COMPOSITIONS AND METHODS FOR SEALING JOINTS

Abstract: Joints are sealed by applying a mixture of a resin and a water-swellable filler, and allowing water to contact the applied mixture. The mixture which is storage stable and can be sealed in a one-pack container, can be provided in admixture with a volatile organic solvent which may need to be allowed to dry off before allowing contact with water. Alternatively, the mixture can be applied hot, the resin being thermoplastic, either directly to the or each member of the joint or to an impregnatable matrix which is subsequently applied.

Description: COMPOSITIONS AND METHODS FOR SEALING JOINTS This invention relates to compositions and methods for sealing joints. When joints are formed between two surfaces, it is often desired that they should be watertight. Examples of such joints are the interlocks between sheet steel piles used in coffer dams, retaining walls, river frontages, land reclamation and sea defence works. In the majority of cases, the pile interlocks prevent the passage of all but insignificant quantities of water. If installation procedures are not carried out correctly, however, or for various other reasons, significant leaks may develop; pumps then have to be installed and costly delays result. There are known methods of sealing such leaks, including dumping fly ash into the surrounding water and allowing seepage to carry the ash into the leak, eventually blocking it. Other methods include caulking with lead wool, sheeting with polythene and welding. Such methods are time-consuming and largely outside the engineer's control. It has been proposed to apply to a joint a sealing composition comprising a resin and a material which swells on contact with water. The composition must be protected from water prior to forming the joint. When the joint is formed and comes into contact with water, the material swells and seals the joint. Problems can arise with brushable sealants, owing to the length of time it takes for them to dry. The sealant must therefore be coated onto the surface a considerable time before forming a sealed joint, an< ^ the coating must be protected from water until the sealant is air dry. This may be difficult on building sites and can cause problems because of the area required to store the treated surfaces. Nevertheless, because of the convenience and ease of application of such systems they have found wide acceptance, although it appears to have been generally accepted that a "two-pack" system is required. For example, one pack may contain a resin, a filler and a swellable material, and the other a thinner; the packs are mixed immediately prior to use, involving the usual possibility of errors in mixing, the mixture then being applied, allowed to dry, and finally to swell on contact with water. According to a first aspect of the present invention, a composition for use in sealing joints comprises a resin, a material which swells on contact with water, and a volatile organic solvent, in a closed or sealed container. The "one-pack" system of the type defined can be stored, e.g. in a steel drum,and avoids the problems associated with "two-pack" systems. The composition can have a viscosity of 5 to 250 Ps and this makes it suitable for application to the surface to be coated by brushing. The thickness of the coating may be up to 8 mm but is not usually more than 3 mm in any one application. After application, the composition is allowed to dry before being allowed to come into contact with water, in conventional manner. Alternatively, a lower proportion of solvent can be used, so that the composition has a viscosity of 2,000 to 20,000, e.g. 8,000 to 15,000, Ps. Such compositions can be applied to the surface to be coated or directly to the joint formed by the abutment of two members. The proportion of solvent can be chosen so that, although the composition is suitable for easy application at normal ambient temperatures, there is no need to have to allow the composition to dry before allowing it to come into contact with water. These more viscous compositions can be applied in greater thickness than the less viscous compositions of the invention, e.g. up to 8 mm in one application, and are particularly suitable for use on concrete. The compositions described may often consist essentially solely of the resin, a water-swellable filler and the solvent. The storage stability of the compositions described above may be improved by including an anti- settling material, e.g. in an amount of up to -\ % by weight of the composition. A hydrogenated castor oil is suitable. The volatile solvent may be any solvent which will evaporate from the composition within 48, and preferably 24, hours at ambient temperature, e.g. 20°C. Suitable' solvents include ketones, e.g. alkyl, and particularly methyl alkyl, ketones . The nature of the solvent and indeed the other constituents may be chosen with regard to the place of use of the composition and the prevailing conditions although the composition will often be applied,under conditions which can be controlled, o one of the members forming the joint and allowed to dry before that member is brought into contact with the or* each other member of the joint. The relative amounts of the resin and swellable material will be chosen having regard to the need that, on contact with water, the composition should swell by a factor of at least 2, and preferably 3. According to a second aspect of the present invention, in a method for sealing a joint by applying to at least one of the members of the joint a mixture of a resin and a material which swells on contact with water, the resin is thermoplastic and the mixture applied at a temperature at which the mixture is flowable. The method of the invention, in which the sealant is applied hot, avoids the use of a solvent and the disadvantage of having to allow the applied composition to dry. In the hot application method, spraying can be used, and the applied material may be allowed to come into contact with water almost immediately, thereby cutting down the time from application to the formation of a seal and avoiding the need to protect the applied material from water. The nature of the resin will be chosen such that it is essentially solid under storage conditions, e.g. at 20 C, but flowable at the temperature of application which will usually be from 50° to 200°C, e.g. 100 to 160°C. It is generally preferred that the viscosity of the mixture should be no more than 50 e.g. 15 to 20, Ps at tne temperature of application e.g. at 125°C. According to a third aspect of the present invention, a composition for use in sealing joints comprises a matrix impregnated with a mixture of a resin and a material which swells on contact with water. The impregnated matrix system of the present invention allows easy storage and simple use of the sealing material. For example, the impregnated matrix can simply be inserted as a caulk into a joint which can immediately be allowed to come into contact with water, thereby swelling the swellable material and sealing the joint, The- impregnated matrix system is parallel to the method invention described above in that it avoids the use of a solvent and in that the impregnation will usually be achieved by impregnating the matrix with the mixture at a temperature at which the latter is flowable. For example, a strip of the impregnatable material may be passed through a bath of the hot mixture. Suitable impregnatable materials are woven and non-woven materials of natural or synthetic fibres having a void volume sufficiently large to allow both impregnation and swelling of the i pregnant when contacted with water. A particularly suitable matrix material is hessian. This may have a thickness of 1 to 10 mm and is preferably flexible, even after impregnation, so that it may be rolled up for easy storage. By way of general example, the resin may be melted in a bath, whereupon a swellable filler is stirred in. A strip of, say, hessian is then passed through the molten mixture and through a slit, thereby controlling the thickness of the impregnant, and taken up on a roller, A release paper can be used to prevent the hot material sticking together. In use, the impregnated material may be applied around the end of a pipe or tunnel section before an adjoining section is pushed onto that end, the impregnated material then being in the joint. Water may be allowed to come into contact with the composition immediately, causing swelling and the formation of a seal which is reinforced by the presence of the .matrix. The binder may consist of one or more indene- coumarone resins in either solid or liquid form. Examples of other binders which may be used are hydrocarbon resins, e.g. petroleum-based hydrocarbon resins, resins produced by distilling cracker bottom residues, epoxy or other resins. The softening point of the resin must not be so high that the coating is too brittle, which would give poor adhesion and a composition which would easily chip off. Neither must it be so low that the coating is 'too soft. It has been found that resins having a minimum softening point of 0 or, preferably.40, C and a maximum softening point of 150 or, preferably 110, C as determined by the ring and ball (R&B) method are particularly suit- able. It is often desirable to achieve the most appropriate softening point by using a mixture of the same or different resins, one resin having a softening- point (R&B) in the preferred range and another resin- having a viscosity of 5 to 250 poise at the temperature of application, e.g. 20 C when a solvent is used. Suitable fillers have been found to be derivatives of cellulose, including methylcellulose and hydroxypropylmethylcellulose. Carboxymethylcellulose (CMC) , optionally in the sodium form, and hydroxyethyl- cellulose have been found to be particularly suitable. The weight ratio of binder to filler may vary from 1:3 to 4:1 and usually from 1:1 to 4:1. If a filler of greater swellability than those given is used, this ratio.may be up to 20:1. The amount of solvent may be up to 501, or more usually 40 , by weight of the total composition, usually being at least 5% - and often at least 101, by weight (when present). The invention is illustrated by the following Examples, in which all parts and percentages are by weight unless otherwise specified. The R&B values were determined O P by the STPTC method PT3. The viscosity values were determined using a Brookfield viscometer, Spindle 4 at 20 C (speed 30 for 2 minutes for less and speed 1.5 for 10 minutes for more viscous compositions) . 5 Example 1 A brushable sealant was prepared, having the following composition:^ CMC 37.2 Indene-Coumarone Resin (100°C R&B) 30.8% 10 Indene-Coumarone Resin (150 Ps viscosity at 20°C) IS.01 Methyl Ethyl ketone 14.0$ 1 % , based on the resultant composition, of "Anti-settle CVP" (Cray Valley Products) was then added. -> r The sealant was stored in a sealed container until used. When applied by brush to a steel surface, a 1.3 mm thick coating was formed, and this was hard dry in 24 hours. When immersed in salt water, the coating swelled to a thickness of 5-7.5 mm, an expansion of 4-6 times. 0 The swollen coating was firm and remained so. Example 2 A formulation was prepared from 80$ of a solvent- based epoxy resin from CIBA, type GZ 488 N40 (40% resin in methyl ethyl ketone) , and 20% of a carboxymethylcellul- 25 ose filler, Cellofas B50 from I.C.I. 1%, based on the resultant composition, of Anti-settle CVP was then added. The composition was brushable at normal temper¬ atures and, when applied to steel, dried in 12 hours to give a coating having a thickness of about- 1.3 mm. When 0 immersed in water the coating swelled rapidly to a thick¬ ness of about 5 mm. Example 3 A formulation was prepared from a blend of 10 parts GZ 488 N40, 5 parts LAO (a liquid indene/coumarone 5 resin with a viscosity of 150 Ps at 20 C) and 6 parts of a hydroxyethylcellulose filler (Natrosol 250HR.,supplied by * ^URE ^ 3MPI Λ,. IPO < - Hercules Powder Co.). 1%, based on the resultant compo¬ sition, of Anti-settle CVP was then added. This formulat¬ ion could be stored. When applied by brush to a steel surface, the coating dried in about twelve hours to a thickness of about 1.3 mm. When immersed in water, the coating rapidly swelled to about 4 times its original thickness. Example 4 In this Example, the resin comprised a blend of indene-coumarone resin LAO and a hard resin produced by distilling cracker bottom residues of petroleum origin. The filler also comprised a blend, carboxymethylcellulose grades LS 710 and BWS (supplied by Hercules Powder Co.). The formulation also contained Bentone 27 (an organic derivative of magnesium montmorinollite) which acts to stabilise the suspension. The .formulation, which could be stored, was made up as follows: Methyl ethyl ketone 10.2 parts Methyl isobutyl ketone 6.8 parts Distilled cracker bottom residues (100°C R&B) 35.0 parts LAO indene-coumarone resin 25.0 parts CMC LS 710 25.0 parts CMC BWS 5.0 parts Bentone 27 2.0 parts The formulation was applied by brush to steel to give a film thickness of about 1.3 mm which was fully dry in 24 hours. When immersed in sea water, the film swelled to 4 times its original thickness; in fresh water to 7.5 times the original thickness. Example 5 The same resin blend was used as in Example 4, with an additional liquid indene-coumarone resin (LA20, a low molecular weight copolymer of indene, styrene and coumarone; 20°C R&B). The filler was Hoechst XP (a sodium carboxymethylcellulose) . The formulation was made up as follows: Methyl ethyl ke*tone 15 parts Methyl isobutyl ketone 10 parts Distilled cracker bottom residues (100°C R&B) 30 parts LAO indene-coumarone resin 9 parts LA20 indene-coumarone resin 9 parts Hoechst XP 30 parts 1%, based on the resultant composition, of Anti-settle.CVP was then added. The formulation was applied by brush onto steel, giving a coating thickness of about 1.3 mm when dry after 24 hours. This swelled to six times its original thickness when immersed in water. Example 6 A formulation was prepared from: Indene-coumarone resin (90oC R&B) 38.5% * LAO Indene-coumarone resin 7.8% Methyl ethyl ketone 26.7% Sodium CMC LS 710 25.6% Anti-settle CVP .1.4% This material could be stored and used in the same manner as the formulation of Example 1. The swelling factor was at least 2. Example 7 A formulation was prepared from: Indene-coumarone resin (90 C R&B) 47.9% LAO Indene-coumarone resin 9.6% Methyl ethyl ketone 9.6% Sodium CMC 31.9% Anti-settle CVP 1 % The proportion of solvent in this formulation was lower than in the other solvent-containing formulations of the invention, as. exemplified in Example 1 to 6. The filler was therefore added to the resin-solvent mixture at OMPI a higher temperature than in those cases. The material, which could be stored, had a trowelable consistency and showed good adhesion to concrete. It couldbe used to seal concrete tunnels before the segments are pieced together. It proved unnecessary to let the material dry before allowing water to contact the material when applied at thicknesses up to 6 mm. Swelling began after a few hours and was complete in about 24 hours. Example 8 A- sealant was prepared having the following composition: CMC 27% Indene-coumarone resin (100°C R&B) 44a Indene-coumarone resin . (150 Ps viscosity at 20 C) 29% When this sealant was sprayed onto a steel surface at a temperature of 110 C, a hard dry surface layer having a thickness of 2 mm was formed almost immedi- ately. When immersed in fresh water, the coating swelled to a thickness of 13 mm, and expansion of 6.5 times. When immersed in salt water, the coating swelled to a thickness of 10 mm, an expansion of 5 times. The swollen coating was firm and remained so. Example 9 The formulation of this Example comprised a blend of two fillers, carboxymethylcellulose types Blanose T730 and BWS supplied by Hercules Powder Co. The formulation was made up as follows: Blanose T730 25.2 parts BWS 12.2 parts LAO indene-coumarone resin 34.0 parts Indene-coumarone resin (100°C R&B) 28.3 parts This formulation was hot brushed onto steel at 140 C to give a coating thickness of around 1.7 mm. When immersed in water immediately after application, the coating rapidly swelled to a thickness of 9 mm. Similar results could be achieved by spraying. Example 10 A formulation was prepared from: Indene-coumarone resin (90°C R&B) 50% LAO indene-coumarone resin 25% Sodium CMC 25% 5 kg of this formulation, prepared by stirring the filler into the molten resin blend, was used to treat approximately 10m of 10 cm wide hessian to give a finished product approximately 2 mm. thick. After passing the hessian through the formulation, release paper could, be applied and the material stored in a roll. The material could be used as a seal by simply laying it between the joints on concrete pipes or by hammering it into gaps in leaking steel piles, water then causing swelling.

Claims: Claims 1. A composition for use in sealing joints and compris a resin and a material which swells on contact with water, characterised in/the composition is provided in a closed container in admixture with a volatile organic solvent. 2. A composition according to claim 1 characterised by a viscosity of 5 to 250 Ps. 3. A composition according to claim 1 characterised by a viscosity of 2,000 to 20,000 Ps. 4. A composition according to any preceding claim characterised in that it consists essentially solely of th resin, a water-swellable filler and the solvent. 5. A method for sealing a joint by applying to at least one of the members of the joint a mixture of a resin and a material which swells on contact with water, and allowing water to contact the joint, characterised in that the resin is thermoplastic and the mixture is applied at a temperature at which the mixture is flowable, either directly to the or each member or to a matrix which is subsequently applied to the or each member.. 6. A method according to claim 5 characterised in that the mixture is applied directly to the or each .member by spraying. 7. A method according to claim 5 or claim 6 characteri in that the mixture consists essentially solely of the resin and a water-swellable filler. 8. A method according to any of claims 5 to 7 characterised in that the viscosity of the mixture at the temperature of application is 5 to 250 Ps. 9. A composition for use in sealing joints and comprising a mixture of a resin and a material which swells on contact with water, characterised in that the composition is provided in the form of a matrix impregnated with the mixture. 10. A composition according to claim 9 for use in the method of any of claims 5 to 8. 11. A composition according to claim 9 or claim 10 in which the m'atrix is flexible and, a.fter impregnation, is coated with a release paper and rolled up. 12. A composition for use in sealing joints and comprising a resin and a material which swells on contact with water, characterised in that the resin comprises a mixture of materials, one having a softening point of 0 to 150°C and the other a viscosity of 5 to 250 Ps at 20°C. 13. A composition according to any of claims 1 to 4 and 12 characterised- in that additionally comprises an anti-settling agent.

Inventors: BEDFORD D, MARKHAM H, MASON C
Applicants: BEDFORD D, BRITISH STEEL CORP, MARKHAM H, MASON C, BRITISH STEEL CORP LTD
Application year: 1980
Main classification: C09K3
IPC codes: C09K3