CA1052050A - Cellular moulded articles produced from synthetic resin emulsion - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

This invention relates to a new process for producing moulded articles with an open-pore cellular structure and a water content of not more than 14% by volume, preferably 0-5% by volume, which comprises polymerising or curing and simultaneously shaping a water-in-oil emulsion containing from 5 to 30% by weight of an inorganic, flame-retarding barrier-layer forming component in powder form, and subsequently drying out the excess water.

Description

~ This invention relates to a new process for the production of shaped articles with a cellular structure.
Plastics are the preferred materials for the manufacture of shaped articles in all kinds of fields.
Plastics articles are easily produced in large numbers, and present a number of advantages with respect to their strength. However, the inflammability and combustibility of these plastics, which are in themselves suited to the 0 use in question, often stand in the way of this use. Thus, for example, in materials which are used as building materials or interior furnishings for rooms, not only is - their inflammability in itself important, but also their behaviour in a fire in the presence of increasing radiant heat, their extinguishability, and their heat conductivity, particularly at high temperature~ abo~e 600~C are ~f importance. Therefore there has been no shortage of attempts to make such combustible plastics non-inflammable. For preference, halogen, phosphorus and antimony compounds 0 are used for this. It has however been shown that in a number of plastics, many of these flame-retarding components work their way to the surface of the shaped part and are removed from there by mechanical effects. In this way the plastic is constantly losing flame-retarding components, .' ' ~

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with consequent increase in the combustibility of the plastic.
Particularly in foam plastics, not inconsiderable difficulties arise in adapting the products, and shaped articles made from them, to the re~uirements which are imposed on flame-proof plastics, particularly when used as building materials.
According to a process known from German Offen-legungsschrift 1 544 857, non-combustible sound-proofing building elements are manufactured by polymerising a water-in-oil emulsion of styrene and/or methacrylic acid ester and/or vinyl ester with a minimum water content of 2~%. Non-inflammability is obtained by the fact that the water of the emulsion stays, to a large extent, in the building element, and is held there for a long period. For this reason it is recommended that the outer surfaces of the elements be covered with metal foil or an alloy foil made of metal/paper/plastic. The water can also be kept in the elements made from the emulsion by addition of hydrophilic compounds.
The possibility is also referred to of lastingly reducing the inflammability of such elements by additionally incorporating flame-retarding components such as e.g. phosphorus and halogen compounds. According to this lO5Z050 known process, the combustibility of the elements thereby produced is substantially reduced and, in the event of the elements igniting, the temperature only rises slowly. For comparison, a plate 5.5 mm S thick, made of an emulsion with unsaturated polyester and having a water content of about 80% by weight, coated with aluminium foil 0.1 mm thick and heated with a blow-lamp flame (1150C) on one side, has, after 3 minutes, a temperature of 90C on the other sidè of the plate, whereas with a corresponding asbestos sheet of the same - thickness a temperature of 450C is measured after only 2-minutes.
Certainly, the aluminium foil initially protects the plastic sheet - from the effect of the heat. However, it cannot be avoided that the water slowly escapes from the shaped parts produced in accordance with this previously known process. Conneceed with this are a gradual shrinkage and dlstortion of the elements, and also a loss of flame-proofing, corresponding to the quantity of -water lost.
Dehydrated cured emulsions or emulsion foams as they will be called hereafter, cannot be adequately protected by the usual means from the effècts of flames, on account of their very large surface area.
; Therefore possibilities have been sought of flame-proofing emulsion foams in such a way that the shaped parts produced from them resist even high burning temperatures, . . ~

and that this protective effect does not subside as the density of the emulsion foam decreases.
In British Patent Specificiation No. 1458203 (Application No, 53652/73) I describe and claim a process for producing shaped articles with a cellular structure which comprises shaping and curing an emulsion comprising from 25 to 90 parts by weight of water dispersed in from 75 to 10 parts by we~ght of a liquid synthetic resin-monomer mixture comprising styrene and/or a methacrylic ; 10 or acrylic acid ester and a copolymerisable unsaturated . polyester or copolymer of styrene and butadiene, the emulsion having a dispersion level which is in the characteristic range (as therein defined) prior to commencement of curing and the curing being effected at a i .~ 15 rate.whereby the emulsion gels before commencement of disintegration of the emulsion, The expr-ession . "characteristic range is used in British Patent Specification No, 1458203 to define a dispersion level range extending from a lower limit at which the water-in-oil emulsion can be cured to a shaped article whose volume amounts to at least 90/O of the volume occupied by the emulsion prior to commencement of curing to an upper limit at which the water-~ .
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i ~ in-oil emulsion can be cured whilst maintaining at least 90% of the emulsion vo~ume prior to commencement of curing to a shaped article with a continuous fine-porous structure which loses at least 20% of the weight of the water contained in the cured emulsion from a sample with a ratio of surface to volume of 1,17:1 when dried at a temperature of 23C and a relative humidity of 60% for 24 hours.
According to the present invention I now provide a process for producing a shaped article with a cellular : 10 structure and a water content of not more than 14% by volume which comprises shaping and curing an emulsion comprising from 25 to 90 parts by weight of water dispersed in from 75 to 10 parts by weight of a liquid synthetic resin-monomer mixture comprising styrene and/or a methacrylic or acrylic acid ester and a copolymerisable unsaturated , : polyester or copolymer of styrene and butadiene and there-after drying to provide a water content of not more than 14% by volume in the shaped article thus produced; the :
said emulsion containing from 5 to 30% by weight of an , inorganic flame-retarding component (as herein defined) in powder form with an average particle size of not m~ e than 50~ in diameter (the percentage being based on the total :'' , .
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lOSZ050 . weight of emulsion), the emulsion having a dispersion level which is in the characteristic range (as herein defined) prior to commencement of curing and the curing being effected at a rate whereby the emulsion gels before ,, 5 commencement of disintegration of the emulsion, : The characteristic range is used herein in precisely ; the same sense as in British Patent Specification No, 1458203, It extends from a dispersion level at which dispersion has just commenced and is minimal up to a level at which there is an onset of stable dispersion formation i,e, formation of an emulsion which will not change its phase structure upon subsequent curing and which does not decompose as a result of phase change, The characteristic range of the dispersion level following the increasing dispersion of the dispersed phase can be regarded as being capable of subdivision into a lower, medium and upper portion, If the dispersion level of the emulsion is set to a value which is in the lower portion of the characteristic range, by curing of this emulsion shaped articles are obtained whose base or outer surfaces have distributed over them a closed and non-porous polymer-isation layer whilst the remaining portions of the shaped .
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article form a coarse to fine cellular structure. These shaped a.rticles have a sandwich character, whereby the thickness.of the closed layer and the cell diameter of the cellular layer decrease with increasing dispersion level of the emulsion, Inasfar as the cells of the cellular layerare open-celled the water, optionally after opening the closed dense polymerisation layer, can be removed by suction or dried out, If the dispersion level of the emulsion is set to a value which lies in the middLe portion of the characteristic range shaped articles are obtained having a medium to fine structured core surrounded completely by a thin dense polymer layer. Within this portion of the characteristic range the skin-like layer becomes thinner and finally permeable with increasing dispersion level of the emulsion. In the same way with increasing dispersion level of the emulsion the cellular structure of the core becomes.finer, From these shaped articles the water contained in the cells of the core can be removed despite the presence of the closed, thin, outer layer by suction . 20 by opening this layer or can be expelled by drying, provided that the cells of the core are open, On setting the disp-ersion level to a value which lies in the upper portion of ., .
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the characteristic range shaped articles are obtained whose surface has no resin deposits and which overall consists of a very uniform fine cellular structure with open and/or closed cells, With increasing dispersion level of the dispersion ~- 5 phase in the emulsiDn the diameter of the cells of the shaped ~; articles produced from the particular emulsion becomes increasingly smaller. On further increasing the dispersion level the emulsion passes into the state of absolute stability and in this state can be completely cured. The lO onset of this dispersion state occurs at the upper extremity ~ of the characteristic range as herein defined. Inasfar r as the emulsion is present in the state of absolute stability its curing leads to shaped articles which eitherdo not give off the water or only give it off with 15 difficulty, Water is removed from the cured emulsion preferably by drying at a temperature of from 15 to 500C. Drying -~ can of course also be effected if desired at temperatures of over 500C.
., -The monomer content of the synthetic resin-monomer mixture used in the process according to the invention comprisesstyrene and/or an ester of methacrylic or acrylic ., .

, ~13 ~oszo~o acid such as for example methyl methacrylate, ethyl methacrylate, ethylene glycol methacrylate, 1,4-but-2-ene dimethacrylate, cyclohexyl methacrylate, ethyl acrylate or 1,2-propanediol diacrylate The mixture may also if desired , contain additional monomers, e,g. a nitrile such as for example acrylonitrile t The monomer component of the mixture can if necessary serve as the solvent or diluent for the synthetic resin portion This resin portion can be a high molecular .. 10 weight unsaturated polyester or a copolymer of styrene and butadiene which is copolymerisable with the monomer or monomer mixtu~e Particularly suitable are unsaturated polyesters which are obtained by condensation of dihydric alcohols, for example ethanediol, 1,2-propandiol, 1,3-` 15 propandiol, diethylene glycol, 1-allyl-2,3-hydroxypropandiol and unsaturated a~-ethylenically unsaturated dicarboxylic acids, for example maleic acid and fumaric acid In addition the unsaturated polyesters can also contain di-. and polyvalent carboxylic acids, for example endomethylene ` 20 tetrahydrophthalic acid, tetrahydrophthalic acid, phthalic .
: acid, succinic acid, adipic acid, propionic acid, benzene tricarboxylic ~cid and benzene tetracarboxylic acid, and 'i~' .
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also other low grade alcohols such as benzyl alcohol, 1,2-di(allyloxy)-3-propanolglycerol, pentaerythritol, as well as hydroxycarboxylic acids, e g 4-hydroxymethyl-cyclohexane carboxylic acid The use of these substances . 5 for expanded resin products is described in United States ~eissue Patent 27,444, German DOS 2,046,575 and German D~S 1,024,564, 1,067,210 and 1,081,222. In conjunction with self-emulsifying polyesters it is also possible to use epoxide compounds with more than one epoxide bond as the polymerisable phase, as indicated in German DOS
1,495,843 - It is particularly advantageous to use a mixture ~~ of styrene and methyl methacrylate in the weight ratio 4 to 4:1 as monomer together with an unsaturated polyester . 15 copolymerisable therewith In addition it is also possible to add to the emulsion polymers of high molecular weight which do not copolymerise with the monomer These are preferably polymers of styrene, vinyl chloride, esters - of methacrylic acid and optionally unsaturated polyesters which are copolymerised with monomers, for example with styrene or methyi methacrylate, . In order to form an emulsion of the water-in-oil ,.......... .

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~OSZ050 type, an emulsifying agent with molecules consisting of hydrophobic and hydrophilic portions is preferably used, Such emulsifying agents may be used individually or in admixture, Emulsifying agents which partially separate in the ~- monomer portion of the water-in-oil emulsion in the presence of water have proved to be particularly suitable, The stability of such emulsifying agents can be proved by ,~ a simple test, For this purpose, 5 to 10% by weight (based on the total weight of the emulsion) of the emulsifying agent or mixture of emulsifying agents to be tested are ~`~ dissolved in the monomers of the process, A few drops of water are added to about 10 cc of this solution, In the '-; case of particularly effective emulsifying agents the introduction of the water leads to a visible separation, Examples of low molecular weight water-in-oil emulsifying agents are esters of higher fatty acids with polyhydric alcohols, amides of higher fatty acids and salts of alkylsulphonic acids, Frum the very large number of ' 20 high molecular weight compounds particularly suitable are `~ polymers or polycondensates which are completely or almost completely water-insoluble and which containing hydrophilic .:

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-105;~050 groups such as for example carboxyl, carboxylate, carboxamide and hydroxyl groups, ester or ether groupings, amino, ammonium, sulphonic acid and/or sulphoxide groups Such emulsifying agents are for example described in German Patent 1,301,511 Copolymers with an acid number between 8 and 12 which consist of units of an ethylenically-unsaturated carboxylic acid, for example acrylic acid, ; and styrene, and wherein the free carboxyl groups are wholly or partially neutralised with organic or inorganic bases, can be used with equal success. It is also possible to use polymers or copolymers of styrene, methyl methacrylate or vinyl acetate as the emulsifying agent ,. if these polymers or copolymers are produced in emulsion polymerisation processes in the presence of persulphates ' 15 and consequently contain sulphonic acid groups Saturated and unsaturated polyesters can also be effective as emulsifying agents, particularly if they are partly or completely saponified with alkali~ or if they contain an adequate number of free carboxyl groups These emulsifying agents ~re for example described in detail in German DAS 1,199,982 or German Patent ~pecification 1,267,845, These can be the same polyesters as are also ~ .
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, used as the resin component of the resin - monomer mixture, It is also possible to use graft copolymers -which are produced in the presence of polyalkylene oxides from styrene and which are described for example in German . 5 DAS 1,169,671 as emulsifiers, It is also possible to use film-forming polymers, e,g, cyclised rubber or copolymers . of vinyl compounds with a gr~up having 8 C-atoms described : in German DAS 1,148,382 as emulsifying agents. It is also possible to use as emulsifying agents hydrophobic polymerisation products of organic compounds which contain 0.5 to 60%, preferably 28 to 55%, by weight of oxyethylene . groups as hydrophilic components, Preferably the hydrophobic portion of these emulsifying agents can be . composed of polyoxypropyLene and must then have a ~: 15 molecular weight of over 600, Also copolymers with a total molecular weight of above 800 which contain 90 to - 20% by weight of polyoxypropylene glycol and 10 to 80%
by weight of polyoxyethylene glycol are suitable emulsifying agentssuch as are known from German DOS 1,495,227. -Further suitable emulsifying agents are described in German DOS 2,046,575 and 1,928,026. The effectiveness 'oi the en~ls iiyin6 a~ents soluble in the organic phas e ~' ".
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can be increased by water-soluble l~w molecular weight organic compounds which contain both a hydrophilic and - a hydrophobic proportion Compounds of this type are in particular alcohols, organic acids, ethers, ketones and wetting agents It is understood that the above-indicated emulsifying agents can be used individually or in mixture The quantity of the èmulsifying agent or mixture of emulsifying agents which is advantageously u~ed is adjusted according to the desired dispersion level of the emulsion and is preferably in a range from 0 05 to l~/o by weight (based on the total weight of the emulsion) 25 to 90 parts by weight of water are then emulsified in 75 to 10 parts by weight of this polymerisable mixture. In order to disperse the water in the organic phase conventional stirrers, - 15 dissolvers or similar apparatus can be used.
In order to cure the emulsion, curing catalysts are conveniently added These curing catalysts can be water soluble, e.g alkali, formaldehyde, sulphoxylates, per-sulphates, hydrogen peroxide, sodium hydrogen sulphite and 20 cobalt chloride However, it is also~possible to use catalysts such as benzoyl peroxide, lauroyl peroxide, ethyl methyl ketone peroxide, cyclohexanone peroxide, .''' :

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- azodiisobutyryl nitrile, N,N-diisopropyl-p-toluidine, tertiary amines, such as dimethylparatoluidine, dimethyl-or diethylaniline and cobalt naphthenate, which are soluble in the polymerisable phase In some cases it can be advantageous to use in addition to a water soluble catalyst one which is soluble in the polymerising phase. These catalytically active substances are with advantage a~ded in quantities of 0 1 to 10% based on the total weight of the emulsion Furthermore wetting agents, inhibitors (e g.
4-ethyl-pyrocatechol, 3-methyl-pyrocatechol, tertiary butyl .
' pyrocatechol, toluquinol, quinol, 2,5-di-tert.-butylquinoneand p-benzoquinone), cross-linking compounds, softeners, ` fillers and dyes may if desired be added to the emulsion prior to use.-` 15 The process of the invention provides shaped ~ -articles with a cellular structure which is predominantly - open-pored in character, that is with a major part of the cells of the structure being open-pored The cells are preferably as fine as possible with an average cell - 20 diameter of not more than 50~, and ad~antageously less than 20~, in which thefLame-retarding component is contained, `
either dissolved or evenly distributed as a fine-particulate '' ' , .

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- solid The use of fire-retarding components in accordance with the invention makes it possible to produce shaped articles which are stable even at temperatures above 800C
' thus preventing the spread of fire The expression "flame retarding component" is ~ used herein to define a component of the emulsion which i serves to retard burning or to provide resistance to burning in shaped articles produced therefrom The flame-retarding components used in accordance with the present invention preferably have an average particle size of not more than 20~.
As flame-retarding components, there may for example . be used, according to the invention, inorganic compounds which split off water at high temperature, for example ~ 15.~ water glass (in the form of sodium ~ potassium di- and . tri- silicates), calcium sulphate dihydrate, silicates such as magnesium silicate and aluminium silicate, boron compounds such as borax, aluminium hydroxide, asbestos, . and crystallinesalts which contain water of crystallisation which is released at higher temperatures Equally good flame-proofing is obtained with non-com.bustible inorganic : substances which split off carbon dioxide when they ignite, : 5q e,g. calcium carbonate (convenien~ly used as chalk) and sodium bicarbonate, These flame-retarding components can be introduced into the emulsion in the form of an aqueous solution or as powdery solids, There may also be used compounds, e.g. para-. formaldehyde, urea, phosphates, dicyandiamide and phosphoric acid esters of pentaerythritol, which at higher temperatures ~- (220-3000C) expand to provide flame-retarding properties, Such flame-retarding components can additionally be applied as lacquers or solutions for impregnating the finished . shaped articles, whereas the other flame-retarding components to be used according to the invention are only added to th emulsion before hardening.
Even with small quantities of the flame-retarding 15 components mentioned above, e,g, from 5 to 2~/o by weight based on the weight of the emulsion (i,e, the total weight ;; of the emulsion including any further ingredients), outstanding flame-proofing has been obtained even at high temperatures above 1000C, : 20 The shaped articles produced according to the invention also have the advantage that in the event of fire they are easily extinguished.with water and scarcely : - ' .

; distort under the action of high temperatures Such a resistance to the effects of burning could not be predicted since, with the same flame-retarding components in compact non-foamed resins, no such effect is achieved.
If desired, at least part of the flame-retarding component can be provided by a substance serving also as - a filler, for example perlite, chalk or asbestos The emulsions used in the process according to the invention may also if desired contain a filler component in addition to, or instead of, such flame-retarding components.
Fibrous and/or particulate filler materials, if desired of coarse particle size, may be used Such materials which have proved suitable include plastics and foams which do not dissolve in the emulsion or do not disintegrate through dissolution or expansion, in the form of tiny, optionally expandable particles, hollow spheres, solid spheres, and fillers with, optionally, larger particle sizes, made, e g. from polyurethanes, melamine resins, urea resins, formaldehyde resins, phenol resins, epoxy resins, polyamides, PVC, polyvinylidene chloride, poly-acrylonitrile and polymethacrylate, or from expanded inorganic materials, e g., glass, clay, perlite, vermiculite, .. : .

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lOSZ050 slag and pumice Heavy aggregates such as quartz, grit and asbestos are~also suitable as fille~s.. Where the filler is in the form of fibres, the mechanical properties, particularly the rigidity, of the shaped articles produced according ~ to the invention may be substantially improved, Flame-retarding components serving as fillers and/or ~. additional fillers may be used in combination as desired in order to vary the density and mechanical properties, ` 10 such as rigidity under pressure and inflexibility, of the '~ shaped articles produced according to the invention - The fillers which can be used may be of such a course particle size (e g 10-30mm in diameter), that the water-in-oil emulsion, which already contains the inorganic flame-retarding components, can fill the spaces between ¦~ the particles, while the emulsion can also contain filler particles which are finely ground and able to slide (0 05-2mm in diameter) In general the fillers conveniently have a particle size from 0 05 to 30mm, For the completion of the process according to the invention, it is moreover advantageous to remove the water within a short time, Investigations have shown that ~, ,. .
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.'~f, ,,. ,. 105Z.050 the final shrinkage measurement. in emulsion foams is only reached when 75-85% of the water used has been removed, A high water content in the shaped articles produced according to the invention can affect the good insulating effect of the porous material against heat, and therefore also the stability of this material at higher temperatures.
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; Emulsion water remaining in the product or escaping very slowly indicates that the water must be diffusing out of closed cells. This very condition, through irregular drying, leads a) to distortion and b), under the action of flames, to a strong tendency to crack. Openings are caused through which the flames penetrate.
Predominantly sealed-pore materials barely absorb any moisture after water has diffused out. In open-pored emulsion foams the residual moisture which is advantageous in flame-proofing can, taking into consideration the r; humldity of the air, be put in and retained by the co-use of hygroscopic materials and materials which contain water ~- in a phy~i~ally bound state, but which 1s given off at high temperatures. Under the effect of heat, the steam can escape from the open pores, without pressure building up in them. Open-pored foams can be filled with wate~r-during a fire or when there is danger of fire, so that additional extinguishing and flame-proofing effects are obtained. The water quickly dries out again afterwards without causing any damage. Also, impregnation with flame-retarding components can be performed.
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~ According to the process of the invention, the shaped ;~ articles obtained have a structure such that unobstructed drying can proceed and the water is . .

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not compelled to diffuse out through cell walls, i.e. a structure which is predominantly open-celled is ensured. This can be tested by the rapidity of the drying process itself, exactly like testing the permeability of liquids and gases, but also usefully, by testing the absorption speed of liquids, i.e. in the drop-absorption test. For the shaped articles produced according to the invention, it is therefore preferred that they have the smallest possible water content after drying, advantageously not more than 0-5% by volume, which amount is mostly present because of the humidity of the air itself.
The openness of the pores of the end product produced from a water-in-oil emulsion is controlled by suitable adjustment of the dispersion level of the emulsion as hereinbefore explained.
This adjustment of the dispersion level is advantageously effected by the use of emulsifying agents and by controlling the mechanical distribution via the stirrer, by means of its number of turns and the stirring time of the emulsion.
In this way the required openness of the pores and thus degree of dryness in the desired time after curing is obtained. At the same time the mechanica~ properties dependent on the volume of the pores, the fineness of structure, and the proportions of open and closed . .

lOSZ050 cells are also ad~usted.
The required dispersion level can be ascertained in a simple way by viscosity measurement. The viscosity of the emulsion is related to its stability during curing, on the one hand, and to the dehydration properties of the cured product, on the other hand, as is disclosed in British Patent Specification No. 145~203 (British Patent Application 53652/73).
With about six test experiments, a curve can be ascertained from which one can clearly see the dispersion level to which the emulsion must be adjusted in order to dehydrate the finished shaped article in a short time after curing.
For this, about six samples of the water-in-oil emulsions, of increasing viscosity, which can be set by increasing the number of turns, the stirring time or the temperature, but also by means of the emulsifying agents, are cured in otherwise similar starting conditions. From these six cured samples, the weight when wet, and the de-hydration by drying at a temperature of 23C, with ventilation, are determined. The process can also be shortened by determining the weight loss shortly after curing and after the water has been suction filtered off under reduced pressure. If the weight loss or water loss as a lOSZ050 percentage is related to the viscosity, a curve results from which the most suitable viscosity can be ascertained for yielding, on the one hand, a sufficiently solid, and on the other hand, a fast-drying product.
The ratio of open to closed pores can also easily be ascertained, as mentioned above, by the speed and quantity of the uptake of liquids (water, alcohol) in sample articles.
It must be borne in mind that adding flame-retarding :~
components and fillers can substantially alter the nature of a :
~ .; water-in-oil emulsion. An emulsion which, after curing, - ~.
- -~ has.. à.suf.ficient-drying speed or openness of pore~s, can 1~. lead to a virtually sealed cellular system by the-addition .. of fillers. The`adiustm~nt ~ ~ e... di ~ersi~.a ~ ~

: therefore, to be performed, if possible,-with.théJe addit ~ .

In the following illustration the chang.es in drying speed, depending on viscosity, are shown with the help of .

;: a graphic represent~tion. It can be clearly seen that the .

properties of the cured products are pre-determined :; ~
` with the adjustment of the dispersion-level. . -~`
~-. . The values graphically shown in the Figure are obtained with a water-in-oil emulsion, consisting of 45 parts by weight -of an unsaturated polyester ca~t resin and 55 parts by weight : of water. In the experiments the .

viscosity was altered each time and the sample piece was dehydrated by suction filtering. The water 1098, per cent, ascertained after suction filtering was correlated with viscosity before curing. The change in water loss, in relation to the viscosity, is connected with the stability of the emulsion during curing. The openness of the pores can be adjusted via the dispersion level, as can clearly be seen, and as described in British Patent Specification No. 1458203 (British Patent Application 53652/73). The dispersion level is set at a favourable drying range between 1500 and 200cP, since, in this range, the mechanical values increase again.
The shaped articles manufactured according to the new process attain, at low densities (from about 0.15 g/cm3), flame , resistance and mechanical properties which would not have been at all expected.
Thus, for example, a 4 cm thick~ sheet, produced according to the invention, and made from an emulsion with a water content of 60%, a styrene-modified polyester resin and 34% by volume of expanded glass (1-5mm particle size), has a density after drying of 0.38. In a-comparison -test with a corresponding material made, according to a previously-known process, from expanded polystyrene and cement, and a material made from polyester foam and expanded glass, .:

lOSZ050 the following solidity values result:

Material Density Rigidity Infle~ibility Heat-con-g/c cm under2pressure kp/cm ductivity ; kp/cm number Foamed poly- 0.3 3 2 0.1 styrene/cement 0.5 15 4 0.15 Foamed poly-ester/expanded glass 0.37 32.5 - 0.6 Emulsion foam/
expanded glass 0;37 60 30 0.047 . ~
When the previously-mentioned emulsion foam sheet, placed vertically, is directly exposed ~o flames from a butane burner, which produces a temperature of 1600G on the upper .
surface of the sheet, a temperature of 140C is not measured with a thermocouple element on the back of the sheet until-after 55 minutes. It should here be pointed out that the flllers used for economical reasons favour heat conduction, but to the not inconsiderable detriment of flame-proofing.
It is believed that the favourable results of the emulsion foam produced according to the invention must obviously be explained by the fact that owing~to th~ s~ructural fineness of the cured emulsion, with the escape of water an excelleht temperature insulation is obtained, which scarcely changes, even at higher temperatures.

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2-7 -The slight alteration of the heat conduction number (kcal/m.h. C) as the temperature rises can be seen from the following Table:

Emulsion foam without 0.047 0.048 0.049 filler, density 0.3 Emulsion foam with filler 0.0475 0.0485 0.05 (expanded mineral), Resin : filler = 1 : 1, Density 0.35 ~ .
Thus it can be seen that the alteration in the heat con-duction number is smaller than is known for conventional . insulation foams, such as those made from polystyrene, for example.
~- For a better characterisation of the properties under the - effects of flames, comparative experiments are subsequently ~, ` . -:
performed, in which the flame-retarding components to be used according to the invention are added to compact resins and emulsion foams. As has already been mentioned, the proportion of open cells in the cured product is pre-determined, in performing the process of the invention by ~ , ~
adjusting the dispersion level, and the presence of a maj~r proportion of open cells makes it possible for 75-85X of the water introduced with the emulsion to be removed, without complications, in , . . .

the shortest possible time. Thus the open cellular structure which is obviously necessary for flame-proofing the products according to the invention is obtained and, in the shaped article produced according to the invention, the adjustment of the residual water to a quantity of preferably between 0 and 5%, to a maximum of 14% calculated on the volume, is possible taking into account the air humidity and the addition of hygroscopic materials and additives which contain physically bound water.
The advantageous residual water content varies according to the density and combustibility of the materials and the filler content. It is of advanta~ge if, in performing the process of the invention, one takes into account the emulsifying agents and procedures which lead to open-pored foams and which are described in U.S. Reissue~Patent 27,444,- U.S. Patent

3,734,867 and in Belgian Patents 785,091 and 74I,308.
In these publications, however, the procedures which lead to a small w~ter residue in the dried product are not given.
In the following investigations, therefore, the adjustment of the small water content in the end product is first undertaken via the dispersion level, using three recipes for emulsion foams as starting materials.
; In the following table (in which all proportions are by - weight unless otherwise stated) the composition of the formula , ~ .

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for the emulsion foams is stated, and, with the given viscosity, the value is ascertained which guarantees a corresponding dehydration and openness of the pores of the product containing the introduced flame-retarding components.
The composition of the samples varies only in the ~ quantity of water added to the emulsion, in the viscosity, ç and the various flame-retarding components tested in the burning test. The preparation of the samples is performed in known manner. The polymerisable portions of the formula and the ~- additive which is soluble in them - without accelerators -are added, with water, to the water-in-oil emulsion. The flame-retarding component is added to the complete water-in-cil emulsion, to the water, or to the resin as desired and finally the peroxide catalyst and the fillers are stirred~in.
The emulsion is poured into a 7 x 7 x 3 cm polyethylene container and cured. Before the casting is removed, the weight when wet is determined and the sample is dried at 23 C until it reaches a constant weight. The residual water content is determined and the burning test is performed. In the burning test (see Table 2) the sample is clamped Ln a vertical position and exposed to a butane 1 burner flame at right angles producing a temperature of 1600C in the light blue centre of the flame. The centre flame at 1600C is directed onto~the surface of the ., ' .

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experimental body in such a way that, at this spot, a temperature of approx. 1600C occurs over a surface of about 15-20 mm in diameter. On the back of the sample part, in a borehole set at a distance of 10 mm from the centre of the flame, the temperature is followed for a period of 5 minutes, by means of a thermocouple element. In addition, after removal of the charred parts, the depth in the centre of the burnt-out depression caused by burning is measured.

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-~ 10 5Z~DS~D
In Table 1, the abbreviations, explained as follows, are used In this explanation, the percentages referred to are by weight:

UP = Unsaturated l Commercial product made from polyester resins maleic and phthalic acid anhydride and propylene glycol;
styrene content 35%, viscos~ty 650-lO0 cP at 20C, acid number below 30 = U P 1 2. Commercial polyester ca~ resin based on HET acid;
; Type lllO according to DIN 14946, chlorine content 27%, maximum acid number 30, styrene content-25% = U P 2 Monomers 1. Styrene = St .~ 2 Methyl methacrylate = M M A

Peroxides 1. 50% Benzoyl peroxide = B P --Accelerator 1, 50% Dimethyl-p-toluidine - D M T

Inhibitor 1 "C 10" (Manufacturer Ak~d Chemie GmbH) ~ Emulsifier 1 Pluronic 123 (Manufacturer ;~ Wyandott;"Pluronic" is a ` registered Trade Mark):
. Condensation product made from .~ propylene and ethylene-glycol = -In Table l, the symbol "X" indicates that the figure is the same as that given for the immediately ~ preceding experiment, `: .
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- 10 5Z~D5~D
sThe following observations apply to the experiments (i.e. example referred to in the preceding Tables 1 and 2.

Examples l - 5 are for purposes of comparison; Examples 6 - 19 illustrate the invention :-Example 1 The sample contains no flame-retarding substance of any kind. The sample begins to burn all over immediately after the fl~me has been applied, and after only 1 minute a hole 3.5 cm wide has been burnt through the sample. The experiment is interrupted. The sample has lost three quarters of its weight.

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Example 2 - The sample was produced with a chlorinated commercial polyester resin, chlorine-paraffin content 20%, with the addition of 5% of antimony trioxide. After a little over 2 minutes the sample is burnt through.

Example 3-5 The behaviour of the materials using fillers-of coarse particle size is demonstrated, namely-expanded c~ay (diameter 2-3 mm) quartz ~diameter 2-3 mm) and boron silicate glass (diameter 1 mm).

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~ - 36 -,: . :

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'' iOSZ050 These samples are not satisfactory either, since they start to burn over the whole surface, and after a short time the maximum temperature of 100C is attained on the back.
A clear improvement, however, was then obtained with perlite and chalk, whereby, for perlite, a mixture of very fine parts, of particle diameter approx. 40~, and ` coarser parts up to 2 mm in diameter, was used.

:
Examples 3-8 ~ -- Received the additives under the following considerations. It is taken as a premise that, in flame- -proofing, the ratio of distribution of the flame-retarding ~;
materials and the combustible substances is-of importance. ~ ;
I The additions in the aforementioned Examples 3-8 ~-~, were therefore made in proportions by volume, namely, ~t for each part by volume of emulsion, two parts by volume ~ ~ -of filler were added. The samples 3-5, with coarse fillers, ~`~
immediately began to burn over their whole surface, and on the back, a temperature of 100C was reached after a short ; time.
The samples 6, 7 and 8, provided with finer fillers, - namely perlite and chalk, are clearly distinguished from them.

' lOSZ050 Here, a significantly more effective flame-prooflng can already be ascertained. The mixture of fine and coarser-particled perlite already fulfills the conditions necessary for the performance of the process, and so does the chalk.
In Examples 9-13, the flame-proofing qualities of various silicates and borax is proved. It is shown that the temperature measured on the back rises slowly and moderately.
The depth of the burnt-out depression is between 5 and 9 mm.
Over the burnt centre, spreads a more or less solid insulating layer, which, after removal, reveals the undamaged state of the material which was treated with the flame.
Examples 14-17 are performed with increasing concentrations of flame-retarding agents and increased pore volumes, and it is shown that flame proofing does not diminish, even with lower densities if anything, it increases. In Examples 18 and 19, the fl~me resistance of 4 cm thick sheets io tested, which sheets were produced from an emulsion with - -55% water and unsaturated polyester cast resin, using a ~ ~ -silicate mixture (Example 18) and aluminium hydroxide (Example 19) and expanded glass (particle diameter 20-30 mm), The volume ratio of filler to emulsion? provided with flame-proofing agents, is 1 : 2. Example 19 has already been reported in more detail in the preceding description.
, i - 38 -~ .

10 5Z OS~D
In both Examples 18 and 1~, a temperature of 140C, at a distance of 4 cm from the maximum temperature on the other side, is not measured until after 55-58 minutes.
At the same time, this maximum temperature on the back, after a period of 55-58 minutes, is confined to the direct action of the burner on a circle of about 25 mm in diameter. In the surrounding area the temperature quickly falls to 60 - 70C, and reaches approx. 30C on the back at a distance of 6 cm from the burnt centre. The article is unaffected apart from the area of the direct effect of flames from the burner, The depth of the burnt out depression is 35 mm. In Example 19, the flame came through to the back after 60 minutes, whereas, in Example 18,~
the back remained completely undamaged.
For reducing inflammability per se, the same agents can be used in a higher concentration, while this can be restricted to particular parts or surfaces. In addltion to additional impregnation of the surface, inflammabiIity can be checked by a higher concentration of the flame~
retarding agents in the surface, or a subsequent coating.
At the same time, water-blnding drying agents can also be put to use, to advantage, e.g. by the addition of small quantities of hygroscopic salts such as calcium chloride, lithium chloride, glycerol, alcohols, glycols, 1~5ZOSO

carbohydrates, cellulo~es, and substances which become enriched with water, by means of the humidity in the air. The slight water concentration resulting therefrom has hardly any effect~
or no effect at all, on the insulating and drying properties of the material. The moisture content can be very accurately adjusted, and a maximum can be maintained even at a low average humidity of 25-30%.
According to the process according to the invention, shaped articles with a cellular structure, the pore w lumes .. . .
of which are 25-85% by volume and the pores of which are predominantly open, may be obtained. By means of appropriate shaping, all the structural engineering parts which are used -in building can be produced according to the proce`ss of the invention. Thus it is possible for example to manufacture~
according to the process of the invention, the shaped parts which are necessary for erecting walls, such as for example, wall slabs, tile-shaped members of all shapes and sizes~ wall-covering elements, supports, carriers, reinforcements, door and window frames, door panels and the likeO Similarly~
there may be produced, formworks for constructional purposes, individual formwork members, formwork stones and support members which are for example reinforced with glass fibre. Bases for oil and water tanks, and for bathtubs and similar apparatus~

~0 5Z~S~D

can also be produced according to the process of the invention.
Moreover it is possible to manufacture pipe lagging, insulation layers and whole insulation walls or insulated shaped parts according to the process of the invention.
However~ furniture, furniture parts, internal furnishings of homes, such as, for example, panel~, boards~
picture frames, and devices for hanging curtains, can be made according to the process of the invention. The process according to the invention also makes it possible to produce moulded parts which can be used, in all kinds of applications~
for fitting out large areas, as parts for industrial manufacture~
such as, for example, housing, temporary accommodation, and roof coverings. ~ `
Since the shaped articles of the invention, produced according to the process of the invention, prove practically non-combustible when flames are applied to them~ these shaped parts c~n also be used as so-called fireproof partitions or walls, and as fireproof doors.
The shaped articles according to the invention also have the considerable advantage that they are extensively resist~nt to weathering and are not subject to rotting.
By their relatively high pore volume and their low content of free water, the shaped article~ produced according to the invention are very light and show virtually no shrinkage, t compared with a porous shaped article the pores of which are completely full of water. The shaped articles according to the invention can rather be designated decidedly stable in form.
Even in the extreme conditions of an electric storm the shaped articles according to the invention keep their shape . over a fairly long periodO

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:; - 42 _

Claims (20)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for producing a shaped article with a cellular structure and a water content of not more than 14% by volume which comprises shaping and curing an emulsion comprising from 25 to 90 parts by weight of water dispersed in from 75 to 10 parts by weight of a liquid synthetic resin-monomer mixture comprising styrene or a methacrylic or acrylic acid ester and a copolymerisable unsaturated polyester or copolymer of styrene and butadiene and thereafter drying to provide a water content of not more than 14% by volume in the shaped article thus produced; the said emulsion contain-ing from 5 to 30% by weight of an inorganic flame-retarding component in powder form with an average particle size of not more than 50µ in diameter (the percentage being based on the total weight of emulsion), the emulsion having a dispersion level which is in the characteristic range prior to commencement of curing and the curing being effected at a rate whereby the emulsion gels before commencement of disintegration of the emulsion.

2. A process as claimed in claim 1 wherein one or more further ingredients selected from polymerisation catalysts, emulsifying agents, wetting agents, inhibitors, cross-linking compounds, softeners, fillers and dyes are incorporated into the emulsion prior to curing.

3, A process as claimed in claim 1 wherein the water content of the shaped article after drying is not more than 5% by volume.

4. A process as claimed in claim 1, 2 or 3 wherein the resin-monomer mixture comprises an unsaturated polyester dissolved in a mixture of styrene and methyl methacrylate in a weight ratio in the mixture of from 1:4 to 4:1.

5. A process as claimed in claim 1, 2 or 3 wherein the dispersion level of the emulsion is adjusted prior to commencement of curing by the incorporation of an emulsifying agent.

6. A process as claimed in claim 1, 2 or 3 wherein the dispersion level of the emulsion is adjusted prior to commencement of curing by the incorporation of an emulsifying agent in an amount of from 0.05 to 10%
by weight (based on the total weight of the emulsion).

7. A process as claimed in claim 1, 2 or 3 wherein the average particle size of the flame-retarding component is not more than 20µ.

8. A process as claimed in claim 1, 2 or 3 wherein the flame-retarding component comprises an inorganic compound which splits off water at elevated temperatures.

9. A process as claimed in claim 1, 2 or 3 wherein the flame-retarding component comprises an inorganic compound which splits off water at elevated temperatures, the inorganic compound comprising water glass, calcium sulphate dihytrate, magnesium or aluminium silicate, borax, aluminium hydroxide, asbestos or a crystalline salt containing water of crystallisation.

10. A process as claimed in claim 1, 2 or 3 wherein the flame-retarding component comprises an inorganic compound which splits off a flame-retarding gas at elevated temperatures.

11. A process as claimed in claim 1, 2 or 3 wherein the flame-retarding component comprises inorganic compound which splits off carbon dioxide at elevated temperatures.

12. A process as claimed in claim 1, 2 or 3 wherein the flame-retarding component is calcium carbonate or sodium bicarbonate.

13. A process as claimed in claim 1, 2 or 3 wherein at least part of the flame-retarding component consists of a substance serving also as a filler.

14. A process as claimed in claim 1, 2 or 3 wherein at least part of the flame-retarding component consists of a substance serving also as a filler which is perlite, chalk or asbestos.

15. A process as claimed in claim 1, 2 or 3 wherein the fire-retarding component is present in an amount of 5 to 20% by weight (based on the total weight of the emulsion).

16. A process as claimed in claim 1, 2 or 3 wherein the emulsion additionally contains a polymerisation catalyst in an amount of from 0.1 to 10% by weight (based on the weight of the emulsion).

17. A process as claimed in claim 1, 2 or 3 wherein the emulsion con-tains a filler component in addition to the flame-retarding component.

18. A process as claimed in claim 1, 2 or 3 wherein the emulsion con-tains a filler component in addition to the flame-retarding component and the filler component comprises fibrous or particulate material.

19. A process as claimed in claim 1, 2 or 3 wherein the emulsion contains a filler component in addition to the flame-retarding component and the filler component comprises a plastic, glass, clay, perlite, vermiculite, slag, pumice,quartz or asbestos having an average particle size of from 0.05 to 30mm.

20. A process as claimed in claim 1, 2 or 3 wherein the cured emulsion is subsequently dried at a temperature of from 15 to 50°C.