Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-03-17
2001-02-20
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S128000, C521S129000, C521S174000
Reexamination Certificate
active
06191179
ABSTRACT:
DESCRIPTION
The invention relates to processes for the preparation of foamed plastics based on polyisocyanate polyaddition products by the reaction of isocyanates with isocyanate-reactive compounds having a molecular weight of from 400 to 8000 in the presence of expanding agents, catalysts and optionally chain-extending and/or crosslinking agents having a molecular weight of less than 400, auxiliaries and/or additives, and to foamed plastics based on polyisocyanate polyaddition products which can be produced by this process.
The preparation of foamed plastics based on polyisocyanate polyaddition products, usually polyurethane products and, optionally, polyisocyanura products, by the reaction of isocyanates with isocyanate-reactive compounds in the presence of expanding agents, catalysts and optionally auxiliaries and/or additives has been described in many places. Usually aromatic diisocyanates are used for the preparation of foamed plastics based on polyisocyanate polyaddition products, which aromatic diisocyanates are caused to react with suitable isocyanate-reactive compounds. A drawback occurring in foams prepared in such a manner comprises their tendency to become discolored when exposed to light or when stored and, in the case of some applications, their hydrophobic nature.
Light-fast foamed plastics are usually prepared on the basis of aromatic isocyanates and UV stabilizers. A disadvantage of this is that these UV stabilizers are extremely expensive and are active only for a restricted period. Foamed plastics prepared from aliphatic isocyanates known hitherto are suitable for only very specific applications. WO 89/05830 describes polyurethane networks prepared from polyesterols and lysine diisocyanate. The preparation of such polyurethanes is elaborate however, and impossible for some applications. Polyurethanes based on aliphatic isocyanates are also described in U.S. Pat. No. 4,018,636, U.S. Pat. No. 4,263,070 and U.S. Pat. No. 3,281,378, but these specifications contain no useful teaching on the preparation of expanded polyurethanes.
Optionally expanded polyurethanes based on aliphatic isocyanates are described in EP-A 210,566 and EP-A 275,010. A drawback involved in this technological teaching is the high content of volatile monomeric aliphatic isocyanates (EP-A 275,010) and, respectively, the low content of isocyanate groups (EP-A 210,566) required for the expanding reaction with water.
It is an object of the present invention to provide a process for the preparation of foamed plastics based on polyisocyanate polyaddition products by the reaction of isocyanates with isocyanate-reactive compounds in the presence of expanding agents and catalysts and optionally auxiliaries and/or additives, by means of which foamed plastics can be produced which are not susceptible to discoloration even when stored for relatively long periods under UV irradiation and have a more hydrophilic nature than the foams based on aromatic isocyanates known in the prior art.
This object is achieved in the present invention by the following measures:
i) isocyanates having isocyanurate and/or biuret structures are used, the isocyanate-reactive compounds used are
ii) at least one diol and/or polyol having a molecular weight of from 400 to 8000 and containing at least 50% of primary hydroxyl groups based on all of the hydroxyl groups present in the compound,
iii) at least one compound having at least one primary amine group, and diols and/or triols having molecular weights of less than 400 are optionally used as chain-extending and/or crosslinking agents, the reaction being carried out in the presence of
iv) at least one tertiary amine acting as catalyst and/or
v) at least one metal salt acting as catalyst and
vi) water.
Suitable isocyanates (i) having isocyanurate and/or biuret structures are the aliphatic and/or cycloaliphatic diisocyanates that are known per se which may have been biuretized and/or cyanuratized by generally known processes and exhibit at least one, and preferably at least two, free isocyanate groups and more preferably exhibit three free isocyanate groups. This trimerization trebles the molecular weight of the aliphatic isocyanates and raises their functionality.
The following may be mentioned as specific examples: alkylene diisocyanates containing from 4 to 12 carbon atoms in the alkylene radical such as dodecane-1,12-diisocyanate, 2-ethyltetramethylene-1,4-diisocyanate, 2-methylpentamethylene-1,5-diisocyanate, tetramethylene-1,4-diisocyanate, lysine ester diisocyanates (LDI) and/or hexamethylene-1,6-diisocyanate (HDI); cycloaliphatic diisocyanates such as cyclohexane-[1,3 and 1,4]-diisocyanates and also arbitrary mixtures of these isomers, hexahydrotoluylene-[2,4 and 2,6]-diisocyanates and the corresponding isomer mixtures, dicyclohexylmethane-[4,4′, 2,2′ and 2,4′]-diisocyanates and the corresponding isomer mixtures and/or 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI).
The component (i) used is preferably isocyanuratized and/or biuretized hexamethylene-1,6-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane and/or lysine ester diisocyanate.
The trimerization of isocyanates for the preparation of isocyanates having an isocyanurate structure can be carried out at usual temperatures in the presence of known catalysts, eg phosphines and/or phospholine derivatives, amines, alkali metal salts, metal compounds and/or Mannich bases. Trimerized isocyanates containing isocyanurate structures are, moreover, commercially available.
Isocyanates having biuret structures can be prepared by generally known processes eg by reaction of the said diisocyanates with water or eg diamines, a urea derivative being formed as intermediate. Biuretized isocyanates are also commercially available.
Isocyanates having isocyanurate and/or biuret structures can be used in the process of the invention together with other isocyanates, preferably organic diisocyanates. Suitable other isocyanates are the aforementioned aliphatic and cycloaliphatic diisocyanates and also aromatic diisocycanates and aromatic polyisocyanates such as toluylene-[2,4 and 2,6]-diisocyanate and the corresponding isomer mixtures, diphenylmethane-[4,4′, 2,4′ and 2,2′]-diisocyanates and the corresponding isomer mixtures, mixtures of diphenylmethane-[4,4′ and 2,2′]-diisocyanates, polyphenyl-polymethylene polyisocyanates, mixtures of diphenylmethane-[4,4′, 2,4′ and 2,2′]-diisocyanates and polyphenyl-polymethylene polyisocyanates (crude MDI) and mixtures of crude MDI and toluylene-diisocyanates. Di- and/or poly-isocyanates containing ester, urea, allophanate, carbodiimide, uretdione and/or urethane groups can be used in the process of the invention in addition to the isocyanates having isocyanurate and/or biuret structures as proposed in the invention. Specific examples thereof are urethane group-containing organic polyisocyanates having NCO contents of from 33.6 to 15 wt %, preferably from 31 to 21 wt %, based on the total weight, eg with low-molecular diols, triols, dialkylene glycols, trialkylene glycols or polyether polyalcohols having molecular weights of up to 6000, particularly molecular weights of up to 1500, modified diphenylmethane-4,4′-diisocyanate, modified mixtures of diphenylmethane-[4,4′ and 2,4′]-diisocyanates, modified crude MDI or toluylene-[2,4 or 2,6]-diisocyanate, where the di- or poly-(oxyalkylene glycol)s, which may be used individually or as mixtures, are eg diethylene glycol, dipropylene glycol, polyoxyethylene glycol, polyoxypropylene glycol and polyoxypropylene polyoxyethylene glycol, and the corresponding triols and/or tetrols. Also suitable are NCO group-containing prepolymers having NCO contents of from 25 to 3.5 wt %, preferably from 21 to 14 wt %, based on the total weight, prepared from the polyester polyalcohol and/or, preferably, polyether polyalcohols and diphenylmethane-4,4′-diisocyanate
Chakrabarti Sarbananda
Illguth Rolf
Scherzer Dietrich
Treuling Ulrich
Wagner Klaus
BASF - Aktiengesellschaft
Borrego Fernando A.
Cooney Jr. John M.
LandOfFree
Preparation of polyurethane foams does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Preparation of polyurethane foams, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preparation of polyurethane foams will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2615757