherwise react with each other.

Thus, a further aspect of the invention provides a system for use in the preparation of a binder composition of this invention, the system comprising:

6 A. a first component comprising dispersion or other p mixture of a cement and a castor oil; B. a second component comprising a polyisocyanate or precursor ingredients or reactants therefor; C. a third component comprising an aqueous material optionally including one or more emulsifiers and/or catalysts; components A, B and C being separate from each other so as to prevent any unwanted reaction.

In a still further aspect the invention provides a system for use in the preparation of a binder composition of this invention, the system composing:

A. a first component comprising a cement; B. a second component comprising a polyisocyanate or precursor ingredients or reactants therefor; C. a third component comprising an emulsion or other mixture of castor oil and water, said mixture optionally including one or more emulsifiers and/or catalysts; components A, B and C being separate from each other so as to prevent any unwanted reaction.

7 In a further aspect the invention provides a method of providing an aggregate composition in which an aggregate is mixed with a binder composition of the invention.

In particular the invention provides a method of producing a high-friction surface on a substrate, which comprises applying a layer of the binder composition to the substrate and distributing an aggregate on the binder composition layer.

The aggregate used can be, for example, any aggregate known for use in the preparation of skid-resistant or other high-friction surface. Suitable aggregates are those disclosed in HAPAS Roads and Bridges, Agr6ment Certificate No. 98/HO01 for Spraygrip High Friction Surfacing System.

The binder composition when cured is a hard, semi-flexible solid with unusual properties. It has similar compressive and tensile strength to that of concrete but unlike concrete, there is no inunediate catastrophic failure on excessive compression or on elongation.

These properties make it an ideal product f or use as a binder/adhesive for use in high friction road surfacing where it is spread whilst liquid and scattered with an aggregate, for example a bauxite. The deflection and compression characteristics allow some movement without allowing the scattered particles to be detached when, for example, vehicles brake whilst travelling over the surface.- Other types of particle can also be applied for decorative or demarcation 8 effects.

The binder composition of the invention can, alternatively, be used to coat pebbles or large pieces of aggregate which can then be left to set into a honeycomb-like structure.

Preferred embodiments of the binder composition of the present invention, its processes of preparation and its use in the production of highfriction surfaces are described, by way of example, in the following Examples in which all parts referred to are parts by weight unless stated otherwise.

EXAMPLE 1

A liquid dispersion was made of 75 parts of hydraulic cement ("FERROCRETE" ex Blue Circle Cement Co. Ltd.) in 30 parts of castor oil. (FERROCRETE is a Trade Mark). The cement- castor oil dispersion (105 parts) was then mixed for one minute with 20 parts of water and the resulting mixture was the mixed for one minute with 25 parts of a commercial grade of MDI (referred to also as "crude MDI). This crude MDI is a mixture of diphenyl methane diisocyanate containing proportions of isomers and homologues thereof. Foaming of the binder composition thus obtained was observed the solid foamed article being 1251 of the volume of the uncured mixed liquid.

EXAMPLE 2

9 Example I was repeated except that the order of mixing was changed, the cement-castor oil dispersion being mixed with the crude MDI (25 parts), for one minute, and the resulting mixture mixed with the water (20 parts), for one minute, to provide a binder composition.

No foaming of the binder composition thus obtained was observed.

EXAMPLE 3

An emulsion was made of 30 parts of castor oil in 20 parts of water. The castor oil - water emulsion was mixed for one minute with 75 parts of hydraulic cement ("PERROCRETE" ex Blue Circle Co. Ltd.). The resulting mixture was then mixed for one minute with 25 parts of the crude MDI described in Example 1 above. No foaming of the binder composition thus obtained was observed.

EXAMPLE 4

In this Example a binder composition was prepared by mixing in a mixing vessel and in a single stage, the following ingredients:

parts of castor oil 20 parts of water parts of hydraulic cement (Ferrocrete ex Blue Circle Co. Ltd) parts of the crude MDI described in Example 1 above The order of feed of the ingredients into the mixing vessel,.

prior to mixing, was: castor oil, followed in succession by the water, crude MDI and cement.

EXAMPLE 5

The binder composition of Example 1 was used to provide a high- friction surface by using the binder composition within five minutes of completion of its preparation, that is before any substantial amount of self-curing had begun. The binder composition was spread as a layer of thickness 1 to 2 nun on to a flat bituminous road surface as a substrate and then, within a further five minutes, there was distributed on to the binder composition layer an aggregate, for example Chinese bauxite. The aggregate was distributed so that the binder composition layer was wholly covered. When self-curing of the binder composition was complete excess aggregate was removed, for example by brushing or vacuum. The resulting composition was a coherent material having a high coefficient of friction.

The resulting surface treated road was subjected to the Transport Research Laboratory scuffing test for type 1 surfacing to Report 176 (appendix G) giving an erosion index of zero (0 best - 30 worst: pass mark </=3) and a texture index of 1.4 (pass >/=1.2) EXAMPLE 6 Example 5 was repeated except that the binder composition used was that of Example 2.

EXAMPLE 7

Example 5 was repeated except that the binder composition used was that of Example 3.

EXAMPLE 8

Example 5 was repeated except that the binder composition used was that of Example 4.

M306des.Ssa REP/mw A 1306

Claims

1. A binder composition obtained by mixing and/or coreacting a cement, a castor oil, a polyisocyanate and water.

2. A binder composition according to Claim 1, wherein the cement is a hydraulic cement.

3. A binder composition according to Claim 1 or 2, wherein the castor oil is a commercial grade castor oil.

4. A binder composition according to Claim 1, 2 or 3, wherein the polyisocyanate is an organic polyisocyanate.

5. A binder composition according to Claim 4, wherein the organic polyisocyanate is diphenyl methane diisocyanate and/or tolylene diisocyanate.

6. A binder composition according to Claim 5, wherein the organic polyisocyanate is crude MDI (as hereinbefore defined).

7. A process for preparing a binder composition as claimed in any of Claims 1 to 6, wherein the cement, castor oil, polyisocyanate and water are all mixed together in a single stage.

8. A process for preparing a binder composition as claimed in any of Claims 1 to 6, wherein the cement is pre-mixed with the castor oil or the water, and then to the resulting premixture the other ingredients are added.

91 A process for preparing a binder composition as claimed in any of Claims 1 to 6, wherein the cement is pre-mixed with the castor oil and then to the resulting pre-mixture there is added the water followed by the polyisocyanate.

10. A process for preparing a binder composition as claimed in any of Claims 1 to 6, wherein the cement is pre-mixed with the castor oil and then to the resulting pre-mixture there is added the polyisocyanate followed by the water.

11. A process according to any of Claims 7 to 10, wherein:

the weight of cement is in the range 35 to 150 parts; the weight of castor oil is in the range 10to 75 parts; the weight of polyisocyanate is in the range 10. to 40 parts; and the weight of water is in the range 5 to 35 parts.

12. A process according to Claim 11, wherein the total weight of the cement and castor oil is in the range 60 parts to 150 parts.

13. A process according to Claim 11, wherein ingredients are used in substantially the following amounts:

parts of a cement, for example a hydraulic cement; 30 parts of castor oil; 25 parts of crude MDI; and 20 parts of water.

14. A process according to any of Claims 7 to 13 wherein the cement:castor oil ratio is at least 1:1.

15. A system for use in the preparation of a binder composition as claimed in any of Claims 1 to 6, the system comprising:

A. a first component comprising a dispersion or other mixture of a cement and a castor oil; B. a second component comprising a polyisocyanate or precursor ingredients or reactants therefor; C. a third component comprising an aqueous material optionally including one or more emulsifiers and/or catalysts; components A, B and C being separate from each other so as to prevent any unwanted reaction.

16. A system for use in the preparation of a.binder composition as claimed in any of Claims I to 6, the system comprising:

17. A mixture of a cement and a castor oil, for use in a binder composition according to Claim 1.

18. A mixture according to Claim 17, wherein the weight of cement is at least that of the castor oil.

19. A mixture according to Claim 18, wherein the cement is present in an amount of substantially 75 parts by weight and the castor oil is present in an amount of substantially 30 parts by weight.

20. A method of producing an aggregate composition on a substrate, which comprises applying to the substrate a layer of a binder composition as claimed in any of Claims 1 to 6, and distributing an aggregate on the binder composition layer.

21. A method according to Claim 20, wherein the aggregate is one or more of those disclosed in HAPAS Roads and Bridges, Agr6ment Certificate No. 98/HO01 for Spraygrip High Friction Surfacing System.

22. A method of producing an aggregate composition, wherein a binder composition as claimed in any of Claims I to 6, is applied to a mass of pebbles, large pieces of aggregate or the like, which are left to set into a honeycomb-like structure.

23. A binder composition according to Claim 1, substantially as described herein.

24. A binder composition comprising a cement, a castor oil, a polyisocyanate and water, substantially as described herein.

25. A binder composition substantially as described in Example 1, 2, 3 or 4.

26. A process according to Claim 7, substantially as described herein.

27. A process for the preparation of a binder composition, said process being substantially as described in Example 1, 2, 3 or 4.

28. A system according to Claim 15 or 16, substantially as described herein.

29. A method according to Claim 20, substantially as described herein.

30. A method of producing an aggregate composition having a high friction surface, said method being substantially as described in Example 5, 6 7, or S.

REP/Mw A1306Claims29Aug.2000