AU6743090A

AU6743090A - Fire rated urethane sealant

Info

Publication number: AU6743090A
Application number: AU67430/90A
Authority: AU
Inventors: Franklin Sidney Lord
Original assignee: Bostik Findley Australia Pty Ltd
Current assignee: Bostik Australia Pty Ltd
Priority date: 1989-11-29
Filing date: 1990-11-27
Publication date: 1991-06-26
Anticipated expiration: 2010-11-27
Also published as: AU626741B2

Description

FIRE RATED URETHA E SEALANT

This invention relates to a joint sealant for masonry and building purposes and, in particular, an improved fire rated urethane masonry and building sealant. The invention has specific application to masonry joints for concrete slabs and the like. Fire regulations for buildings dictate that in the event of a fire, the fire should be restricted to a specific area of the building as much as possible. This means that the building, εuch as,

10 motel units and hotel rooms etc., is made up of distinct fire rated modules wherein the fire is isolated to a particular module.

To this end, the joints of building slabs are sealed by acrylic sealants coupled with the use of fibrous _ις blankets. However, the fibrous blankets are considered to be a hazard to the health of tradesmen in installing and working with the material and has been banned from use on building sites in Australia.

Such sealants have properties lending themselves to ₂₀ straight forward application by a gun, the sealants having relatively high viscosity and low or non slump characteristics after application to a joint or like at normal or elevated temperatures. Furthermore, the curing time for the sealant may vary depending upon the amount of -_j. curing agent, however, normally such curing time is relatively slow, being of the order of some hours, and have non-pourous properties. The cured sealant retains sufficient flexibility after curing to be capable of taking up or absorbing relative movement between parts such as in a

30 building situation.

Attempts have been made to use acrylic sealants as a fire rated joining material, however, such sealants have poor elastomeric properties and outdoor exposure limitations. 5 The use of intumescent materials have been disclosed in the published art, for example US Patent Nos. 4380593 and 4529742 relate to foamed intumescent masses obtained by reacting polyisocyanates with a phosphate of melamine phosphate type or a cyanuric acid or derivatives.

US Patent No. 4839223 relates to a sealing element comprising a precompressed foam strip containing a heat expanding intumescent material.

US Patent No. 4740527 is based upon the addition of polyepoxide to isocyanate cross-linked intumescent masses or carriers.

It has been surprisingly found that a standard two part polyurethane sealant of polyhydric alcohol (polyether) variety is capable of reacting with an isocyanate under certain specified conditions in the presence of appropriate catalyst at room temperature not normally associated with having a good fire rating.

According to the present invention the sealant can be modified to have an excellent fire rating to meet exacting Standards yet retain good elastomeric properties essential in an effective building sealant.

To meet Australian Standard Specifications, a fire rated sealant (and the concrete or like material joined thereby) must withstand a temperature of 1200°C on one side of the wall for a given length of time restricting temperature build-up on the other side of the wall to 180°C for a given length of time, the length of time resulting in the fire rating applied to the wall and the joint. Thus, a time of four hours to raise the outer wall temperature by

180°C indicates a fire rating of four hours under Australian Standards Specification AS1530-4.

The aim of the present invention is to provide a urethane sealant having a good fire rating without compromising the normal elastomeric properties of the sealant material. Other objectives are to provide a tell-tale ultraviolet indicator to allow identification of genuine fire rated material used as a sealant.

There is provided according to the present invention, a fire rated polyurethane sealant of two part type, characterised in that it includes an intumescent material such as ammonium polyphosphate based flame retardant chemical (Chemical Composition NH₄P0₃)_n. Conveniently, an UV indicator such as UVITEX (Trade Mark) may be added to the composition for simple identification under ultraviolet light.

The invention will now be described in greater detail with reference to the accompanying example.

An excellent base sealant composition is available under the Trade Mark SEAL-N-FLEX 2650 NS which is a two part sealant wherein curing is induced by the addition of extra SOLUSEAL (Trade Mark 1217).

It has been surprisingly found that the addition of ammonium polyphosphate compound NH₄P0₃ together with additional amounts of catalyst compounds such as a phenyl mercury ester of CIO mono carboxcylic acid marketed under the trade mark THORCAT 535 will produce a sealant having excellent fire rating and flexing capabilities. That is it is still readily gunnable and can be worked in the same way as non-treated sealants such as those marketed under the Trade Mark SEAL-N-FLEX 2650NS.

It has been found that the fire rating efficacy is substantially directly related to the amount of polyphosphate compound inserted into the composition. Thus, approximately 1% of AMGARD MC an Albright & Wilson Trade Mark, or PHOSCHECK, a Monsanto Trade Mark, ammonium polyphosphate compounds will give approximately a one hour fire rating increasing to 4% by weight to give a four hour fire rating without effecting the normal properties of the base sealant composition relating to its flexing capability.

The curing time of the composition which may be increased may be corrected by the addition of extra catalytic material, such as, THORCAT 535.

It is also proposed to add ultraviolet indicator such as, that marketed under the Trade Mark UVITEX OB in sufficient quantity to be detected by an ultraviolet light detector.

An addition of small amounts of the UVITEX of approximately .3% by weight is sufficient for present purposes so that the sediment can be easily checked by an ultriviolet (black light) lamp as being the genuine sealant product .

It has been found that the addition of approximately .5% of THORCAT 535 is sufficient to reduce the curing time to that normally encountered without the addition of AMGARD polyphosphate composition to the SEAL-N-FLEX sealant. Because of small amounts of THORCAT 535 catalyst normally required the addition of the ammonium phosphate buffer calls for the application of larger amounts of THORCAT 535 in a given mixture and therefore results in improved accuracy and control over the application of the catalyst curing agent such as THORCAT 535.

It will be appreciated by those skilled in the art that the present invention provides a fire rated sealant in which adequate fire ratings are achieved to satisfy AS1530-4 whilst still retaining the essential properties of a good sealant composition for use in the building industry.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A fire rated polyurethane sealant of two part type, the sealant being of the polyhydric alcohol (polyether) type having relatively high viscosity and low slump characteristics suitable for use with a sealant gun, wherein one part is mixed with an intumescent fire retardant buffer material such as ammonium polyphosphate.

2. A sealant as claimed in Claim 1 wherein an ultraviolet indicator is added to the mixture.

3. A sealant as claimed in Claim 1 or Claim 2 wherein the buffering influence of the fire retardent material is counter-balanced by additional catalyst therein.