AU598648B2 - A fire retardant coating - Google Patents

Description

AUSTRALIA

Patents Act 598648 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: This document contains the Priority amendments made under Section 49 and is correct for printing.

Related Art: APPLICANT'S REFERENCE: HA680994-004 Name(s) of Applicant(s): Fletcher Duroid Limited Address(es) of Applicant(s): 591 Great South Road, Auckland, NEW ZEALAND.

Address for Service is: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Complete Specification for the invention entitled: A FIRE RETARDANT COATING Our Ref 87372 POF Code: 9387/82313 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): 6003q/1 1 I- -i 9 -_I -2- This invention relates to improvements in and relating to building materials and more particularly to a water-based fire retardant coating or impregnating media for building membranes and the like.

This invention further relates to cellulosic and synthetic material formed for use other than as a building membranes and in which a degree of fire retardancy may be desirable or essential.

Products formed of cellulosic and synthetic materials, and suitable for use in building constr:ction and the like, are well known. It will be Coo 0appreciated that such products and materials are susceptible to heat, S~ 10 particularly fire. It is highly desirable, and indeed essential in many instances, that products and materials such as those referred to above So are made as resistant to fire as possible. A variety of techniques have previously been available which are adapted to confer a degree of fire retardancy to cellulosic and synthetic materials, and building products 'Voo 15 formed from such materials. These techniques have generally involved 0 the use of an aqueous or solvent medium as a carrier. While a number of S "o"o the previously known methods rely on a coating or impregnation 0 technique, other methods are adapted to occur during consolidation of o o the finished form of the product. An example of such a process would be o. 20 a method which occurs during a paper making process. A disadvantage 0 0 associated with known methods which involve the coating or impregnation of building products has been that to date only those techniques or methods involving impr.rgnation or coating from a solvent carrier medium has been able to confer sufficient fire retardant character to the product, while at the same time achieving the relatively high degree of performance required for breathable building materials and products, such as and including those products known as 'building membranes'.

L;ri 1-I r

"PYCW~~

it i i !n, it dP

'I

^1" I 4 'i o o j 1 0 4 i 4 4

E

i! IIo I 0 0 S0 0 0 o 0 8 00 14 ii j sr ii

I

j t a r r|

H

-3- The use of solvent carriers create problems in the manufacturing process due to the flammable and toxic properties of the solvents used.

Further problems encountered with the previously available and known coatings or impregnation media have related to: The sensitivity of certain fire retardant materials in the presence or passage of moisture or moisture vapour thus enhancing an effect of leaching migration, with subsequent deterioration in performance; (ii) The tendency of certain fire retardant materials to initiate reductions in terms of physical strength properties of cellulosic or synthetic materials to which they are applied.

Such effects may occur by way of chemical reaction of the ions of fire retardant materials, singularly or jointly, with the ions of the medium employed to achieve, or assist in the achievement of, solvation, dispersion, suspension or emulsification of such fire retardants. These effects may be accentuated by the processing requirements in terms of heating to facilitate drying, by removal of the transport and/or solvation medium, to complex, crosslink, precipitate or a combination of these which serve to form and/or fix a coherent layer of fire retardant material to or within the substrate.

L -L c i ilx~- l -4- To date, achieving the required level of performance and avoiding leaching and its associated deterioration in performance, has been difficult with water-soluble inorganic materials when used as the primary or preferred fire retardant or retardants. A further disadvantage relates to the previous limitations which have applied in the choice of conversion machinery used in applying previously available coatings and the like, and materials. Deterioration or swelling of the application or transfer, rubber or synthetic rollers of such machinery would be expected due to aggressive solvent attack from the chlorinated 10 aliphatic or aromatic hydrocarbon materials commonly used to solvate and/or disperse such fire retardant materials or their synergists.

It is an object therefore of one aspect of the present invention to o ,provide coating or impregnating media suitable for use in relation to building products such as building membranes and the like, which goes S 15 someway to overcoming, or at least minimising the above mentioned o 0 problems.

Further objects of the present invention will become apparent from the following description.

go According to one aspect of the present invention there is provided ooo oio:o 20 an aqueous fire retardant coating or impregnating medium, which comprises at least one aqueous dispersion or latex of at least one fire retardant; at least one fire retardant synergist; and at least one waterproofing/water repellency agent.

494 4 444,4 94 4 4 44 According to a further aspect of the present invention there is provided an aqueous fire retardant coating or impregnating medium, which comprises at least one aqueous dispersion or latex of at least one fire retardant; at least one fire retardant synergist; at lease one waterproofing/water repellency agent; and at least one further fire retardant in latex form in an aqueous carrier.

According to a still further aspect of the present invention there is providing a building product to which an aqueous fire retardant coating or impregnating medium has been applied, wherein said medium comprises at least one aqueous dispersion or latex of at least one fire retardant, at least one fire retardant synergist and at least one waterproofing/water repellency agent.

Further aspects of the present invention will become apparent from the following description, which is given by way of example only.

As described above, current methods used in providing fire retardant coatings or impregnation media for building membranes and such like formed from, for example, cellulosic and synthetic materials, only provide building membranes and such like with a sufficient fire retardant character, while achieving the relatively high degree of 20 performance required of breathable building membranes and such like, when impregnation or coating occurs from a solvent carrier medium.

The present invention provides impregnation or coating media which achieve a sufficient fire retardant character and achieve the relatively high degree of performance required, while using an aqueous medium. Use of an impregnation or coating medium according to the present invention further avoids or obviates leaching migration and subsequent deterioration in performance, which has been a problem with previously tried water-based coatings and impregnation media for such membranes.

44444 -n ~L i LIt1 -6 The coating or impregnation media provided by the present 'i invention are capable of producing coated, saturated or impregnated materials which exhibit satisfactory fire retardancy. Materials so produced have been found to be suitable alternatives to materials produced from solvent carrier media, for cellulosic substrates and the like.

A further advantage of the present invention is that coating or impregnation media according to the present invention are able to be applied from or in contact with a number of natural or synthetic rubber roll forms. This means that the previous limitations regarding choice of conversion machinery and materials, as described above, are avoided,.

i t In one preferred form of the invention, a coating of impregnation medium is formed, comprising an aqueous dispersion, or latex of at least one fire retardant material, at least one firm retardant synergist, at S 15 least one paraffin wax, or comparable waterproofing/water repellency agent and at least one further fire retardant material in latex form in an S, aqueous carrier.

I Suitable fire retardant dispersions include chlorinated hydrocarbon *i materials. Examples are Delvet 65 or Rex 0 Sperse A (Trade Marks).

20 Fire retardant dispersions including chlorinated hydrocarbons are -i i particularly efficacious when used in the present invention, however it is fi envisaged that other suitable fire retardant dispersions or latexes may also be used to advantage. The latexes referred to are of high halogen content, halogenated hydrocarbons such as Polychloroprene, Polyvinyl Chloride, Vinylidene chloride, alone, or copolymerised, or copolymerised with other halogenated hydrocarbons.

L 7- A preferred fire retardant synergist is antimony oxide. A further fire retardant synergist which may be used is aluminium trihydrate. In i. use, the fire retardant synergist may be incorporated using appropriate 1proportions to produce an aqueous slurry. This slurry may then be I 5 subjected to a technique such as ball milling or high speed dispersion, in i order to reduce the particle size and to remove or break down any agglomerates which may form when the slurry is produced from the solid ;I and liquid phases.

S The aforementioned slurry, produced according to method of the 10 present invention, may be prepared in the presence of a compatible ,viscosity control and suspending agent. Preferably, such a viscosity controlling suspending agent is provided in the form of a cellulosic, 444o0 water-soluble, material in an aqueous solution.

Particularly, but not exclusively, sodium carboxymethylcellulose may be used.

I u A wetting agent or surfactant may be added to the aqueous S' cellulosic solution prior to the addition of the solid phase of antimony oxide. This wetting agent or surfactant is used as a means of gaining o° ii wetting of the solid phase and thereafter maintaining dispersion of the i j 20 finished slurry. A suitable wetting agent or sufactant may be a Scompatible material of the anionic polyelectrolyte type. For example, i Carrybon L400 (Trade Mark) is particularly applicable, however it will be

I!

appreciated that other appropriate materials may also be used to advantage.

Preferably, the ratio of chlorinated hydrocarbon to antimony oxide or to antimony oxide/antimony trihydrate is such that maximum fire retardant efficiency is achieved. Examples will be given hereinafter.

-8- Furthermore, the ratio relative to antimony oxide or antimony oxide/aluminium trihydrate may be increased, while retaining preferable and desirable characteristics and physical properties of the product, for products wherein the fire retardancy requirements are less stringent.

Reference is now made to suitable latex substances which may be used. Preferably, such substances include polychloroprene, highly chlorinated vinyl acrylic copolymers, vinyl or vinyl vinylidene chloride copolymers with high chlorine content, or copolymers of these materials with other highly chlorinated hydrocarbons. The vinyl acrylic copolymer 10 is particularly efficacious, in that it increases the available halogen l content for fire retardancy and also promotes film hardness and durability.

0o a Examples of such substances include Haloflex 202 or 2025 (stabilised) and Haloflex 208 (Trade Marks).

i 15 Preferably, the one or more paraffin waxes, or comparable 0 00 waterproofing media added to the coating or impregnation medium of S, the present invention are added in the form of a dispersion. Again, such a dispersion is prepared according a method of the present invention.

A suitable paraffin wax dispersion or comparable waterproofing 20 media is preferably prepared in the presence of a compatible viscosity control and suspending agent. This may be in the form of a cellulosic, water-soluble material in aqueous solution.

An example of a suitable or appropriate viscosity control and suspending agent is sodium carboxymethylcellulose.

i 13-~1~ -9- In the case of paraffin wax, a wetting agent or surfactart is preferably added to the solution prior to the addition of the molten wax.

A suitable wetting agent or surfactant is, for example, a nonylphenol ethoxylate. Teric GN9 (Trade Mark) is an example of such a material, which cortains 9 moles of ethylene oxide.

A suitable paraffin wax according to the present invention may be a refined or semi-refined wax with a melting point in the range of approximately 50 to 65°C, and preferably in the range of 54 to 600C.

However, it should be appreciated that similar materials of higher melting point may also be used to advantage. Generally, waxes with a melting point above 900°C are less suitable.

The wax dispersion according to the present invention provides a convenient means of imparting water repellency to, for example, a dried coating according to the present invention, while at the same time 1' 15 maintaining inter-compatibility with the remaining components of the medium.

It should be appreciated that the order in which each prepared component is added to form a medium according to the present invention ;is not important when using suitable viscosity control and suspending 20 agents, in that all the components wrc'ld be mutually compatible.

A preferred form of a production process according to the present invention will now be described, by way of example only.

Firstly, a method or process for producing the antimony oxide or antimony oxide/aluminium trihydrate slurry will be described.

The dispersions referred to hereinafter may be prepared as will now be described, from weighed portions (or volumes for water).

I

S1- The antimony oxide or antimony oxide/aluminium trihydrate dispersion preferably includes components as follows:

I%

I

Antimony Oxide, 99% or 99.5% Pure 20-70 Aluminium Trihydrate, 200 mesh 0-50 Viscosity Control Agent Afterglow Suppressant 0-10 Surfactant/Wetting Agent 0-3 Biocide As required Water 20 (minimum) SI A weighed portion of viscosity control agent is first added to make 0 up water measured by volume or by weight. A weighted portion of o o a S antimony oxide, and aluminium trihydrate may then be added, while o a stirring the solution, until all the antimony oxide or antimony oxide and I 4 04 aluminium trihydrate has been added. A suitable afterglow suppressant may then be added in weighed portion, as required, for heavier t membrane products. Suitable afterglow suppressants may be of the boron or phosphorus type.

Stirring continues until the slurry as described is produced. The dispersion is then produced by application of more intensive shear methods, as previously described.

In a particularly preferred form of the invention, the slurry/dispersions prepared for addition to a coating or impregnation medium according to the present invention are given as follows for reverse roll coating.

-L -11- 1- 11 Antimony Oxide 60.0 i Surfactant/Wetting Viscosity Control Agent s Water 39.0 i «The above describes an antimony oxide only dispersion. When antimony oxide and aluminium trihydrate are used the slurry/dispersions are prepared as follows:- S Antimony Oxide 400 2 Viscosity Control Agent iThe degree of substitution of the viscosity control agents is preferably in the range 0.65 to 0.90.

As mentioned above, there is a tendency for agglomeration to occur. It is thus preferable that the viscosity control agent be incorporated in to the water component of the slurry/dispersion in one of two ways.

Firstly, the viscosity control agent may be added to the water component which is at 50 to 80° C, and thereafter stirred or dispersed to solvation by conventional stirring or dispersion techniques (for example high speed dispersion, propeller blade, ball or combination ball/paddle or continuous mixer).

L-r gO 12- The second method involves particulate contact with the solvating medium by means of a venturi draught system with an exit to a bulk stirring vessel, fitted with a driven propeller blade stir system, for homogenisation of the resultant solution. One known form of a method and apparatus utilizes what is known as 'THE HERCULES' (Trade Mark) apparatus.

A solution prepared by either of these methods may be incorporated into a solution containing other components of the dispersion from either relatively small volume or bulk volume storage.

10 In one preferred form of the invention, a suitable biocide may be added to obviate biological degradation of the viscosity control agent 0) and increase 'shelf life'.

0 It is advised that the solution produced be used rapidly to avoid viscosity reduction and variation from biological attack through longer o 00 oo 15 term storage.

o 00 0 Do To the solution resulting from the above, a weighed portion of wetting agent is added and incorporated by stirring, until the resulting solution is homogeneous.

Z* For an air knife or saturation process (impregnation) the preferred addition level of viscosity control agent is 0-0.3% w/w.

Preparation of a suitable wax dispersion will now be described.

This preparation is according to a method of the present invention. Such a suitable dispersion may be prepared from the following formulation: -13- ,0 Paraffin Wax 5-40 Surfactant Viscosity Control Agent Water 50-95 The degree of substitution of the viscosity control agent is preferably 0.65 to 0.90 for sodium carboxymethylcellulose, though not S exclusively.

10 When using paraffin wax, this has a semi or fully refined melting i point.

In one preferred form of the invention, an aqueous solution of viscosity control agent prepared from weighed portions of the agent and water, by volume or by weight, is produced. Either of the methods described for the antimony slurry may be used.

It is preferred that the temperature of the solution is brought to at least 50 C, prior to addition of the weighed, molten paraffin wax, in order to avoid shock cooling of the paraffin wax, with resultant agglomeration.

A weighed portion of surfactant is added to the aqueous solution, prior to addition of the paraffin wax, which is stirred until homogeneous. The weighed portion of the paraffin wax is then added, in a molten state, with high speed mixing. Such a system is preferable, as it reduces phase rejection or separation.

t~ i. -n -i i ii I -14- Once the paraffin wax has been added, the solution or mixture is preferably gradually cooled below the wax gellatiun/crystallisation point by use of cooling coils or similarly accepted heat transfer means. During such cooling stirring continues.

It would be appreciated that the dispersion will show evidence of agglomeration when cool, if only slow shear stirring is used. This form may, however, be broken to the smooth paste by high speed shear or stirring.

In one particularly preferred form of the invention, the wax dispersion comprises the following formulation: o *I 0 0 0 Wax 20.0 0 0 15 Surfactant Viscosity Control SWater 78.0 As mentioned previously, the coating or impregnation medium 20 according to the present invention may be prepared by incorporation of ieach of the components, the order in which mixing occurs being generally unimportant.

'A coating or impregnation medium according to the present invention may comprise the following general formulation: i ,i .L Chlorinated Hydrocarbon Dispersion 5-45 Antimony Oxide (or Antimony Oxide ATH) Dispersion 10-40 Polyvinyl Acrylic Latex 5-40 Polychloroprene Vinyl or Vinyl/Vinylidene or Vinylidene Chloride Latex 0-30 Dispersion of Paraffin Wax 2-10 t 10 Disperse or Dispersable Colourant 0-10 In one preferred form of the invention an inorganic pigment in a disperse or dispersable form be added, as a means of producing a colourant effect.

In one preferred form of the invention the ratio of antimony to available chlorine is 1:1 to 1:2.0.

When the components of the medium are brought together, no special provision needs to be made in order to homogenise the mixture. A propeller blade stirrer with adequately sized blades or driven horse power for the bulk envisaged would be adequate when running at a minimum of 200rpm.

In one particularly preferred form of the invention, a coating or impregnation medium would comprise the following: 0, membranes'.

-16w/w Chlorinated Hydrocarbon 36.4 Antimony Oxide (or Antimony/ATH) 32.4 I Polyvinyl Acrylic Latex 24.3 Paraffin Wax Dispersion Pigment Dispersion 1.9 i With regard to the antimony oxide or antimony oxide/aluminium trihydrate, the slurry preferably comprises solids at about 60% w/w.

A suitable pigment dispersion would be red iron oxide, such as for example Calink C8845F EX Tenneco (Trade Mark).

Preferably, the viscosity control agent comprises 0.45% 0.54% solution, based on the free water content.

Preferably the antimony oxide to available chlorine ratio is 1:1.28.

Description of application of a medium according to the present invention to a suitable building product, such as a building rrcmbrane or paper, will now be described.

When forming a breathable building membrane or the like, a medium according to the present invention may be applied to cellulosic 20 or other chosen roll (web) form or sheet form materials by methods well I known in the art for conversion, and well documented and established in commercial practice. The process by which the medium may be applied may be stated as direct or offset Rotogravure or Flexographic Printing method, coating by impregnation (saturation dip) with subsequent doctor wipe with air or contact means, air knife coating or reverse roller application means.

c I ~~I 17- In order to procce an adequate, pin hole free coating, the medium of the present invention may be adjusted to appropriate viscosity to perform the chosen conversion process. In other words, the medium may be adjusted in terms of absolute or kinematic viscosity by either adjustment of the initial addition level of viscosity control agent to the antimony oxide or antimony oxide/aluminium trihydrate slurry and consequently its relative dispersion, or the paraffin wax dispersion, or any of these.

The viscosity may be further or separately adjusted to the slurry or dispersion forms by addition or reduction in the addition rate of water as S' a carrier medium or by addition of extra water once the medium is produced.

In one preferred form of the invention, the medium may be applied in approximately equal proportion to both faces of an unsized, l27g/m2 00 0 15 natural saturation base paper and dried to about 4% finished moisture content. This results in a building paper having a Fire Retardancy Index compliant with AS 1503 pt 2 and service properties compliant with NZS 2295, Breathable Building Papers. The finished add on weight measured at 50% or total weight 190.5g/m2.

Thus, there is provided by the present invention water-based coating or impregnation media for, in one use thereof, building membranes, which goes at least some way towards overcoming problems previously encountered in fire retardant coatings for building membranes, or which at least provides the public with a useful alternative.

Although this invention has been described by way of example, and with particular reference to various embodiments thereof, it should be appreciated that modifications may be made thereto, without departing from the scope thereof as defined in the appended claims.

Claims (9)

1. 2. An aqueous fire retardant coating or impregnating medium as -laimed in Claim I wherein said waterproofing/water repellency agent comprises paraffin wax.
2. 3. An aqueous fire retardant coating or impregnating medium as claimed in claim I or claim 2 including at least one further fire retardant in latex form in an aqueous carrier. S 4. An aqueous fire retardant coating or impregnating medium as claimed in claim 3 wherein said further fire retardant comprises a halogenated hydrocarbon or a halogenated hydrocarbon copolymerised or copolymerised with other halogenated hydrocarbons. An aqueous fire retardant coating or impregnating medium as claimed in any one of the preceding claims wherein said fire retardant synergist comprises antimony oxide or aluminium trihydrate.
3. 6. An aqueous fire retardant coating or impregnating medium as S 0 claimed in claim 5 wherein said fire retardant synergist is provided in an aqueous slurry including a viscosity control suspending agent.
4. 7. An aqueous fire retardant coating or impregnating medium as claimed in claim 6 wherein said viscosity control suspending agent comprises sodium carboxymethylcellulose. B A -19-
5. 8. An aqueous fire retardant coating or impregnating medium as claimed in Claim 6 or Claim 7 wherein a wetting agent or surfactant is included with the viscosity controlling suspending agent.
6. 9. An aqueous fire retardant coating or impregnating medium as claimed in Claim 3 or any one of Claims 4 to 8 when dependent on Claim 3 wherein said further fire retardant comprises polychloroprene, highly chlorinated vinyl acrylic copolymers, vinyl or vinylidene chloride copolymers with high chlorine content, or copolymers of these materials with other highly chlorinated hydrocarbons. 1 0. An aqueous fire retardant coating or impregnating medium as claimed in any one of the preceding claims and substantially as herein described with reference to any one of the embodiments of the invention.
7. 11. A fire retardant material which has been coated or impregnated o with the coating or medium of any one of the preceding claims.
8. 12. A material as claimed in Claim I I comprising a building paper.
9. 13. A building paper substantially as herein described with reference to any one of the embodiments of the invention. DATED: 21 March, 1990 PHILLIPS ORMONDE FITZPATRICK Attorneys for: FLETCHER DUROID LIMITED 0636P ^H ff 4; 'n A 44 4400 t f 1 G~ et l 6 V a P