AU737261B2 - Identification method - Google Patents

Description

P/00/01i1 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE

SPECIFICATION

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PATENT

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Invention Title: Identification method, The following statement is a full description of this invention, including the best method of performing it known to us: FHPMELC699260007.

2 D\99260008.6 D\99260008.6 1A IDENTIFICATION

METHOD

This invention relates to a method of producing a material so that it can subsequently be identified. In particular, it relates to a way of identifying the manufacturer of foam material used in furniture and bedding by incorporating into the material a selected marker that can subsequently be detected and associated with that particular manufacturer. It also relates to foam material which include markers that are identifiable with the manufacturer of the material.

Background of the Invention oleo S" Foam material is mass produced widely for use in the manufacture of an 10 extensive range and variety of goods. The foamed polymeric material, particularly foamed synthetic polymeric material, may be produced in situ, for example, o foamed polyurethane insulation in the walls of refrigerators, or be pre-prepared in large regular forms such as sheets or blocks and cut to the desired shape.

Foamed polymeric materials can differ vastly in their physical properties such as strength, dimensional stability, insulating properties and so forth, depending on itheir formulation and method of manufacture.

However, once formed, it is difficult to distinguish between foamed polymeric materials having different physical properties or between those made by different manufacturers. The manufacturer of the foam material used in particular goods may be identified by a swing tag or the like attached to the finished goods but it is not possible to identify the actual foam component as that of a particular manufacturer if, for example, a swing tag is removed or incorrectly applied.

In view of this and the variation in physical properties and grades of foamed polymeric material and the differences between foamed polymeric material D\99260008.6 2 produced by different manufacturers, a simple method of identification is required which does not need analysis of the chemical or physical properties of the foamed polymeric material.

In addition, in view of the competitive market, it is desirable for a manufacturer to distinguish its product from its competitors' products by providing a means for consumers and others in the supply chain to identify the foam component with its manufacturing origin, particularly if the product is of better .*.quality, or if it has certain qualities or characteristics.

The ability to readily identify the manufacturer of foam material also enables makers of furniture or goods that contain foam material to place orders more quickly during repair of the furniture or goods, thereby providing the customer with efficient service. It would also assist in ensuring that the same quality and type of foam is used in the repair.

Another commercial advantage of a means for the identification of a foamed polymeric material would be the ability of the manufacturer of the foam or manufacturers of goods containing the foam to authenticate the product. The producer of the foam could also track the diversion of its product if there was a means to identify the product. From another perspective, if a particular grade of foam is promoted as having a particular attribute and a consumer later complains that a product incorporating that foam does not display the promoted characteristic, the foam can readily be identified.

The present invention provides a means of identifying the manufacturer of foam material. It also provides a means of identifying a foam material.

D/01016015.2 3 Summary of the Invention In one aspect, the invention provides a method of producing a material which is distinguishable from other material of the same type, the material being formed from a liquid-phase precursor, including the step of incorporating throughout the liquid-phase precursor during manufacture a marker having readily detectable characteristics .(as herein defined). Preferably, the marker is a permanent (as herein defined) marker present in a quantity which does not substantially alter the physical properties of the material. More preferably, the marker is a fluorescent powder, and is added during manufacture such that a proportion of the powder forms spots in the finished material visible to the naked eye under UV light.

In a further aspect, the present invention provides a method of making a foam or foamed polymeric material which may be readily distinguished from other foamed polymeric material, which method includes incorporating into the material during manufacture and before foaming, a permanent marker having a readily detectable characteristic.

By "permanent" in this specification and the claims, we mean a marker S"which cannot be detached from the foamed polymeric material and is distributed throughout the foamed polymeric material, which will remain detectable for a .oe. 20 period of time but not necessarily indefinitely.

"readily detectable characteristic" in this specification and the claims, we mean a physical or chemical characteristic of the marker which enables its presence to be readily identified in a sample of the material. It will be apparent that "readily detectable" in this context means detectable by a person without oi S 25 specific technical training or scientific knowledge and using only instruments which are portable so that the characteristic can be determined in situ on site. It will also be apparent to one skilled in the art in view of the purpose of the invention that the A characteristic is not identifiable by normal unaided human senses, such as sight.

In another aspect, the invention provides a method of distinguishing a D/01016015.2 4 material from other material of the same type, the material being formed from a liquid-phase precursor, including the step of incorporating into the liquid-phase precursor during manufacture a marker having readily detectable characteristics (as herein defined), and subsequently detecting the marker with a detection means.

In yet another aspect, the invention provides a material having a selected marker impregnated therein for subsequent detection by a detection means to identify the source of the material.

Preferably, the material is a foamed polymer. Suitable foamed polymeric materials include foamed synthetic organic polymers such as foamed polyurethane polymers, foamed polyalkylene polymers, for example foamed polyethylene and foamed polypropylene, and foamed polystyrene. Most preferably, the foamed polymeric material is a foamed polyurethane polymer.

The marker selected for identification is preferably particulate in form and one that is detectable under ultra-violet (UV) light. Alternatively, the marker could be a radioactive compound. Further alternatively, the marker may have a contrasting colour to the material. In this case, the marker could be present in low quantities such that it is not easily visible to the naked eye. Markers which are ~....thermo-sensitive, for example, those that change in colour upon application of 20 heat or upon changes in surrounding temperatures may also be used. Markers comprising particles with magnetic detection characteristics can also be employed.

Other aspects and the advantages of the invention will be apparent from the detailed description of the invention hereinbelow. However, although the oa a., a: a D\99260008.6 invention will be described with reference to foamed polymers, the invention is not so limited, and can be applied to other types of material.

Brief description of the Figures A preferred embodiment of the invention will now be described by way of example only, in which:- Fig 1 is a photograph of a flexible foam having a marker detected by UV light.

Fig 2 is a photograph of a flexible foam having blue microsphere markers which are detectable under magnification.

10 Detailed description of the invention In Fig 1, a flexible, polyurethane foam (10) containing fluorescent powder (Brand name: UVITEX OB, Chemical Type: OPTICAL BRIGHTNER, Chemical composition: 2,5-thiophenediylbis (5-tert-butyl-1,3-benzoxazole)) is viewed under UV light. The three large and paler spots correspond to the fluorescent powder which was incorporated during manufacture of the foam. The fluorescent spots may arise from components which emit other colours, so long as there is contrast between the marker spots and the foam material to allow quick identification of the foam.

Other products that are UV responsive, or will fluoresce when exposed to the UV light, may be used in accordance with the invention.

The marker spots can vary in size, and are preferably 1-100 sq. mm in area. They can be randomly or evenly located on the surface, and also within the D\99260008.6 6 body, of the foam material. The distribution of the marker in the foam is random because of adding and mixing the marker with the various starting materials that make up the foam polymer during the foaming process.

Manufacture of Polyurethane Foams Polyurethane flexible or rigid foams may be produced by reacting a suitable polyol or mixture of polyols with di- or poly-isocyanates in the presence of stabilizers, cell control agents, blowing agents, catalysts and the like. The reaction is of a polyaddition type, which is strongly exothermic.

0* The polyols used in flexible foam production include diols or triols having a molecular weight of about 1000 to 7000. It is to be noted that both polyether polyurethanes and polyester polyurethanes may be manufactured and subsequently identified in accordance with the present invention.

The isocyanates used in flexible foam production are mostly based on toluene-diisocyanates and/or on methyl-diphenyl-diisocyanates in their various 15 monomeric or polymeric forms, or may be based on other aliphatic or aromatic isocyanates.

The stabilizer, cell control agent and surfactant compounds include but are not limited to various types of organo-siloxanes added in suitable amounts depending on the precise end properties required by the polyurethanes.

Blowing agents can be included so as to expand during the foaming and/or expansion stage of the reaction to fill the pores in the foam structure to make the product a cellular plastic.

Water, which is one example of a blowing agent, is generally present in 0\99260008.6 7 formulations at a concentration of from about 0.06 to 5.0 parts by weight (p.b.w) based upon 100 p.b.w. of the polyol or polyols. However, higher amounts of water may be used. The water/isocyanate reaction liberates carbon dioxide gas as a strongly exothermic reaction. This reaction contributes to the heat produced during the manufacture of the flexible polyurethane.

Low boiling halocarbons such as methylene chloride or other similar substances may act as auxiliary blowing agents. These evaporate at relatively low temperatures, e.g. 25 to 75 OC, and the vapours continue to expand as a result of the heat developed by the exothermic reaction, to fill the cells or pores of the fee**: 10 developing foam structure.

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Air may also be used as a nucleating agent and may be added by injecting it into the reaction mix to facilitate the formation of the cellular structure. The C reactant chemicals used in the formulation such as the actual polyols, catalysts, additives and the like are mixed in a predetermined ratio.

15 The density of the foam produced in a given polyol/isocyanate system is

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"C Ctypically from about 12 to 70 Kg/m 3 or more and is determined by the amount of blowing agent or agents present in the reaction mixture.

Other ingredients in a foam mix or system may include solid or liquid fillers, modifiers, cross linkers and other reactive or non-reactive components aimed at modifying the physical properties, combustion performance, weldability or other characteristics of the end product.

In general, the final physical properties of the resulting cellular plastic are determined by the nature and amount of reacting and non-reacting components present in the initial mixture. The final physical properties are generally reached D\99260008.6 8 after full cure, which may take 1 to 2 days after manufacture of foam.

The density of the cellular plastic is determined by the ratio and concentration of the chemical and/or physical blowing agents present in the reaction mix, as well as by the presence or absence of inert or reactive fillers, which may be present as either solids or liquids.

In particular, the final hardness of the resulting cellular plastic is *determined by the nature of the polyols, the stoichiometric ratio of the isocyanates S"°i to the polyol or polyols, the nature of the cross linking agent or agents if more than *a single agent is present, whether other reactive components and water are e* present, as well as whether liquid extenders or solid fillers are present in the reaction mix, including their quantity and in the case of solids their particle size distribution.

In addition to the chemical effects on the final physical properties of the foamed material as indicated above, the nature and amount of the various S 15 components also exert physical effects on the cellular plastic produced. In particular, the ultimate physical properties at any particular point within a foamed block are influenced by the precise position and location of that particular point within the mould or block, the size of the mould or block, the conditions under which the block was cured, such as, for example, the temperature and humidity of the atmosphere surrounding the block during the period of curing.

There are two basic techniques for producing polyurethane foam: Slabstock Production Large blocks of foam can be produced by either a batch process or a continuous process.

D\99260008.6 9 In a continuous process, 100 to 500 Kg/min of a liquid foam reaction mixture is laid on to a paper former on a moving conveyor and allowed to expand into a continuous block of, for example, 2 m width and 1 m in height, defined within two side walls and a base surface.

Further along the conveyor the continuous block of foam is cut into individual, suitably-sized blocks, of the order of from 1.5 to 2 m in length or more, and sometimes as long as 50 m.

These 2 m wide by 1 m high by 1.5 to 2 m (or more) long individual blocks require storage for a minimum of 16 to 24 hours to allow the heat generated by the exothermic reaction during curing to be safely dissipated, and for the *".curing process to reach completion before the blocks can be warehoused or processed into slabs, sheets, furniture components and so forth.

The continued curing and cooling of the slabstock foam traditionally takes place at the ambient temperature of the storage area. The blocks are set 15 apart from each other by a minimum distance (for example, of the order of a minimum 50mm) and during this initial period of 16-24 hours they are not, under usual circumstances, stacked on top of each other but rather are placed side by side or end to end in a slightly spaced apart relationship.

The blocks are stored spaced apart from each other so as to allow air to circulate between to provide more uniform cooling, and to prevent heat build up and thereby reducing the danger of auto-ignition of the freshly produced foam. During the initial 16 to 24 hours of storage, temperatures of up to about 100 OC to 175 OC are reached within the inside core of these blocks as a result of exothermic reactions during this post curing period.

This temperature is maintained for a further period of up to several hours, D\99260008.6 and the block then gradually cools down to ambient temperature. This process is slow, taking about 10 to 36 hours, because the foam by its nature is an excellent insulator of heat.

During this cure or post-cure period, secondary chemical reactions take place in the polyurethane structure such as, for example, residual isocyanate and amine/or urethane groups can react to form biuret and/or allophanate linkages or the like, all of which contribute to determining the :i final physical properties of the material.

~The nature of these reactions, including the nature and amount of any byproducts produced, and their reaction rate including the formation of reaction products which are incorporated into the polymer chains, are each dependent on the temperature and humidity conditions in the fresh foam storage room, but more particularly on the temperature and humidity conditions existing within the foam block itself. A practice in slabstock manufacture is to allow the block to cure by itself, thus creating a situation whereby the inner core of the foam block cures at a higher temperature than the portions near the outer walls of the block where heat is lost to the surrounding atmosphere.

The variation in the conditions and temperature of cure referred to above is in part responsible for the variation in hardness and related properties within a single block of foam, such as for example tensile strength, or the like.

As a result of the high inner core temperature, some types of foam may discolour in the inner core due to the effect of heat degradation. In some instances, the ambient temperature and humidity conditions within the fresh D\99260008.6 11 foam or hot block storage area at the stage of the curing process are not totally predictable, or at least are not accurately controllable, and may lead to further variations in properties of the cured polyurethane.

Even changes in atmospheric humidity within the fresh foam or "hot block" storage area are known to cause changes in foam properties e.g. a block of foam produced and cured under conditions of high humidity can exhibit softer properties lower in IFD hardness) than a foam made under identical conditions from the same ingredients but cured under conditions of 0 lower absolute humidity.

0* o* :ooo Moulding "o ~In this technique, the liquid foam reaction mixture is injected into a suitably constructed mould where the liquid is allowed to expand by foaming in the mould to form a solid block of foam of the desired shape. After demoulding, the final curing process takes place either at room temperature or in 15 temperature controllable ovens or tunnels at temperatures above ambient.

However, with some sizes and shapes of moulded, foampost-curing is required.

Preferably, foam or foamed polymeric materials are made in accordance with the invention using the slabstock production technique.

Preferably, the marker powder is added in a range of 0.00001 to 0.00100 parts by weight of the polyol present in the starting or reaction mixture of components used to produce a foam polymer. The powder may first be dispersed in, for example, 500 ml of dipropylene glycol which is then added to the remaining starting materials of the foam polymer. The fluorescent powder does not dissolve 0/01016015.2 12 in the reaction mixture but disperses throughout the mixture, producing finite areas of fluorescence or "spots" when viewed under UV light. The foam polymer may then be produced in accordance with the method described in AU 642131, the whole contents of which is incorporated herein by this reference. As would be apparent to one skilled in the art, the powder should desirably be added sufficiently quickly towards the end of the mixing process, so that the powder is not evenly dispersed throughout the material but is dispersed throughout the material as spots or clumps which will ultimately appear as fluorescent spots when the finished material is viewed under UV light.

The foam may, as indicated above, contain other desired components or additives normally found in conventional foam material such as stabilisers, cell control agents, blowing agents or surfactant compounds. It may also be coloured by using a dye or pigments during manufacture, provided that the colour of the foam does not substantially reduce the contrast between the foam and the fluorescent spots during detection. However, colour itself is not an adequate marker because it is easily copied and is readily visible to proposed copiers.

Markers that are especially preferred are those which are particulate and o have one or more detectable physical or chemical characteristics.

Other markers that may be selected to identify the material and/or 20 manufacturer include but are not limited to compounds which can be detected under infra-red light scanners or other scanners adapted to the unique characteristics of the selected marker.

A further example of a marker that can be used in accordance with

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the invention is coloured microspheres. Fig 2 is a photograph of a white flexible Sfoam containing a plurality of blue microspheres (represented by small dark spots) dispersed throughout. The microspheres will be visible when the foam is viewed D/01016015.2 12a through a low powered light microscope or magnifying glass. Other types of markers which are visible under magnification may be used, e.g. colour coded granules or particles. The microspheres are incorporated in the same manner as the impregnation of foam polymers with UV responsive markers.

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0 D\99260008.6 13 The invention can be applied to all types of foam material e.g. foam rubber, rigid foam plastics for structural use in boat construction, filtration or insulation systems or oil spill absorbents, and soft or flexible plastics or polymers for use in furniture items such as mattresses, sofas, chairs or cushions. The marked or "finger-printed" material may also be used as packaging or filler material.

Other embodiments may be contemplated by a person skilled in the art without departing from the central concept or scope of the invention. Further, it will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evidenced in the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

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