Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-03-10
2001-03-20
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S589000, C524S590000, C524S839000, C524S840000, C528S044000, C528S059000, C528S060000, C528S085000
Reexamination Certificate
active
06204325
ABSTRACT:
The invention relates to processes for producing compact, transparent polyisocyanate polyaddition products by reacting (a) isocyanates with (b) compounds reactive to isocyanates, if desired in the presence of (c) catalysts and (d) auxiliaires and/or additives. The invention also relates to compact, transparent polyisocyanate polyaddition products which can be produced by this process, and to their use.
Compact polyisocyanate polyaddition products, also termed products below, and their production are well known and have been described many times in the technical literature. These products are increasingly used in markets in which use is usually made of glass, for example as windows or lamp covers in the construction of buildings, automobiles or aircraft. A particular advantage of the plastics compared with glass is their low density and low brittleness, making it possible to save fuel and to reduce the formation of splinters when accidents occur. WO 96/23827, for example, describes compact, transparent polyurethanes for producing windows for buildings, automobiles or aircraft. The products of Wo 96/23827 are produced by reacting cycloaliphatic isocyanates with bifunctional polyols to give an NCO-terminated prepolymer, followed by reaction of the prepolymer with a diamine. Disadvantages of these products are their relatively low hardness of Shore D 80-81 and their large coefficient of thermal expansion.
However, a high level of hardness and a low coefficient of thermal expansion are precisely what is required, in particular in automotive and aircraft construction, for example to avoid damage to the products by scratching.
It is an object of the present invention to develop a process for producing compact, transparent polyisocyanate polyaddition products by reacting (a) isocyanates with (b) compounds reactive to isocyanates, if desired in the presence of (c) catalysts and (d) auxiliaries and/or additives, which is capable of producing products with excellent suitability to replace glass. These products should have, in particular, a high level of hardness and a low coefficient of thermal expansion.
We have found that this object is achieved by using as (b) compounds reactive to isocyanates a mixture (i) which has an average functionality of >3 and an average hydroxyl number of from 300 to 950 mg KOH/g.
According to the invention, the high average functionality, i.e. of the functions which are reactive to isocyanates, of the mixture and its high average hydroxyl number, also termed OHN below, achieve strong crosslinking with the isocyanates in the novel products. This gives the desired high level of hardness and thus scratch resistance of the products. In addition to this, the cross-linking gives the products the desired low coefficient of thermal expansion measured in accordance with DIN 53752 (Method A, with continuous heating).
The mixture (i) preferably has an average functionality of from 3 to 6, particularly preferably from 3.1 to 5. The average OHN of the mixture (i) is preferaby from 400 to 900 mg KOH/g, in particular from 500 to 850 mg KOH/g.
The use in this text of the expression mixture does not imply that the compounds present therein are necessarily in the form of a mixture when brought into contact with the isocyanates, but merely defines the material which is to have the average functionalities and hydroxyl numbers according to the invention.
The mixture (i) used to produce the compact, transparent polyisocyanate polyaddition products is preferably one which has an average functionality of >3 and an average hydroxyl number of from 300 to 950 mg KOH/g and comprises the following components:
from 45 to 99% by weight of a mixture (ii) comprising at least one polyether polyalcohol, where the mixture (ii) has an average functionality of at least 3, preferably from 3.1 to 6, and an average hydroxyl number of from 650 to 950 mg KOH/g, preferably from 700 to 940 mg KOH/g, and
from 1 to 55% by weight of a mixture (iii) comprising at least one polyester polyalcohol, where the mixture (iii) has an average functionality of from 2 to 3 and an average hydroxyl number of from 20 to 200 mg KOH/g.
The polyether polyalcohols present in the mixture (ii) according to the invention may be well known compounds which are produced by known processes, for example by alkoxylating starter materials with alkylene oxides. The preparation may be carried out as an anionic polymerization with alkali metal hydroxides as catalysts, such as sodium hydroxide or potassium hydroxide or with alkali metal alcoholates, such as sodium methylate, sodium ethylate, potassium ethylate or potassium isopropylate, and with the addition of at least one starter molecule which contains from 2 to 8 reactive hydrogen atoms, preferably from 2 to 6 reactive hydrogen atoms, or as a cationic polymerization with Lewis acids as catalysts, such as antimony pentachloride, boron fluoride etherate, etc. or bleaching earth, with one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene radical.
The catalyst is usually removed after the synthesis by acid neutralization, distillation and filtration. The acids used are primarily the two mineral acids hydrochloric acid and/or phosphoric acid, because the equivalence point can be precisely controlled and the technology for removing any excess of acid is simple.
Examples of suitable alkylene oxides for preparing the polyols are tetrahydrofuran, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide, styrene oxide and preferably ethylene oxide and 1,2-propylene oxide. The alkylene oxides may be used individually, alternating in succession or as mixtures. Preference is given to the use of alkylene oxides which give primary hydroxyl groups in the polyol. Particular preference is given to the use of polyols which to complete the alkoxylation have been alkoxylated with ethylene oxide, and therefore have primary hydroxyl groups.
Examples of starter molecules are: water, organic dicarboxylic acids, such as succinic acid, adipic acid, phthalic acid and terephthalic acid, aliphatic and aromatic diamines which have from 1 to 4 carbon atoms in the alkyl radical and are either unsubstituted or N-mono- or N,N- or N,N′-dialkyl-substituted, such as unsubstituted, or if desired mono- or dialkyl-substituted ethylenediamine, diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, 1,3- or 1,4-butylenediamine, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexamethylenediamine, phenylenediamine, 2,3-, 2,4- or 2,6-toluylenediamine and 4,4′-, 2,4′- and 2,2′-diaminodiphenylmethane.
Other possible starter molecules are: alkanolamines, such as ethanolamine, N-methyl- and N-ethylethanolamine, dialkanolamines, such as diethanolamine, N-methyl- and N-ethyldiethanolamine, and trialkanolamines, such as triethanolamine, and ammonia, and also polyhydric alcohols, such as ethanediol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose.
To achieve the average functionality according to the invention, use is preferably made of starter molecules which have a functionality of at least 3. It is possible to include in the mixture (ii) polyether polyalcohols with a lower functionality, but in that case at least one more highly functionalized polyether polyalcohol should be present in the mixture (ii) in amounts such that the average functionality achieves a value according to the invention.
The polyether polyalcohols preferably used in the mixture (ii) are products of addition of ethylene oxide and/or propylene oxide to glycerol, trimethylolpropane, ethylenediamine and/or pentaerythritol individually or in mixtures.
The polyester polyalcohols present in the mixture (iii) according to the invention may be well known compounds which are prepared by known processes. Suitable polyester polyols may, for example, be prepared from organic dicarboxylic acids having from 2 to 12 carbon atoms, preferably aliphatic dicarboxylic acids having from 4 to 6 carbon atoms, and polyhydric alco
Baumann Edwin
Beuermann Ilka Renate
Frei Hans-Peter
Maletzko Christian
Roche Peter
BASF - Aktiengesellschaft
Borrego Fernando A.
Niland Patrick D.
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