AU642131B2 - Effect of using chemical modifiers in the curing of polyurethane foams - Google Patents

Description

v PCr OPI DATE 01/05/90 AOJP DATE 07/06/90 APPLN. ID 43303 89 PCT NUMBER PCT/AU89/00426 Sml l INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 90/03997 CO8J 9/06, 9/08, 9/12 Al C08J 9/02, 9/22 (43) International Publication Date: 19 April 1990 (19.0490) (21) International Application Number: PCT/AU89/00426 (81) Designated States: AT, AT (European patent), AU, BB, BE (European patent), BF (OAPI patent), BG, BJ (OAPI (22) International Filing Date: 2 October 1989 (02.10,89) patent), BR, CF (OAPI patent), CG (OAPI patent), CH, CH (European patent), CM (OAPI patent), DE, DE (European patent), DK, FI, FR (European patent), GA Priority data: (OAPI patent), GB, GB (European patent), HU, IT (Eu- PJ 0848 7 October 1988 (07,10.88) AU ropean patent), JP, KP, KR, LK, LU, LU (European patent), MC, MG, ML (OAPI patent), MR (OAPI patent), MW, NL, NL (European patent), NO, RO, SD, SE, SE (71) Applicant (for all designated States except US): PACIFIC (European patent), SN (OAPI patent), SU, TD (OAPI DUNLOP LIMITED [AU/AU]; 500 Bourke Street, Mel- patent), TG (OAPI patent), US.

bourne, VIC 3000 (AU).

(72) Inventors; and Published Inventors/Applicants (for US only) WOOD, Allen [GB/ With international search report.

AU]; 4 Wallace Place, Mt. Martha, VIC 3934 With amended claims and statement.

JOUBERT, Michael, David [AU/AU]; 47 Roland Avenue, Strathmore, VIC 3041 (AU).

(74) Agent: McCORMACK, John; Griffith Hack Co., 601 St.

Kilda Road, Melbourne, VIC 3004 6 4 2 (54) Title: EFFECT OF USING CHEMICAL MODIFIERS IN THE CURING OF POLYURETHANE FOAMS (57) Abstract An improved method and process for making a foam material, preferably a polyurethane foam material, more preferably a flexible foam material in which an additional additive is incorporated into the liquid foamable mixture. The additive is capable of undergoing or entering into an endothermic reaction or is capable of forming or decomposing into one or more gaseous products at a preselected temperature or over a preselected range of temperatures. The endothermic reaction or decomposition or production of gaseous product beneficially influences the properties of the foamed material when forming or when formed. The properties of the foam material produced by the improved method and process are more uniform, reproducible and controllable than the corresponding properties of foams produced by conventional formulations.

1 RECEIVED 11 JUL 1990 PCr/A 0 0 1 2 6 1 EFFECT OF USING CHEMICAL MODIFIERS IN THE CURING OF POLYURETHANE FOAMS The present invention relates in general to polyurethane foams including both flexible foams and rigid foams and to methods for their manufacture. In particular, the present invention relates to improvements in the curing and post curing steps of the method used in the manufacture of foamed polyurethanes.

In particular, the present invention finds application in the formulation of a foamable mixture for making foam material with more controllable, reproducible and/or uniform properties.

ISUBSTUTE SHUT

I

1 RECEIVED I JUL PCr/AU. S 0 0 426 In general polyurethane flexible or rigid foams are produced by reacting a suitable polyol or mixture of polyols with di- or polyisocyanates in the presence of stabilizers, cell control agents, blowing agents, catalysts and the like.

The reaction is of a polyaddition type and is strongly exothermic.

The polyols used in flexible foam production are generally diols or triols having a molecular weight of about 1000 to 7000. It is to be noted that the present invention may be used in the manufacture of both polyether polyurethanes and polyester polyurethanes.

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

The stablilizer/cell control agent/surfactant compounds are generally various types of organo-siloxanes added in suitable amounts depending on the precise end properties required by the polyurethanes.

Blowing agents are 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.

SUSTITUT SflE£T| I,/r-n u RECEIVED 11 JUL 9O 3- 0 0 4 26 Water which is one example of a blowing agent is generally present in formulations at a concentration of from about 0.06 to 5.0 parts by weight based upon 100 p.b.w. of the polyol or polyols. However, it is to be noted that higher amounts pf, water may be used. The water/isocyanate reaction will liberate carbon dioxide gas in a strongly exothermic reaction. This reaction contribute-s to the heat produced during the manufacture of the flexible polyurethane.

Low boiling halo-carbons such as monofluoro-trichloromethane and/or methylene chloride or other similar substances may act'as auxiliary blowing agents.

These evaporate at relatively low temperatures, e.g. 25 to C, 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 developing foam structure.

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 reactant chemicals used in the formulation such as the actual reactants, catalysts, additives and the like ate mixed in a predetermined ratio.

The density of the foam produced in a given polyol/isocyanate system is typically from about 12 to kg/m 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 amounts of reacting and non-reacting components present in the initial mi'ture. The final physical properties are generally reached after full cure which may take 1 to 2 days after manufacture of foam.

SSUBSTITUTE SHEET Pc'/AU. 9 0 0 426 S RECEIVED 13 DEC 1989 -4 In particular, 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 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 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 effects indicated above due to the nature and.amount of the various ingredients which are in essence chemical effects on the cellular plastic there is at any particular point within the cellular plastic produced the effects which result from essentially physical effects. In particular the ultimate physical properties at any particular point within the foamed block are influenced by the precise position and location of that particular point within the mouldingor block, the size of the moulding or block, the conditions under whic the block was cured, such as for example, the temperature and humidity of the atmosphere surrounding the block during the period of curing.

Briefly, there are two basic techniques for producing polyurethane foam: The first technique is Slabstock Production Large blocks of foam can be produced by either, a batch process or continuously.

In a typical 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 say for example 2m width and Im in height, defined within two side walls and a base surface.

2 «SUBSTITUTE SHEET RECEIVED 1 JUL 1990 2 C r #'J7 9 0 0 4 5 Further along the conveyor the continuous block of foam is cut into individual, suitably sized blocks, say typically, of the order of from 1.5 to 2m in length or more, and sometimes as long as These 2m wide by im high by 1.5 to 2m or more long individual blocks require storage for a minimum of 16 to 24 hours to allow the heat generated by the exothRrmic 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 or whatever.

During the initial 16 to 24 hours of storage all of the foam blocks are laid down individually in an attempt to allow the heat which develops within each sufficient time to dissipate uniformly. Temperatures of up to about 1000 to- 175 0 C are reached within the inside core of these blocks as a result of exothermic reactions during this post curing period. However, the heat developed by the exothermic reactions is not uniformly distributed throughout the block since the central portions of the block which are relatively more insulated by the bulk of the block develop a much higher temperature than the peripheral portions which are less well insulated by being surrounded with less foam material and accordingly, the dissipation of heat is uneven.

The other technique is Moulding In this technique, the liquid foam reaction mixture is injected into a suitably constructed enclosure the mould where the liquid is allowed to expand by foaming such that the shape of 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 of in temperature controllable ovens or tunnels at temperatures above ambient. However, with some sizes and shapes of moulded foam post-curing is required.

SUBSTITUTE SHEiT i i s I i RECEIVED 1 JUL 1990 FecI, B3/0A 04 26 6 However, with some sizes and shapes of moulded foam post-curing is required.

It is to be noted that the present invention is more suitable in the process of slabstock production rather than in the process of producing shaped foamed articles by the moulding process. However, the present invention can be useful and also finds application in treating moulded pieces as well.

The post curing of slabstock foams takes place traditionally at the ambient temperature of the storage area. The blocks are set apart from each other by a minimum distance (say of the order of a minimum 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 in 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 thus, reduce the danger of auto-iginition of the freshly produced foam.

Typically, the cure or post-cure of the freshly manufactured and cut blocks from the slabstock production line takes place in a fresh foam or "hot block storage" room, where the inner core or inner portion of each block reaches a temperature of about 100° to 175 C in from up to 200 seconds after formation, maintains this, temperature for a further period of up to several hours and 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 heats.

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 final physical properties of the material.

SUB STITUTi .6JTr RECEIVED 11 J UL 1990 P tm 8 9 0 O4 2 7 0 I1 M The nature of these reactions,including the nature and amount of any byproducts produced, and their reaction rates 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 fuam storage room but more particularly on the temperature and humidity conditions existing within the foam block itself. The current practice in slabstock manufacture is to allow the block to cure by itself thus reating a situation whereby the inner core of the foam block niulrs 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 tend to discolour in the inner core due to the effect of heat degradation.

More often than not, the ambient temperature and humidity conditions within the fresh foam or hot block storage area at-_this stage of the curing process are not totally predictable or at least are not accurately controllable which leads 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 lower absolute humidity.

Therefore, it is an aim of the present invention to providea method which attempts to produce a more controllable, uniform and/or reproducible foam material by modifying the environment around and within the cells of the foamed material. Typically, the properties which are more controlled are hardness, density, tensile strength, elongation, compression set and the like.

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According to the present invention there is provided a method of producing a polyurethane foam from a mixture of liquid foam reactants, the method comprising incorporating a solid additive into the mixture in an amount in a range from 2 to 30 pph of polyol prestnt in the mixture, the additive being capable of endothermic decomposition or endothermic physical change after the foam has substantially formed and at a temperature below that which would be reached in the absence of the additive.

The properties of the foamed material are beneficially influencei' by reducing the maximum temperature reached during the curing process.

The additive material may include materials which decompose or give up their water of crystallization or breakdown endothermically when heated. Additive materials may decompose or give up their water of crystallization at temperatures between 10 and 200 0 C but preferably at a temperature of at least about 80 0 C. Typical examples of such materials include the following: 20 Ammonium carbonate which decomposes to ammonia and carbon dioxide at a temperature of 58 0

C.

Aluminium sulphate A1 2 (S0 4 3 18H 2 0 at 86.5 0

C;

S

S

RECEIVED 1 1 JUL 1990 PcT/AU 89/ 0 0 4 26 9 Calcium phosphate, (monobasic) CaH4(PO 4 2

.H

2 0 at 1000C; Calcium sulphate CaSO 4 .2H20 losing 1 H20 at 128 0 C,the balance H20) at 163 0

C;

Ferrous ammonium sulphate Fe(NH4) 2

(SO

4 2 .6H20 at 100 to 110°C; Potassium sodium tartate KNaC 4

H

4 0 6 4H 2 0, melting range 70-80 0 C, liberating water of crystallization at 140 C; Sodium borate Na 2

B

4 0 7 .10H 2 0 at 75°C to 3200C; Sodium carbonate, monohydrate Na 2

CO

3

.H

2 0 at 109 C; Aluminium ammonium sulphate Al2(NH 4 2

(SO

4 4 .24H20, loses 20 H20 at 120°C.

Aluminium potassium sulphate A1 2

K

2

(SO

4 4 24H20, loses 18H20 at 64.5 0

C.

Calcium acetate Ca(C 2 H30 2 2

.H

2 0, decomposes on heating to produce gaseous products.

Calcium acetyl salicylate Ca(CH3COO.C6H 4

COO)

2 .2H20, aqueous solution unstable and decomposes to give off gaseous products.

Calcium chloride CaCl 2 CaCl 2 .2H 2 0, CaCl 2 .6H20, loses 4H20 at 30 0 C, 6H20 at 2000C.

Calcium citrate Ca 3 (C6H 5 0 7 2 .4H 2 0, loses water at 100-1209C.

Calcium salicylate Ca(C7H 5 0 3 2 .2H20, loses water at 120 0

C.

Silica gel when heated gives off its absorbed water.

Sodium sulphate decahydrate Na 2

SO

4 .10H 2 0, at 100 0

C

(melting point 33°C).

Other additive materials typically include the following: gas saturated adsorptive carbons, zeolites, molecular sieves, and the like, polypropylene, polyethylene, and other plastics, calcium stearate, and similar materials which are endothermic due to their melting properties in the required temperature range.

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RECEIVED 1 1 JUL 1990 1 U PCT/AU 3 9 00 4 26 Typically, the additive is included in the reaction mixture at the time of formulation of the liquid mixture in addition to the usual, typical or conventional materials that are incorporated in the reaction mixture.

The products of the decomposition of the additive normally include a gas or mixture of gases or a vapour or mixture of vapours. The gaseous decomposition products influence the curing step of the solid urethane polymeric structure.

The influence of the vapour or gases may be selectively localised. The inner core of a freshly produced block will stay for longer periods of time at higher temperatures, say at from 120 to 165 0 C. Peripheral areas of the same block will stay for shorter periods at the high temperature level or will be at lower temperature levels. Therefore, the rate and amount of decomposition of the additive and the decomposition processes will take place to different degrees and varying amounts depending upon precisely where inside the block the additive is located and whether the additive is located internally within the cell or in the polymeric materials forming the matrix in which the cells are located whether the locatic i is intra or intercellular.

Alternatively, the block may be surrounded by insulation so that the heat distribution is more uniform, and accordingly so is the cooling-down process which allows the decomposition products to develop as fully as possible, because variation in the cooling rate of different parts of the block will not be as great and the overall rate of cooling will be slowed down compared to the situation where the block is uninsulated.

Typically, the additive is a hydrated mineral salt, giving up its water of crystallization at elevated temperatures. The developing water vapour from the decomposition of, say-for example, hydrated calcium sulphate CaSO 4 .2H 2 0, would occupy the cells of the freshly produced cellular polyurethane thereby providing a controlled humidity condition for curing.

RECEIVED 1 JUL 1990 Pc/A 09/004-26 In clxtain instances such endothermic chemical reaction, i.e. the loss of water of crystallization, will reduce the maximum exotherm temperature of the foaming material, thus reducing the danger of auto-ignition of the freshly produced foam block in some cases which is another advantage of the present invention.

Typically the additive is a compound like the ammonium salts, such as for example ammonium carbonate or the ammonium acetates. Typically, the additive is any such compound which decomposes at about 60 to 180 0 C, typically 100 to 1700C, more typically 120 to 165°C, often giving up vapours or gases which can influence the secondary chemical reactions which take place during the curing period immediately following the foam formation.

The additive can be organic or inorganic. The additive may sublime at an elevated temperature to give off a gas.

Alternatively, the additive may undergo a change from solid to liquid to gas. Therefore, the final physical properties of the polyurethane foam polymer as well as the temperatures developed during the foaming and/or curing step, such as from the time the exothermic reaction begins and thereafter, can be directly influenced by the presence pf the vapour'or gas from the additive when inside the cells of the foamed blocks, or can be influenced by the endothermic nature of the change in phase, e.g. melting of the additive.

Although not wishing to be bound by the following theory, it is thought that in some cases the advantages of the present invention may be brought about by free isocyanate groups present in the foaming material or in the freshly produced foam reacting with the additive, particularly water vapour given off by any decomposition or loss of water of crystallization. The foamed material may then cool down faster because there are no or very little free SSUBSTITUTE

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RECEIVED 1 JUL 1990 12- 9/00426 12 0 4 2 isocyanate groups left unreacted to enter into further reactions which conventionally prolong the ing of the foamed material to produce heat.

Also, it is thought that water vapour resulting from loss of water of crystallization contributes to reducing the hardness of the foamed material in the centre of the foam, which balances the effect of atmospheric moisture in the outer portions of the block. This effect can be utilized to reduce or eliminate the use of chlorofluorocarbon or methylene chloride to achieve a given type of foam which will be described by way of example later in this specification.

The amount of the additives included in the reaction mixture may vary widely depending on the particular additive chosen and the end result sought. Typical ranges are from pph to 170 pph expressed as parts per hundred based on the total amount of polyol present in the reaction mixture.

More typically, the amounts range from .2 to 100 pph, even more typically 2 to 30 pph.

Typical materials useful as additives in the present invention include mineral hydrates, organo metallic hydrates and dessicant materials also adsorptive carbons, molecular sieves, zeolites, polyethylene, polypropylene, calcium stearata etc. which are useful due to being endothermic because of their melting properties rather than due to their chemical breakdown and the attendant production of gaseous products. Although these materials do not decompose under heating they can give off water vapour or other gases at elevated temperatures. A particularly preferred material is gypsum G75 which is supplied by Commercial Minerals Limited of Camberwell, Victoria and which has the following specifications.

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RECEIVED I 1 UL 1990 ETr/An 8 9 0 04 26 13 Typical Chemical Analysis Calcium Sulphate CaSO 4 2H20 97.5% Calcium Carbonate CaCO 3 0.3% Combined Iron and Aluminium Oxides 0.37% Sodium Chloride NaCl 0.03% Acid Insolubles 1.46% Sizing Analysis Residue at 7 Microns: Less than Mean Particle Diameter: 3.3 microns Surface Area 7900 cm 2 /gm Typical Physical Properties Brightness 84% Oil Absorption 31 ml/100gm Specific Gravity 2.3 pH 8.3 Bulk Density (Tapped) 1.08 gm/cc Bulk Density (Loose) 0.64 gm/cc Another aspect of the present invention relates to the incorporation of additive materials which may either enter into endothermic reactions with other materials already present in the formulation or may undergo a change which is endothermic. Any material added to the foaming mixture which undergoes or enters into an endothermic reaction will reduce the amount of exothermic heat generated.

The present invention will now be described by way of example with reference to the accompanying drawings in which; Figure 1 is a schematic representation of a foam block showing the position of representative test samples taken from the block upon which performance tests were conducted; SUBSTITUTE SHEET PCT/AJU. 9 0 0 4 2 6 RECEIVED 1 3 DEC 198 14 Figure 2 is a plot of hardness as a function of vertical position of the selected test sample within the block; Figure 3 is a plot'of hardness as a function of horizontal position of the selected test sample within the block; Figure 4 is a plot of exotherm temperature as a function of time for various locations of the test samples, within the block; Figure 5 is a plot of the internal foam temperature developed within the block as a function of time for varying quantities of additives; Figure 6 is a plot of the internal foam temperature developed within the block as a function of time for different additives; Figure 7 is a plot of density as a function of vertical position of the test sample within the block; and Figure 8 is a plot of hardness as a function of vertical position of the test sample within the block.

In Figure 1 there is shown schematically a block of foam generally denoted by A, from which representative test samples are taken generally denoted by b, and tested for various properties such as hardness, density and the like.

The' location of the test samples are denoted by one of the reference numerals 1 to 9 in a horizontal plane or grid and by one of the reference numerals 1 to 14 in a vertical plane or column. it is to be noted that none of the samples tested are taken from the extreme edges of the block but rather the block is skinned by removing one or more layers from the block prior to subdividing the block into the test samples. The block is skinned to remove the extreme outer layers because the properties possessed by the extreme outer layer are very atypical of the block as a whole and are hence discarded so as not to produce spurious results in any of the tests conducted on the samples.

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a A I N PCT/L.U 3 9 0 U 4 1 RECEIVED 1 3 DEC 1989 15 Generally, as shown in Figure 1, the vertical positions are broadly divided into 3 main areas which are denoted as top, middle, or bottom of the block. Although each of the 9 horizontal positions is. associated with 14 vertical positions, in practice each horizontal position is usually only associated with 3 vertical positions, making a choice of 27 different samples. By selectively taking the samples from the choice of 27 positions it is possible to gain an overall picture of the block. If more detailed information is required because each of the 9 horizontal positions can be subdivided into the 14 vertical samples a more detailed picture of any one area can be obtained. In practice however, it is usual to select only 3 vertical samples for each horizontal positions.

In Figure 2 there is shown a plot of hardness expressed in newtons as a function of the 14 vertical positions for a column located at each of two horizontal positions, both with and without additives; one of the horizontal positions being located at or towards an edge whilst the other is located at the centre. The abbreviations "EXP" refers to an experimental batch of foam having the additive in this case 4.0 pph of G75, whereas the abbreviation "REF" refers to a standard foam block formulation for producing a conventional foam block without additive.

Clearly from Figure 2 both of the experimental foam blocks containing 4.0 pph additive are considerably softer than the corresponding blocks made to the conventional formulation.

The hardness of the EXP blocks being of the order of 85 to 105N whereas the hardness of the REF blocks is from 125 to 145N. Additionally, the EXP blocks exhibit more homogeneous properties with less variation than do the REF blocks. The test samples at vertical positions 6 to 10 of the REF blocks, particularly the REF block at the centre exhibits a greater variation from about 130N to about 145N when compared to the more even hardness obtained in the EXP blocks of about 94+1.N.

Thus, in this example it can be readily seen that the inclusion of the additive produces a foam with more uniform "U ,SUpSTI'UTE SHEET p 5' u PCT/MAJ 39 0 426 RECEIVED 1 3 DEC 1989 16 properties than is achieved without the inclusion of the additive and thus the final properties of the foam are more controllable. It also reduces the foam hardness relative to the REF block.

Figure 3 illustrates the difference in hardness obtained between the experimental foam, EXP, containing additive and the reference foam, REF, not containing the additive for each of the 9 horizontal positions at the same vertical level. From the top vertical position, a test sample was taken from each of the 9 horizontal positions which are number 1 through to 9 as per the positions illustrated in Figure 1. Similarly, 9 test samples were taken from the middle vertical level and tested. Also, 9 test samples were taken from the bottom vertical position and tested. The 27 test samples in all were tested for hardness and the results plotted in Figure 3 in groups of threes. The results from the EXP block were compared to the results from the REF block.

Clearly, .the variation of hardness within a single vertical level of 9 test samples, was greater for the REF block than for the EXP block. The variation of the REF block being generally of the order of between about 10 and 15N whereas the variation of the EXP block was about SN. In addition, the EXPblock was. appreciably softer. Moreover,' the variation between adjacent positions of the REF block, particularly between edge locations and centre locations, was considerably greater than the variation between corresponding adjacent positions in the EXP block. This is particularly illustrated in the values of hardness obtained at positions 4, 5 and 6 of the block for the middle and bottom test samples of the REF block which vary by about 13N when compared to the values obtained at the corresponding positions of the EXP block which vary only by about 3N. Additionally, it can be seen that the variation between samples taken at the same horizontal position but at different vertical positions of the one block was considerably greater for the REF block than for the EXP block. Thus, again ST^ I 3SUBSTITUTE

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RECEIVED 1 1 JUL 1990 PCr/in C /o 00 4 17 the inclusion of the additive clearly produces a foam block having less variation in hardness through both its thickness and length or width.

Figure 4 illustrates a temperature-time profile of the cooling of the foam block during post cure for two samples of each of the REF block and EXP block in which a first sample was taken at the edge of the block while the other sample was taken at the centre of the block. The temperature-time profile clearly indicates that the inclusion of the additive results in a lower maximum temperature being attained during the exothermic reaction, about 150 0 C for the REF block at the edge as compared to about 125°C for the EXP block at the edge, and faster rate of cooling as in the case of the centre test sample where both initial temperatures were about 150°C but the REF block took 600 minutes to cool to 120°C whereas the EXP block took about 400 minutes to cool to 120 0

C.

Figure 5 is a time-temperature profile for the exothermic reaction during the manufacture of the foam block for different formulations containing differing amounts of additives. The additive was and was added in amounts of 0 pph (corresponding to a cohventional formulation) 5, 10, 20, 40, 60 pph. With the exception of the formulation containing 50 pph the temperature in all other cases was less than the temperature of the conventional formulation. This clearly indicates that once the additive has been added .above a critical threshold the heat generated by the reaction is somehow modified so as not to reach such a high level. Typically, it is thought that the modification is probably cause by the endothermic nature of the breakdown of the additive. The reduction in maximum exotherm temperature clearly aids in providing a foam or more uniform properties as was illustrated in Figure 3.

(f ^t_

T/

RECEIVED 1 1 J U L 1990 pCer/A 9 0 0 4 26 18 It also provides the opportunity to use formulations which would otherwise generate unsafe temperatures with the danger of auto-ignition. This concept can be used to modify formulations for the given density foam, so that no auxiliary blowing agent (CFC, methylene chloride) is required. An example illustrating the effect of incorporating an additive and omitting the auxiliary blowing agent will be described later in more detail.

This is particularly so when the rate of cooling of the block with the formulation containing 40 and 60 pph is considered since their rate of cooling is greater than the rate of cooling of blocks having an amount of additive less than 20 pph 0, 5 and pph).

Figure 6 illustrates the modifying effect on the maximum temperature of additives other than The other additives used are magnesium sulphate, sodium tetraborate and sodium orthophosphate as indicated. All three of these other additives reduce the maximum temperature at 5.0 pph levels of additions. Clearly, the observed beneficial effect of the present invention is apparent with a range of additives.

Figure 7 illustrates the difference in density of each of the test samples at position 1 through to 14 of one column of test samples similar to that of Figure 2 in relation to hardness for a different overall formulation than that used in Figure 2. Although the variation of density between the test samples of the EXP block is about the same as that of the REF block, the REF block is somewhat less dense and accordingly, shows a flattening of the density profile.

Figure 8 illustrates a hardness profile for a different formulation as a function of vertical position within a column of test samples.

I SUBSTITUTE SHEET RECEIVED 1 1 JUL 1990 PCT/AII 8 9 00 4 26 19 Examples Improvement in the desired properties of the foam, such as a more uniform distribution of density and/or hardness from the top to the bottom of the foam block has been achieved in a number of cases.

Such improvements of the gradients is claimed to be due to the release of water vapour from the additives on reaching temperatures corresponding to the liberation of the water of crystallization whereby this takes place in the centre, higher temperature sections of the block, and balances a similar process taking place in the outer portions of the block which are subject to reaction with atmospheric moisture, and which do not reach the dehydration temperature of the additives.

SUBSTITUTE SHEET PCr/NaQ 0 0 4 2 0 RECEIVED 13 DEC. 1989 20 Example 1 Foam Grade: Nominal Density (kg/rn 3 Nominal Hardness, IF 40 (Newtons): Additive: Gypsum Concentration: 0.2 par Method of Processing: Laborat No. of Samples: A30-120 120

F

-4a

J

G75 *Supplied by Commercial Minerals ts per 100 polyol ory hand batch in 38cm 2box 3 each.

Density 'in kg/n3 Range Avetagei Std. Deviation Results Reference (untreated foam) 30.6 -34.1(3.5) 32.03 1.834 Sample (treated foam) 30.4-32.2(1.8) 31.07 0.987

IF

4 0 Hardness in NWwtons .I Range 127-148(21) Average 137.3 Std. Deviation 10.501- 1 1216.7 5.03 Comment: Hardness deviation reduced.

SUBSTITUTE SHEET PCTZAI1 S 0 0 4 2 6 RECEIVED 13 DEC 1989 21 Example 2 Foam Grade: HR36-130 High Resilience Type Foam 3 Nominal.Density (kg/rn 36 Nominal Hardness, 'IF 40 (Newtons): 130 Additive: Gypsum Concentration: 0.15 pphp Method iof Processing: Laboratory handmix No. of Samples: 3 each.

Density in kg/n 3 Range Average Std. Deviation Results Reference (untreated foam) 37.2-38.6(1.4) 37.80 0.721 Sample (treated foam) 36.7-38.1(1.4) 37.23 0.757

IF

40 Hardness in Newtons Range- 150-155(5) Average 152.00 Std. Deviation 2.646 146-148(2) 147.33 Comment: Hardness deviation reduced.

$,VT

j 'JDSTITUTE SHEET P~Cr/ fL'3 9 604 2 6 RECEIVED~ 3 DEC -1989- 22 Example 3 Foam Grade: Nominal Density (kg/rn 3 Nominal Hardness,, IF 0 (Newtons): A27- 150 157 Additive: Concentration: Method' of Processing: No. of Samples: Gypsum 0. 2 pphp Laboratory handmix 3 each.

Density in kg/rn 3 Range Average Std. Deviation Results Reference (untreated foam) 27.3-31.5(4.2) 28.93 2.250 Sample.

(treated foam) 27.4-30.*5(3.1) 28.60 1.664

IF

40 Hardness in Newtons Range15-8(0 Average 1L63.67 Std. Deviation 16.073 157-182 170.33 12.583 Comment: Density and hardness deviation reduced.

SUBSTITUTE SHEE1T PvCTKrtfM

RECEIVED

0/0 42 3 D EC 1989 23 Example 4 Foam Grade: Nominal Density (kg/n 3 Nominal Hardness, IF 40 (Newtons): A24-150 24 150 Additive: Concentration: Method 'of Processing: No. of Samples: Gypsum 0.5 pphp Laboratory handmix 5 each.

Density in kg/rn Range Average Std. Deviation Results Reference (untreated foam) 24.5-27.0(2.5) 25.44 0.96 Sample (treeated foam) 24.4;-27.0(2.6) 25..38 1.01 IF 40 Hardness in Newtons Range 168-190(22) Average 176.8 Std. Deviation 10.13 167-188(1).

177.4 8.38 Comment: Hardness deviation reduced.

SUB3STITUTE SHEET PCr/AI 3 9 0 4 2 6 RECEIVE1Y 24 3 DEC'1989 Example Foam Grade: Nominal Density (kg/m3): Nominal Hardness, IF 40 (Newtons): A30-120(repeat tests) 120 Additive: Concentration: Method of Processing: No. of Samples: Gypsum 0.2, 1.0, 3.0 pphp Handmix 4 of each set Density in kg/m 3 Range Average Std. Deviation Density in kg/m3 Range Average Std. Deviation Density in kg/m 3 Range Average Std. Deviation Results Reference (untreated foam) 30.4-32.9(2.5) 31.18 .1.184 30.4-32.9(2.5) 31.18 1.184 30.4-32.9(2.5) 31.18 1.184 Sample (treated foam) 0.2 pphp 30.1-31.8(1.7) 30.78 0.741 1.0 pphp 3066-32.6(2.0) 31.38 0.866 3.0 pphp 30.4-32.1(1.7) 31.03 0.759

IF

40 Hardness in Newtons SRange 123-161(38) Average 135.5 Std. Deviation 17.3

IF

40 Hardness in Newtons Range 123-161(38) Average 135.5 Std. Deviation 17.3

IF

40 Hardness in Newtons Range 123-161(38) Average 135.5 Std. Deviation 17.3 0.2 pphp 123-136(13) 131.8 .5.97 S1.0 pphp 127-133(6) 131.0 2.7 3.0 pphp 102-115(13) 107.0 5.72 Comment: Reduced deviation in hardness and density.

S.STI TUT[NE -I 6' PC /AM 39

RECEIVED

/00 42 6 3 E C 1989 25 Example 6 Foam Grade: Nominal Density (kg/rn )3 Nominal Hardness, IF 40 (yewtons): A27 -150 27 150 Additive: Concentration: Method 'of Processing: No. of Samp les: Gypsum 0.5 pphp and 1.0 pphp Laboratory handmix 4 each.

Density in kg/rn 3 Range Average Std. Deviation Density in kg/rn 3 Range Average Std. Deviation Results Reference (untreated foam) 27.4-29.0(1;0) 27.'95 0.755 27. 4-29.0(1.6) 27.95 0.755 Sample (treated foam) 0.5 pphp 27.3-28.6(l.3) 27.8.5 0.580 1.0 pphp 27.3-29.0(1.7) 27.95 0.742 0.5 pphp 157-170(13) 162.5 6.137 1.0 pphp 160-171(11) 166.0 4.546 IF0Hardness in Newtons Range 152-167(15) Average 160.3 Std. Deviation 6.652

IF

40 Hardness in Newtons Range 152-167(15) Average 160.3 Std. Deviation 6.652 Comment: Deviation reduced.

jcS~) ~y~ i ~'c K 'vZ 0~ SiJBS- 11!J;E SHfET PCT/A. 3 9 0 0 4 2 6 RECEIVED~ 1 3 DEC 1989 -26 Example 7 Foam Grade: Nominal Density (kg/rn 3 Nominal Hardness, 1F 40 (Newtons): A27-150 27 150 Additive: Concentration: Method-'of Processing: No. of Samples: Gypsum 0.2 pphp and 2.0 pphp Hand mix 45cm 2 x58crn high 8 each.

Density in kg/rn 3 Range *Average Std. Deviation Denity in kg/rn 3 Range Average Std. Deviation Results Reference (untreated. foam) 28.2 0.26 27.8-28.6(0.8)- 28.2 0.26 Sample (treated foam) 0.2 pphp, 27.4-29.1(1.7) 27.9 0. 57 2.0 pphp 28.0-29.2 28.4 0.39 0.2 pphp 174-185(11) 180 4.3

IF

40 Hardness in Newtons Range 178-192(14) Average 189 Std. Deviation 5.3 SUBSTITUTE SKEET POT/Al Ur 9 o 0 4 2 6 RECEIVED) .3 D EC 1989 27 0 1 Example 8 Foam Grade: Nominal Density (kg/rn Nominal Hardness, IF 40 Newtons): Additive: Sodium Concentration: 0.3 pph Method'of Poesn:45cm 2 h No. of Samples: 8 each.

H35-160 135-37 150-180 phosphate, Na 3 P0 4 12H 2 0 p andbatch, 60-65 cm high Density in kg/rn 3 *Range Average Std. DeViation Results *Reference (untreated foam) 36.8 0.40 Sample (treated foam) 35.9-36,.9 0) 36.4 0.31 IF 40 Hardness in.Newtons Range 164-181(17) Average 173 Std. Deviation 7.5 157-175(18) 167.4 S'UBSTrIITUTESIT r C PCT/AXI 3 9 0 0 4 2 0 RECEIVED~ 3 DEC 1989 28 Example 9

N

Foam Grace: 3 Nominal Density (kg/rn) 5 Nominal Hardness, IF 40 (Newtons): Additive: Gypsum Concentration: 1.0 pphj Method of Processing: Maxfoam (2.08m No. of Samples: 20 each AZI150b 27 150 pmachine, full size bloc Iks wqide, 1.66m high, 1.52m long) Results Reference 3 (untreated foam) Density in kg/rn All 20 Samples Range 26.2-28.6(2.4) Average 27.6 Std. Deviation 0.700 Density in kg/rn 18 Samples Without Top Bottom Range .26.2-28.2(2.0) Average* 2.7.5 Std. Deviation 0.674 IF 40 Hardness in Newtons All 20 Samples Range 126-172(46) Average 157 Std. Deviation 11.75 Hardness in Newtons 18 Samples Without Top Bottom Range 136-172(36) Average 160 Std. Deviation 8.86 Sample (treated foam) 20 Samples 26.3-28.4(2.1) 27.3 0.567 18 Samples 26.3-27.8(1.5) 27.2 0.489 20 Samples 133-168(35) 156 10.18 i8 Samples..- 139-168(29) 159 7.82

IF

4 0 SUBSTITUTE SNEET pcTZW8 9 g 0 4 'L 0 RECEIVED 3 D EC 1989 29 Example Foam Grade: Nominal Density (kg/rn 3 Nominal Hardness, IF 40 (Ne~wtons): A17-80 17 Additive: Concentration: Method of.Processing: No. of Samples: Gypsum 0.5 pphp Maxfoam block machine 20 ea~ch Density in kg/rn 3 Range Average Std. Deviation Results Reference (untreated foam) 16.5-17.4(9.9) 1:7.~0 0.25 Sample (treated foam) 16.5-17.1(0.6) 16.8 0.20 IF 40 Hardness in Newtons Range 75-94(9) Average 87.5 Std. Deviation 5.26 76-92(6) 86.7 4.44, Comments: and 8).

-Two graphs attached to this example (see Figures 7 SUBSTITUTE SKiET r

AA.

RECEIVED 3 E C 1989 Example 1.1 ELIMINATION OF CFC 11 IN A LOW DENSITY FOAM Formulation using Gypsum G-75 Laboratory Handzuixes 1 2 3 Reference Gypsum G-75 Same as 2 No. CFC but without G-

I

a Polyol Niax 16-5 6 OMU 56, Kwt. 3000 100.00 100.00 100 .00 (b) Silicone BF.2370 Total water Stannous octoate *Amine Catalyst CFC 11 Gypsum G-75 T.D.I. 80:20 Density Kg/rn 3 Hardness IF 40 Newtons Exotherm, Temperature OC 1.20 4.55 0.22 0.19 5.00 0 60.8 20.1 135 162 1.50 6.0,0 0.40 0.05 0 30.00 68.00 21.3 132 142 1.50 6.00 0.25 0.05 0 0 68.,00 17.3 153 175 Amine Catalyst 3 Parts (03% triethylene diamine, 67% dipropylene glycol) 2 Parts (70% Bis-dimethylaminoethyl-ether, dipropylene~ glycol) FiTI TU T E S F' T Pcrv 3 9 0 0 4 2 S- RECEIVED 3 DEC 1989 Supplied by Union Carbide Australia Ltd.

Supplied by Th. Goldschmidt AG.

In Example 11, is shown a comparison of 3 batches of foam denoted as Batches 1, 2 and 3. Batch 1 corresponds to a standard reference formulation which includes the auxiliary blowing agent but no additive. The auxiliary agent is CFCll which is a chlorofluorohydrocarbon. Batch 2 corresponds to a formulation falling within the scope of the present invention and has an additive material incorporated but no auxiliary blowing agent. Batch 3 contains no additive and no auxiliary agent.

As can be seen from the properties obtained for Batches 1 and 2, particularly the properties relating to density and hardness which are indicator properties giving an indication of the overall properties of the foam, the properties of Batch 2 corresponds closely to the properties of Batch 1. Thus, the incorporation of the-additive contributes to the final properties which are more reproducible and controllable even when the auxiliary agent is omitted from the formulation.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within its spirit and scope.

4SUBSTITUTE SHEET

Claims (11)

1. A method of producing a polyurethane foam from a mixture of liquid foam reactants, the method comprising incorporating a solid additive into the mixture in an amount in a range from 2 to 30 pph of polyol present in the mixture, the additive being capable of endothermic decomposition or endothermic physical change after the foam has substantially formed and at a temperature below that which would be reached in the absence of the additive.

2. A method according to claim 1 wherein the additive decomposes by loss of water of crystallization.

3. A method according to claim 1 wherein the additive decomposes by loss of carbon dioxide.

4. A method according to claim 2 wherein the additive dehydrates at a temperature in the range between 60 and 180 0 C.

5. A method according to claim 1 wherein the additive is selected from the group consisting of ammonium 9carbonate, aluminium sulphate, calcium phosphate, calcium S 25 sulphate, ferrous ammonium sulphate, potassium sodium tartrate, sodium borate, sodium carbonate, sodium phosphate, aluminium ammonium sulphate, aluminium potassium sulphate, calcium acetate, calcium acetyl salicylate, calcium chloride, calcium citrate, calcium salicylate, silica gel and sodium sulphate.

6. A method according to any one of the preceding claims wherein the polyurethane foam formed is rigid or T7< flexible.

7. A method according to claim 1 wherein the additive is one or more of the following: adsorptive carbon, zeolite and a molecular sieve.

8. A method according to the additive is gypsum.

9. A method according to wherein the additive decomposes range from 60 to 180 0 C. claim 1 or claim 2 wherein either claim 1 or claim 3 at a temperature in the A method according to any one of claims 1 to 3 wherein the additive decomposes at a temperature in the range from 100 to 170 0 C. S. S. S S S S *s S S S. S 5*55 S S S a.r

11. A method according to wherein the additive decomposes range from 120 to 165 0 C. any one of claims 1 at a temperature in to 3 the

12. A method according to any one of the preceding claims wherein the mixture of liquid foam reactants includes polyols and the additive is incorporated into the mixture in an amount in the range from 0.05 pph to 170 pph based on the total amount of polyol present in the reaction 25 mixture. DATED THIS 9TH DAY OF AUGUST 1993 PACIFIC DUNLOP LIMITED By its Patent Attorneys: GRIFFITH HACK CO Fellows Institute of Patent Attorneys of Australia.