CH463786A - Process for the production of polyurethane foam parts with a compact outer skin - Google Patents

Process for the production of polyurethane foam parts with a compact outer skin

Info

Publication number
CH463786A
CH463786A CH1498165A CH1498165A CH463786A CH 463786 A CH463786 A CH 463786A CH 1498165 A CH1498165 A CH 1498165A CH 1498165 A CH1498165 A CH 1498165A CH 463786 A CH463786 A CH 463786A
Authority
CH
Switzerland
Prior art keywords
foam
production
mold
outer skin
polyurethane foam
Prior art date
Application number
CH1498165A
Other languages
German (de)
Inventor
Hans-Dietrich Dr Krug
Original Assignee
Freudenberg Carl Fa
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Freudenberg Carl Fa filed Critical Freudenberg Carl Fa
Priority to CH1498165A priority Critical patent/CH463786A/en
Publication of CH463786A publication Critical patent/CH463786A/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/34—Chemical features in the manufacture of articles consisting of a foamed macromolecular core and a macromolecular surface layer having a higher density than the core
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
    • B29C33/40—Plastics, e.g. foam or rubber
    • B29C33/405—Elastomers, e.g. rubber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
    • B29C33/60—Releasing, lubricating or separating agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
    • B29C33/60—Releasing, lubricating or separating agents
    • B29C33/62—Releasing, lubricating or separating agents based on polymers or oligomers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
    • B29C44/04—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles consisting of at least two parts of chemically or physically different materials, e.g. having different densities
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/16—Catalysts
    • C08G18/22—Catalysts containing metal compounds
    • C08G18/24—Catalysts containing metal compounds of tin
    • C08G18/244—Catalysts containing metal compounds of tin tin salts of carboxylic acids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
    • B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2075/00—Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2083/00—Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/04—Condition, form or state of moulded material or of the material to be shaped cellular or porous
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/04—Condition, form or state of moulded material or of the material to be shaped cellular or porous
    • B29K2105/043—Skinned foam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/24—Condition, form or state of moulded material or of the material to be shaped crosslinked or vulcanised
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2883/00—Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as mould material
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2375/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2375/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
    • C08J2375/04—Polyurethanes

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)

Description

  

  Verfahren     zur    Herstellung von     Polyurethanschaumstoffteilen    mit kompakter Aussenhaut    Die Erfindung betrifft eine -neue Verwendung von  organischen     Zinnverbindungen    bei der     Herstellung    von       Schaumstoffkörpern.     



  Es ist bereits bekannt,     Schaumstoffe    mit massiven  Deckschichten zu überziehen. Im einfachsten Fall klebt  man auf einen Schaumstoff eine PVC- oder Gummifolie  auf. Da dieses handwerkliche Verfahren     jedoch    äusserst  umständlich, zeitraubend und damit teuer     ist,    wurde  auch schon früher versucht, andere,     schnellere    Her  stellungsverfahren zu entwickeln.  



  Ein entsprechendes Verfahren wird z. B. in der  DAS Nr.<B>1127</B> 068 beschrieben. Man stellt dabei zu  erst die Aussenhaut her, die     nachträglich    mit einer       schäumbaren    Paste teilweise ausgefüllt wird. Beim Auf  schäumen wird dann die Hülle voll mit Schaumstoff  ausgefüllt.  



  Bei     sämtlichen        bekannten    Verfahren benötigt man  also zwei Körper,     einmal    die     Aussenhaut,    zum     anderen          den    Schaumstoff. Beide müssen anschliessend irgend  wie vereinigt werden. Bisher war es nicht möglich, z. B.  während des Auf- und     Ausschäumens    der Paste gleich  die massive Deckschicht mit zu erzeugen.

   Wenn man  
EMI0001.0019     
  
    z. <SEP> B. <SEP> eine <SEP> übliche <SEP> Desmophen/Desmodur*-Paste, <SEP> wel-     
EMI0001.0020     
  
    * <SEP> Warenzeichen <SEP> der <SEP> Farbenfabriken <SEP> Bayer, <SEP> Leverkusen            che    bekanntlich zur Herstellung     eines        Polyurethan-          schaumes    benötigt wird, in eine übliche Metallform  einfüllt     und    diese verschliesst, so     beginnt        zwar    die Paste  aufzuschäumen     und    füllt auch die Form aus.

       Dabei    ist  es wahrscheinlich, dass -     wenigstens    unter     bestimmten          Bedingungen    - sich auch     eine        Deckschicht    bildet, de  ren spezifisches Gewicht höher ist als das des Barunter  liegenden Schaumstoffes. Mit anderen     Worten:        Beim     Aufschäumen von     geeigneten    Pasten     bildet    sich auto  matisch     eine    Deckschicht.

   Allerdings ist es nicht mög  lich, auf diese     einfache    Weise mit Deckschichten ver  sehene     Schaumstoffkörper        herzustellen.    Die     Deckschicht     haftet nämlich nicht nur äusserst fest auf dem     darunter          befindlichen    Schaumstoff, sondern auch an der Wan  dung der Metallform.    Versucht man nun gewaltsam den Körper aus der       geöffneten    Form zu ziehen, so reisst die Deckschicht viel  fach ein. Teile davon bleiben     auch    an der Metallwand  kleben.  



  Aus diesem Grund wurden eben     Schaumstoffkörper     mit massiven Deckschichten ausschliesslich nach den       eingangs    geschilderten Verfahren     hergestellt.     



       überraschenderweise    wurde nun gefunden, dass man  doch in einem einzigen Arbeitsgang sowohl das Auf  schäumen als auch die Bildung der massiven Deck  schicht, die zum Schutz des     darunterliegenden        weichen          Schaumes    dient, bewirken kann.  



  Das entsprechende Verfahren zur     Herstellung    von       Polyurethanschaumstoffteilen    mit kompakter Aussenhaut  durch Einfüllen von     wasserhaltiger        Diisocyanat-Diol-          Paste        in.    eine Form ist dadurch     gekennzeichnet,    dass  man die Wandung der Form mit einer organischen     Zinn-          verbindung        anreichert,    und dass die genannte     Paste    einen  Wassergehalt von 0,1 bis 1     GewA    aufweist.

   Wesentlich  ist also, dass man die Wand der Form mit einer dünnen  Schicht einer     organischen        Zinnverbindung        einreibt.    Als  organische     Zinnverbindungen,    werden genannt:       Zinn-II-Äthylhexylat,          Zinn-II-Isooctat,          Zinn-II-Ricinoleat,          Zinn-II        Naphthenat,          Zinn-IV-Äthylhexylat,          Zinn-IV-Isooctat,          Zinn-IV-Ricinoleat,          Zinn-IV-Naphthenat,          Di-n-Butylzinndilaurat.     



  Sie     kommen    vorzugsweise in Benzin gelöst zur An  wendung.  



  Sehr     günstig    ist die Verwendung einer Form aus       Silikongummi.    Es hat sich nämlich gezeigt, dass die or  ganische     Zinnseife    beim Auftragen auf die Wand der  Form in dieselbe     eindiffundieren    kann.

   Füllt man nun  eine derart     präparierte        Silikonform    mit den Ausgangs  komponenten für den     Polyurethanschaum,    so     bewirken     die an der     Oberfläche    der Wand     vorhandenem.        geringen         Mengen der organischen Zinnseife die     Ausbildung    einer  relativ dünnen Haut auf dem     Schaumgummiteil.    Wenn  man dasselbe aus der Form     nimmt,    dann ist zunächst       anzunehmen,

      dass die     Oberfläche    der Wand nunmehr  von     Zinnseife        frei    ,ist. In diesem Fall diffundieren aber       verhältnismässig    schnell     wiederum        geringe    Mengen der  in der Wand vorhandenen     Zinnseife    auf die Oberfläche  der Wandung     und    gewährleisten so erneut die Bildung       eines        Polyurethanschaumstoffteiles        mit    kompakter     Ober-          flächenhaut.     



  Nach der     Herstellung    von     etwa    50     bis    100     Poly-          urethanschaumstoffteilen    sind jedoch die Oberfläche und  die     Oberflächen        nahen    Schichten der     Silikonform    von  Zinnseife befreit. Es kommt dann nicht mehr zur Aus  bildung der     gewünschten    kompakten Oberflächenhaut.

    Man braucht jedoch nur die     Oberfläche    mit     einem.        mit     Zinnseife     getränkten    Wattebausch kurz     einzureiben.    Es  dringt dann genug     Zinnseife    in die     Silikonwand    ein,  um erneut die Herstellung von 50 bis 100 Schaum  stofteilen mit     kompakter    Haut zu     gewährleisten.     



  Wie schon oben erwähnt, ist     derselbe        Effekt    auch  bei der     Verwendung    einer mit Zinnseife     eingestrichenen          Metallform        zunächst        festzustellen.    Da jedoch in die  Wandung einer     Metallform        die    organische     Zinnseife          nicht        eindiffundiert,

          werden    die auf der Oberfläche sich  befindlichen Mengen der     Zinnseife        schon    bei der     ersten          Bildung    eines     Polyumthanschaumstoffteiles    verbraucht.

    Man müsste     hier        also    vor der Herstellung     eines    jeden       Schaunvstoffteiles    die Metallform jedesmal     mit    Zinn  seife einstreichen, was     selbstverständlich    sehr     umständ-          lich        ist.    Aus diesem Grund bevorzugt     man    Wandungen,  welche eine gewisse     Porosität    aufweisen,

   um ein Ein  diffundieren der     Zinnseife    zu     gewährleisten.        Ausser    den  bereits genannten     Silikonformen        kommen    auch Formen  aus Polyester usw.     infrage.    Es hat sieh ferner     gezeigt,     dass besonders     günstige        Ergebnisse    erzielt werden kön  nen,     wenn    die     Desmophen/Desmodur-Ausgangspaste     nur verhältnismässig wenig Wasser     enthält.        Es    sollen  0,1 bis 1     GewA    sein.

   Bei     Verwendung    von mehr Was  ser wird der Schaum zu sehr auftreiben, was wiederum  die Bildung einer kompakten Aussenhaut beeinträchti  gen würde.    Endlich ist zu beachten, dass heute auf dem Markt  sehr viele     Desmophen-    und     Desmodur-Typen    erhältlich  sind. Zur     Durchführung    der Erfindung wird man die  jenigen Ausgangskomponenten bevorzugen, die die     Her-          stellung    eines Schaumes mit hoher     Kerbzähigkeit        ge-          währleisten.    Es sind dies z. B.     Desmophen    3900 und       Desmodur    1234.  



  Die Herstellung einer kompakten Aussenhaut nach       denn.        Einstreichen    der Formwandung mit     einer    organi  schen Zinnseife kann man sich wie folgt     erklären:     Nach dem     Eingiessen    von     Desmophen        und        Desmodur     setzt eine chemische Reaktion unter Bildung von langen  Molekülketten ein.

       Diese    Moleküle gelangen bereits mit       der    Wand in dem Augenblick     in    Kontakt, in dem     eine          endgültige        Aushärtung    des Schaumes noch nicht     erfolgte.     Die noch     aktiven    Stellen des Moleküls, hier aktive       Nebenvalenzen    genannt, lagern sich fest an die Metall  wand an. Enthält die Metallwand jedoch eine organische  Zinnseife, dann wird eine chemische Reaktion     zwischen     zwei     aktiven        Nebenvalenzen    des     Polyurethanmoleküls     katalysiert.

   Es sind dann keine     Valenzen    mehr frei,  welche sich an die Wand     anlegen    könnten.



  Method for producing polyurethane foam parts with a compact outer skin The invention relates to a new use of organic tin compounds in the production of foam bodies.



  It is already known to cover foams with solid outer layers. In the simplest case, a PVC or rubber sheet is glued to a foam. However, since this manual process is extremely cumbersome, time-consuming and therefore expensive, attempts have been made earlier to develop other, faster manufacturing processes.



  A corresponding method is z. B. described in DAS No. <B> 1127 </B> 068. First, the outer skin is produced, which is subsequently partially filled with a foamable paste. When foaming, the shell is then completely filled with foam.



  In all known methods, two bodies are therefore required, one the outer skin and the other the foam. Both must then be united somehow. So far it has not been possible to B. to produce the same solid top layer during the expansion and foaming of the paste.

   If
EMI0001.0019
  
    z. <SEP> B. <SEP> a <SEP> common <SEP> Desmophen / Desmodur * paste, <SEP> wel-
EMI0001.0020
  
    * <SEP> trademark <SEP> of <SEP> Farbenfabriken <SEP> Bayer, <SEP> Leverkusen which is known to be required for the production of a polyurethane foam, is filled into a conventional metal mold and this closes, the paste begins to foam and fill also the shape.

       It is likely that - at least under certain conditions - a top layer is also formed, the specific weight of which is higher than that of the foam underlying the bar. In other words: when suitable pastes are foamed, a top layer automatically forms.

   However, it is not possible, please include to produce foam bodies provided with cover layers in this simple manner. The top layer not only adheres extremely firmly to the foam underneath, but also to the wall of the metal mold. If you try to forcibly pull the body out of the open form, the top layer will tear in many ways. Parts of it also stick to the metal wall.



  For this reason, foam bodies with solid outer layers were produced exclusively according to the processes outlined above.



       Surprisingly, it has now been found that both the foaming and the formation of the solid cover layer, which serves to protect the soft foam underneath, can be brought about in a single operation.



  The corresponding process for the production of polyurethane foam parts with a compact outer skin by filling water-containing diisocyanate-diol paste into a mold is characterized in that the wall of the mold is enriched with an organic tin compound, and that said paste has a water content of 0 , 1 to 1 GewA.

   It is therefore essential that the wall of the mold is rubbed with a thin layer of an organic tin compound. The following organic tin compounds are mentioned: tin (II) ethylhexylate, tin (II) isooctate, tin (II) ricinoleate, tin (II) naphthenate, tin (IV) ethylhexylate, tin (IV) isooctate, tin (IV) ricinoleate, tin IV naphthenate, di-n-butyltin dilaurate.



  They are preferably used dissolved in gasoline.



  The use of a silicone rubber mold is very beneficial. It has been shown that the organic tin soap can diffuse into the mold when it is applied to the wall.

   If you now fill a silicone mold prepared in this way with the starting components for the polyurethane foam, the effects present on the surface of the wall. small amounts of the organic tin soap cause a relatively thin skin to form on the foam rubber part. If one takes the same thing out of the mold, then one must first assume

      that the surface of the wall is now free of tin soap. In this case, however, small amounts of the tin soap present in the wall again diffuse relatively quickly onto the surface of the wall and thus again ensure the formation of a polyurethane foam part with a compact surface skin.



  However, after about 50 to 100 polyurethane foam parts have been produced, the surface and the layers of the silicone mold close to the surface are freed from tin soap. The desired compact surface skin is then no longer formed.

    However, you only need the surface with one. Briefly rub cotton ball soaked with tin soap. Enough tin soap then penetrates the silicone wall to ensure the production of 50 to 100 foam parts with compact skin again.



  As already mentioned above, the same effect can be seen when using a metal mold coated with tin soap. However, since the organic tin soap does not diffuse into the wall of a metal mold,

          the amounts of tin soap on the surface are already used up when a polyumthane foam part is first formed.

    So you would have to coat the metal mold with tin soap every time before you manufacture each piece of fiberglass, which is of course very cumbersome. For this reason, preference is given to walls that have a certain porosity,

   to ensure a diffusion of the tin soap. In addition to the silicone molds already mentioned, molds made of polyester etc. can also be used. It has also shown that particularly favorable results can be achieved if the Desmophen / Desmodur starting paste contains only relatively little water. It should be 0.1 to 1 GewA.

   If more water is used, the foam will expand too much, which in turn would impair the formation of a compact outer skin. Finally, it should be noted that there are many Desmophen and Desmodur types available on the market today. To carry out the invention, preference will be given to those starting components which ensure the production of a foam with high notch toughness. There are z. B. Desmophen 3900 and Desmodur 1234.



  The production of a compact outer skin according to then. Applying organic tin soap to the wall of the mold can be explained as follows: After Desmophen and Desmodur have been poured in, a chemical reaction starts with the formation of long molecular chains.

       These molecules come into contact with the wall at the moment when the foam has not yet fully cured. The still active parts of the molecule, here called active secondary valences, are firmly attached to the metal wall. However, if the metal wall contains an organic tin soap, then a chemical reaction between two active secondary valences of the polyurethane molecule is catalyzed.

   There are then no more valences free that could be placed against the wall.

Claims (1)

PATENTANSPRUCH Verfahren zur Herstellung von Polyurethanschaum- stoffteilen mit kompakter Aussenhaut durch Einfüllen von wasserhaltiger Diisocyanat-Diol-Paste in eine Form, dadurch gekennzeichnet, dass man die Wandung der Form mit einer organischen Zinnverbindung anreichert, und dass die genannte Paste einen Wassergehalt von 0,1 bis 1 GewA aufweist. PATENT CLAIM A process for the production of polyurethane foam parts with a compact outer skin by filling water-containing diisocyanate-diol paste into a mold, characterized in that the wall of the mold is enriched with an organic tin compound, and that said paste has a water content of 0.1 to 1 GewA. UNTERANSPRÜCHE 1. Verfahren gemäss Patentanspruch, dadurch ge kennzeichnet, dass solche Pasten Verwendung finden, welche die Bildung eines Schaumes mit hoher Kerb- zähigkeit gewährleisten. 2. Verfahren nach Unteranspruch 1, dadurch ge- kennzeichnet, dass eine Form aus Silikongummi ver wendet wird. SUBClaims 1. A method according to claim, characterized in that pastes are used which ensure the formation of a foam with high notch toughness. 2. The method according to dependent claim 1, characterized in that a mold made of silicone rubber is used.
CH1498165A 1965-07-20 1965-10-29 Process for the production of polyurethane foam parts with a compact outer skin CH463786A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CH1498165A CH463786A (en) 1965-07-20 1965-10-29 Process for the production of polyurethane foam parts with a compact outer skin

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DEF0046658 1965-07-20
DEF0047091 1965-09-04
DEF0047546 1965-10-28
CH1498165A CH463786A (en) 1965-07-20 1965-10-29 Process for the production of polyurethane foam parts with a compact outer skin

Publications (1)

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CH463786A true CH463786A (en) 1968-10-15

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CH1498165A CH463786A (en) 1965-07-20 1965-10-29 Process for the production of polyurethane foam parts with a compact outer skin

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2049104A1 (en) * 1969-05-16 1971-03-26 Licentia Gmbh
EP1167410A1 (en) * 2000-06-20 2002-01-02 Goldschmidt AG Use of ricinoleic acid in the preparation of polyurethane foams

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2049104A1 (en) * 1969-05-16 1971-03-26 Licentia Gmbh
EP1167410A1 (en) * 2000-06-20 2002-01-02 Goldschmidt AG Use of ricinoleic acid in the preparation of polyurethane foams

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