DE1569384A1 - Process for the production of porous moldings - Google Patents

Description

MR. · »DiPL-CHEM. WAITER Sill

aIF * SEPPEN ER

OR. JUR. DIPL-CHEM. H.-J. WOLFP DR. JUR. HANS CHR. AX

629 FItANKFURT AM MAIN = HOCHfT 30 JuH 196S

ADILONSIRASSi U

Our no. 10 526

doo. ttdieoo, SpA

Milan / Italy

Process for the production of porous shaped bodies

The invention relates to a "method for producing porous molded bodies with low density from synthetic thermoplastic substances based on styrene polymers and styrene copolymers, whereby at least one propellant consisting of chlorofluorocarbons is incorporated into the substance present in small particles suspended in water, and then the particles are incorporated by means of a heating medium is completely foamed and finally the completely foamed particles are heated in molds which are essentially completely filled with the particles and provided with holes through which the heating medium can flow, which is characterized in that the incorporation is carried out using a chlorofluorocarbon as' - ! - 'friction agent, which is a solvent for the polymeric substance and is gaseous at 15 ° C and -60 mm Hg pressure, at a temperature which is 5 to 40 ⁰ O above the soaking point of the polymeric substance, and that one to avoid one Agglomeration of the aqueous suspension during the addition of the propellant this in the presence of a mixture of an organic

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water-soluble suspending agent, an ion-active wetting agent and optionally one that is strongly dissociated in water Alkali or alkaline earth salt makes.

From the technology for the production of synthetic, thermoplastic, foamable en ilaterialien we know that as Propellant substances are used that develop gas within the polymer particles when this begins to occur Softening point are heated.

These propellants can be gases or organic and inorganic Be solids that decompose when heated, evolving gases; or can also be liquids be that have a low boiling point and for the polymer are not a solvent and are compatible with the latter. Well-known solid propellants are: Sodium bicarbonate, ammonium carbonate and bicarbonate, mixtures of urea and oxalic acid and various other compounds, which decompose when heated and develop gases such as nitrogen, carbon dioxide and ammonia.

The incorporation of the solid means can either be mechanical Mixing the agent with the synthetic, thermoplastic substance is done or by dissolving the Solids in the monomer and subsequent polymerization of the latter under conditions where the Propellant does not decompose.

This last operation requires that the process be carried out at relatively low temperatures that require long response times.

Gaseous inorganic substances suggested as propellants are: nitrogen, hydrogen, carbon dioxide etc. These agents are incorporated by introducing the gas into the molten polymer fairly high pressures,

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Such an approach requires expensive procedures and systems and also leads to poor quality products, especially in terms of preservability and invariance of the product. Indeed they lose synthetic, thermoplastic beads can be used as a friction agent gas used, which means that the volume increase in the subsequent foaming of the product is small «

Organic substances that are gaseous at room temperature and atmospheric pressure have also been proposed as propellants are such as methane, methyl chloride, methyl chloride mixed with propylene, propylene, propane, butane and analogous compounds. However, such a procedure leads to a ver Long storage times are unsuitable because of the extraordinary ease with which the gaseous Propellants, which are not a solvent for the synthetic, thermoplastic substance, from the soaked part * chen volatilize, which often reduces the content of the foamable Product of propellant under the to achieve foaming Good quality products will drop the required minimum values.

Many substances have been proposed as a volatile propellant. The most common are: petroleum ether fractions and aliphatic hydrocarbons with boiling points between 25 and 100 °, of which pentane, isopentane, hexane, cyclohexane alone or mixed with one another, as well as other compounds, oi “All these substances are not solvents or act loud ;, as a solvent, but are in every -PaIl with the used, synthetic, thenaoplastiochen substance compatible.

The Siiiführuii.r these liquid propellants, which are not solvents for the thermoplastic, synthetic substance, happens i ~ all ^ ernaiiiei. by Irish of the propellant un-

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indirectly with the monomer or with a solution of the polymer in the monomer, the polymerization is then carried out, taking care, however, that the Propellant does not volatilize, but on the contrary is absorbed by the polymer particles which are formed and incorporated into them will.

This procedure is extremely uneconomical, when it takes very long times for the polymerization and absorption of the blowing agent. In in some cases these periods can be up to three or four weeks and even more.

Another system for incorporating the liquid and non-conductive Propellant in the particles of the synthetic, thermoplastic substance consists in the introduction of the propellant ' by means of a suspension of a finely divided resin stabilized with suspending agents and at a temperature which is generally below the softening point of the synthetic thermoplastic substance to avoid agglomeration.

According to generally known methods, molded porous bodies of any size and shape are obtained from the foamable pearls obtained in this way, which contain homogeneously dispersed blowing agent, in that the thermoplastic, synthetic substance is formed as non-foamed or only partially foamed pearls by means of hot water or steam be heated in closed pores provided with holes. By heating the thermoplastic resin to temperatures close to the softening point, one achieves the return of the not or partially foamed particles and the simultaneous inside of the particles to become porous with low apparent density. ι ■ '■

The task of the experience is therefore one before the one above specified table parts and difficulties free procedure for

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Manufacture of synthetic, foamable, thermoplastic substances, that is, substances which are able to take on cell structure when heated with a considerable increase in volume, and for the manufacture of porous bodies with a low density as well. ^ ^S are also verachäumbare beads are obtained with particularly good stability and preservability of synthetic thermoplastic materials, wherein the beads for foaming and sintering and subsequent forms are suitable porous body and wherein the verschäumba _ren beads containing at least a gaseous blowing agent comprising a solvent for the synthetic, thermoplastic substance. The porous bodies should also have special physical and mechanical properties and completely foamed particles should be produced which are essentially free of gaseous propellants.

These and other goals, which are derived from the following, in-depth Description emerge, according to the invention Method achieved, i.e. that with the aqueous Suspension of the granules of synthetic thermoplastic substance obtained by grinding or the suspension of the Pearls as received in the last polymerisation phase is immediately exposed to the swelling effect of at least one propellant which is gaseous at 15 ° and 760 mm Hg and for the synthetic thermoplastic substance used represents a solvent, this propellant consisting of fluorochlorinated hydrocarbons, which as such or used in combinations with one another.

The foamable particles thus obtained are first through prolonged heating foams, then they will be after a reasonable Tempering introduced in the form of a known type, in which the au porous plastic bodies are sintered, which have valuable properties to have.

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BATH

The synthetic, thermoplastic substances that can be used in the process according to the invention are polystyrenes and copolymers of otyrene and alpha-ethylstyrene, styrene and other monomers, such as, for example, acrylates and methacrylates, Ki-chpolymerisate with a chewable rubber character Styrene-butadiene type, etc. In general, polymers of styrene and styrene-polymerizable vinyl moiiomers are advantageously used, these products containing at least 50 percent by weight of polymerized styrene. . ynerisate, 'are used in each ^{i | l} all, it is preferred, polystyrene or Irodukte to use that in the .'iiiichpoly: included obtained ^ erisaticn of styrene with other l'ionomer and a high Prosentsatz to polymeriniertem styrene.

The '!' Friction means eraässen than the erfindungo ₀ ^ learn substances used are chlorine-fluorine substituted derivatives of aliphatic hydrocarbons containing a low number of carbon atoms, which are used alone or in combination. The compounds recognized as useful or 'Je: ci; .che are solvents for the synthetic substances and also have a boiling point of up to 15 at atmospheric pressure and are therefore gaseous.

All chlorofluorine derivatives of ... ethane and ethane alone or as Mixture can be used in amounts of 2 to 40 wt .- ^, based on the synthetic thermoplastic agents used can be used to advantage. In every ^ 'all it is preferred to use the derivatives in different denominations with reference to the synthetic thermoplastic substance in an amount of up to 25 Gev /. ~ $ to be used alone or in combinations, '

The propellant is injected into the aqueous suspension of the synthetic thermoplastic substance, "the 50 minutes stirred for up to three hours and stabilized by means of a stabilizing agent, which is made of an organic water

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soluble suspending agents, such as partially or fully hydrolyzed polyvinyl acetate and an ionic wetting agent, advantageously based on an organic sulfonate and possibly strongly dissociated salts of alkali and alkaline earth metals consists.

The introduction of the propellant takes place at a 5 to 40 over the softening point of the synthetic thermoplastic substance lying temperature instead.

The foaming of the ^w on these particles else obtained is performed in 2 stages, the first stage consists of a TotalverKchäumung of the particles by heating with a hot fluid in appropriate devices wherein the procedure is such that the particles of the largest eri'ahrensbedingungen, under the / possible degree of expansion. The second stage consists of sintering the foamed particles by heating them into molds of a known type and according to methods known in the art for the production of ma ..iive or porous bodies. Such forms v; earth In the v »esen 1 borrowed up to their entire volume with already foamed particles. The forms are stranded with openings for penetration of the irritant and can have continuous or perforated walls.

Ii .'- ch eiaer preferred but not au schliesblichen Ausführu: i. _T; ^ i "orn the erxindungogemässen process styrene is polymerized in an aqueous suspension in the last S'tui'e the roiyinerisaticm when the ^x e ..! temperature at liart et \ ^ a 100 °, Werder. ~ 1 parts based on parts of polystyrene 1ÜÜ a vJeini. NHEs from 30 wt ^£, o ^ richlorfluorrnethan 'and 1υ weight) ³ Z'ifluordichlorniethan (a 2.it :; i the boiling point of the mixture of 9 ^) u :: niittelb'3 _r in the olyrerisntionsautoklav. The suspension is kept at about 110 °, with constant stirring for 60 minutes, then the suspension is cooled and the foamable pearls, ir. the e-foaming agent .jlsichfünr-ig is incorporated

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enteric sgeführt EAI from the autoclave, dried and placed in the bearing zone, or they are directly processed to foamed en porous bodies. The foamable particles obtained on this are foamed by heating to about 90 ° in a hot air oven, with throwing under these conditions for one hour. ^^ ^e particles experience a considerable increase in volume, combined with a substantial volatilization of the propellant.

However, the foamable particles may conveniently can also be heated by placing them in a hot water bath Be immersed or a -heiseen V / water steam stream or partially or exposed to completely burned gases.

The foamed completely after a tempering time of about 24 hours Particles are shaped in such a way that they essentially fill these shapes up to their entire volume, then they are known to nr-.ch procedures, such as those for example used in the production of foamed rubbers, foamed.

The foamed particles ^ are in the openings with the inlet of the irritant-provided molds exposed to hot air from 110 to 120 °. On this way there is another, insignificant one Foaming of the particles takes place, but this is limited to the filling of the free spaces by the particles, at the same time sintering takes place to form porous bodies which have the shape and dimensions of the used i'orin have.

In this way, shaped bodies are obtained which have an apparent density of about 18-20 kg / cm and are valuable Have properties.

In a modification of the method of understanding, the aqueous suspension of rclystyrene can a _13o h ^ du ^ oh o ^ plten that π one

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finely ground .folystyrene in water in the presence of a suitable Suspension-lit means suspended.

This is a particular advantage when using hydrochlorofluorocarbons as a propellant in deia according to the invention ^ experienced is that these mixtures are generally solvents for the polystyrene, for those mentioned above Copolymers and for the other thermoplastics listed above Substances are. The polymer particles are therefore extremely easily saturated with the blowing agent.

Another advantage of the inventive method, the also on the use of chlorofluorocarbon mixtures with a low number of carbon atoms as a blowing agent, consists in that the foamed particles thus obtained because of their solubility in the mixtures mentioned have better preservation and stability properties than such Particles made using other ^ gaseous or flux I-jjsr Propellants that are not solvents or only swelling agents for the synthetic, thermoplastic substances, or under Preference is given to the solid propellants mentioned above became e η.

Another advantage achieved in either the foaming or sintering stage of the process of the present invention is that because of the flammability of the Chlorofluorocarbons used as propellants are hot Air can be used as a heating medium, thereby avoiding difficult process steps without the risk of explosion or fire can be, as s.B, those with steam generation, such as they are used in conventional procedures.

Sin is obtained another advantage, foaming also in either the locking or sintering of the particles to the porous rmkörpern Po according to the present invention is that the use of special ventilating

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plants or air fil fcorvotriohtunken many of the Ungif tijizei t and. ichtbrennbariceit as "blowing agent verv; avoid ending chlorine fluorocarbons lcarui, dr, normal -Lüftungsanlagen, the trees in cien exist, sufficient to ensure the safety of - ^ edienungspersonals to _f -; ewährlejsten.

The following examples serve to further explain the Invention.

example 1

An aqueous suspension of olystyrene beads, as is obtained, for example, in the last phase of an aqueous) Stvrolsusr.er.sionspolymeric-itioii, was by means of eii.es ,, eei ^ et. η stabilized suspending agent, which consists of the following substances in 'j.ei. specified i ^ ri; _: Ien be .tend: 0.05 G-ew, - ^L 3ile of 86 '/ o hydrolyzed polyvinyl acetate, 0.12 -üvi .-'i'eile a. Condensation exjrodur: tes from i-omaldehyde and -atriutrnaphthalinsulfonat and 0.1 (lev /.- • '• part of LaCl, based on 100' parts of the iol ^ / styrene, and with further heating in the same polymerization autoclave with 20 ! 'rush Tetrachlordi fluoroethane, based on 100'! 'rush polystyrene, treated, the introduction of the blowing agent in the aqueous satsuspension r, which was about one hour sta _r v, found at about. 110 ° under jJruck place,

The suspension was cooled, purified, centrifuged and dried at room temperature.

"- - had a eilchen ^f ieh-.lt to i'reibmittel of 13 u-ew .->, Luch iionaten a storage time of two had 'the' ehalt of the propellant 20 Jo reduced" The thus obtained foamable Vieise

After five months the propellant level was down, although it was down

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had significantly reduced, no el. sufficient to «Foamed ■ t'ro.iukt of very good quality. 0.30 kg of the above displaceable l-olystyrene particles with a ^ eh old εη ^ friction agent of 13 üev /.-'/ j were about Held in a hot air oven for 90 to 95 ° for 60 minutes.

The -i-eilehen thus obtained were completely foamed, ie the foaming was as much as possible under the procedural conditions _c ; un..en.

The in this "else ver; chäumten 'l'eilchen were annealed 24 hours Then, they were placed in a rectangular flat Porri Wänien that nit üffi:.. Un _t; en zui.i inlet of iieisl.ittels was provided.

Heisse Lui't from 115 to 118 was completed for 30 minutes blown with the little violet filled shape, and after that Cooling was a porous, rectangular plate with a dense before. 20 kg / m received.

■ Example 2

3] ine »iusr; ensioii : iv, 3 1OC xeileii vain kernigen ■ uet ': acrylate-i'ii.5c.: _ I slyrierisats in 10l parts V / water was in an autoclave go.eban, -. To 105 under - -you ei-jitst and nit τ eis of a _t -eoi riveting suspension medium stabilized, that from foigeiidei. üubstansen in the given ^ narrow constants: Q, 1 uev. '. - hurry up. :: u 86 * '* hydrolyzed polyvinyl acetate, 0.4'je-; · .'.-- i-cile one,. -κ ■ e / is-'ticnsprr'n.ui. "it from. cr-ialdehyde and ^A > 2 * riuniiaphthalinsulfv / i.at u: id L, 2 'each - part CaOl ₂ , related to' 10C icilc des I.ischpolyr.ori crvts, 2C ^ 'hurry of a üerni ches from Jj *; j iiri, -: ii: r_'luuraetnan m: i ^ .-' iJicx-loridflucrniexijan ■ oie; i? -;. \ : i 1 ''"/'-r ν \ ^ \ at about ' -κ. ¹ ; ⁰ eii .. eT-hert. Das: t'ij; ren ... ,, -, p -, _iG j_ 3-tMi: -? Rr. f-'i'tgese · '. ~ t, the, / oaante l "-. asse was gutm gel:; '. ilt, -v / A \ lz v: - \: \ Treic :: ittel .i. ^.? c ^; tväniiter. -" - .eilc'ien wur en v - ?: i lur ^ u. ^: ; p3 ::. 73 : i,. ; ⁺ re: ut ;. Jiese 'Jei2 c'.i- ^ r. vu · "-cn, ii; ·. 2 '.. ae: n s.1-3: o ¹ ^ e. ::?: ■ ren, diiroh iirhlrno; -. r: i- .-. c-isscr ajU2 "t in " iiisu:

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c
Oiling at yo to 95 60 minutes before 'johüuiat "The on this' ^ ei. '.' S received-.]! The foamed particles were placed in an I ¹ orm after tempering, dj.e that corresponded to the above - ^ ice-p'ielß, in a narrow, d ^: .; _BB ß-, · _e ¹ ^ orm was completely filled,

With hot air of about 115 to 118 ° it was about 10 minutes heated for a long time, thereby sintering the particles.

I-Jach the; Cooling down vmr a porous body with a density of 'Yj kg / m obtained. It looked compact and homogeneous and did not crumble inside. It was resistant to ih.'uck uiid iiruch and very suitable as a heat-insulating and acoustic material, so that it is used for most of the different purposes for which such a material is used could be.

£ v> vmriäe proceed according to your ^ experience ^ of example 1, where aln synt; et · ', before thernoplastiache nouns. _ni , _e ^ _n graft mixed polymeris ^ t of tyrol on a .butadiene-styrene rubber in Γόγπ small pearls and for stabilization a suspension of the following -us: .i: ri] nenset;: were not used: 0.15 Ciev.- - "- rush of about 86 '' · - hyarolyeiertein polyvinyl acetate, 0.6 wt ^X rush eii.es Koniensations} roduktes of formaldehyde and I: atriumnaphthalinsulfonat and 0.2 Gev; maybe parts NAOL, as ireibmittel wur.ten 25 Parts of a ^ enincns of difluorodichl '. Λ

Hi.:chpoly neren ver

Jie. The obtained v & r "C: flattened particles have a content of I-propellant. 8 ^ ev> .- ^>. -. After the / experience of Example 1, porous I ^ ür ^ or with a density of 25 kg / m 2 were obtained.

Example 4

Sir: e aqueous sus _:. Enßion ve η dtyrene-α— ■. ^ Trtylstyrene-Hischpolymit air ^ e-.alt of 75 '".? ..-. Pci; / :, trized 009810/15 8 B

^Ö * D original

Styrene was was as -it in the last Polymerisationaphase obtained, stabilized by means of a suitable Suspensionsmitfcels, which consisted of the following substances in the indicated ilengen: ü, 005 of ropes to 86 ^c ß> hydroIysiertem polyvinyl acetate, 0.1 parts of a condensation product from "ormaldeiiyd and liatriumnaphthalinsulfonat and 0.1 part of IJaCl, each based on 100 parts of water and 100 parts of the I-II jchpolymetisats".

This suspension was benedeit in the same polymerization autoclave at 105 ° with stirring with 20 parts of a mixture of 60 ^σ β> difluorodichloromethane and 40 ^{° C} trichlorofluoromethane (boiling point -20 °).

The introduction of the emi rope into the stirred aqueous polymer suspension took place under pressure at about 100 for 90 minutes.

The whole mass was then cooled, centrifuged and the soaked Part cn en were dried at room temperature, after which they had a propellant content of 9.5 G-ew.-vo.

The post-polymer particles obtained in this way were placed in a large metallic cylinder, the bottoms of which consisted of wire mesh of a suitable size, so that the foamable particles did not fall through. Üin hot air stream of 110 was through a bottom of the cylinder 15 minutes long introduced.

The copolymer particles foamed in this way, the were essentially free of propellant were placed in an i'orm which corresponded to that of Example 1.

This form v / urde fa, ut completely filled and by means of hot Air heated for about 15 minutes.

In this way a porous body with a density of

BATH

Example 5

An aqueous suspension of i'ol ^ byrene beads, as obtained in the last phase of an aqueous styrene suspension polymerization, was stabilized by means of a suitable suspension medium which consisted of the following substances in the specified amounts: 0.2% by weight -J-'eile one to 86 ^c / o hydrolyzed polyvinyl acetate ^ and 0.6 wt .- 'J-'eile a condensation pro; ^; ucts of formaldehyde and sodium naphthalenesulfonate, based on 100 parts by weight of the polystyrene.

The stabilized suspension was given, with stirring, 20 l parts, based on the weight of the polystyrene, of a mixture of 30 wt .-; ii ¹ ri chlorofluorine than and 20 ~ r & w .-? I dichlorodirluoromethane to ^ .e:; just. The introduction of the propellant took place while doing something. 1 stumble at a temperature of 110 C.

The suspension was cooled, purified, centrifuged and at üaumt erape ratur dry t.

^{The verrjonäuri.baren x} e loans obtained in this way had . _s a propellant content of 15; j. j

After two months of storage, the free average ^ e ^ old ί had decreased by 18> o. After five months the propellant content, although significantly reduced, was still sufficient to produce ocnaumstoff of good quality.

0.50 kg on representational "else obtained foamable -tolysty _r olperlen with a blowing agent content of 15 '* 60 minutes, held for eissluftfofen at 95 C in an ^Al - ^ s were completely foamed particles Erhe ^ th ^.. - cii one;: Tempering time of 24 hours, these particles were converted into a ■

given cylindrical shape with flat walls covered with holes was provided through which the pre-foamed for sintering particles required pickling agent flowed in.

Was 35 minutes long eir.geblasen air with a '.Temperature of 110 ⁰ C in the completely filled with foamed particles i'orm and, after cooling to obtain a porous plate having a zylindris he -density of 18 kg / m.

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Claims (1)

"■ _ ! R 69384 P A ΐ E Κ ϊ A K.S? K b C Ii .5 ί 1. Process for the creation of porous polymer bodies with low density from synthetic thermoplastic substances on the basis of styrene polymers and - _n jο <-.} -, ρ ο interiors, where naa. that in small ones suspended in water; At least one propellant from chlorofluorocarbonsBG 'substance is incorporated into the present substance, so that the particles are completely venched and foamed by means of a heating medium. Finally, the vcllständi _£; veruchau-.iten Teilciien in -oriüen erliitst- which are fully filled with the .particles in the v; e;:; publicly and provided with holes through which the ^ r.iziai ttel ei; .strom came :, thereby .rekenn- 'denotes that z-.azt the Üinarbeitunj under v'erv.'ei.ciiu: _{w of} a Chlori'liaorkohleirw'-isaerstoffes as!' friction agent, which a Lüsunjeinit -: - el for the polymeric .Stoff and is at 15 C and 7CiO mm Hj-J) ruck gasförzaig, ur at a tfer.peru +, the rang from 5 to 40 O Einwei about your egg spunk t of the polymeric fabric lie,: - ^1:, carried out, urd that in order to avoid an accumulation of the aqueous suspension during the addition of the rubbing agent, this in the form of an organic, water-soluble suspending agent, an active substance. etziriittel and possibly a s-ta'ric ili'iV / aßsc-r lissoziicrten Alknli- or-Erdalk & lisals Claim 1, 3? I .-: urch germinated ^ eiciinet that one '.ieiiä from a ·. partly; ice or fully Viy.iroiycie .'- '+ ei. - ". ¹ IyV invitee tat, a cr ^ anis -hen sulphonate u: ii ^ egebe:>^;; case £: eir.em strongly ir" ater iissociated alkali- oi-3r Sr ali-.alisals, verweiijet. 009810/1585 _Ο1ΛΙΜΔ , BATH ORIGINAL 3. The method according to claim 1, characterized in that one as an aqueous suspension of the particles of synthetic thermoplastic substance immediately those in the last Phase of an aqueous emulsion polymerization obtained suspension used. 4, method according to claim 1, characterized in that _S8 one as an aqueous suspension of synthetic thermoplastic particles used a suspension obtained by grinding the synthetic thermoplastic substance and suspending the obtained particles in Viasser. [; # Method according to claims 1 - 3> characterized in that copolymers of styrene are used in which a high "percentage, but at least $ 50 polymerized Styrene are included. 6. The method according to claims 1-4, characterized in that that the propellant used is chlorofluorine derivatives of lower aliphatic hydrocarbons, preferably of methane or ethane, in an amount of 2-40% by weight, preferably 5-25% by weight, based on the synthetic thermoplastic Substance, used. 7. The method according to claims 1-5> d · characterized in that during the entire foaming process and during the production of the chaffed bodies as pickling air, Steam and partially or fully combusted gases are used. For · * »<? <? · ItfiWa S.p.A. Mailc.nd / Italy Lawyer 009810/1585