Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Patent
1991-01-09
1992-06-23
Welsh, Maurice J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C08G 1812
Patent
active
051244250
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a curable composition which is curable at room temperature to present a cured product having a low modulus and high elongation and which is useful as sealing material or waterproof material.
BACKGROUND ART
A polyurethane prepolymer having terminal isocyanate groups is used for a one-pack type composition curable by reaction with moisture in the air and for a two-pack type composition curable by being mixed with an active hydrogen compound. Such a one-pack type or two-pack curable composition is widely used in the field of building materials or construction materials, such as sealing materials, waterproof materials or floor materials. Reflecting diversification of building and construction fashions in recent years, sealing materials and waterproof materials having higher flexibility and elongation are desired.
In order to obtain a cured product having flexibility and high elongation by a curable polyurethane composition, it is common to employ a method of using a polyoxyalkylenepolyol having a high molecular weight, or a method wherein the content of a bifunctional polyoxyalkylenepolyol is increased so that the average number of functional groups of the polyoxyalkylenepolyol component is decreased. However, such methods have drawbacks that the curing speed tends to be slow, and the tackiness of the cured products tends to increase, and they failed to provide satisfactory properties.
DISCLOSURE OF INVENTION
The present inventors have conducted extensive researches to solve the above mentioned problems and as a result, have found it possible to obtain a cured product having flexibility and high elongation without lowering the curing speed or without increasing the tackiness, by using as a polyoxyalkylenepolyol component a polyoxyalkylenepolyol having a molecular weight per hydroxyl group within a range of from 1,500 to 15,000 and a total unsaturation degree of at most 0.07. Namely, the present invention presents the following curable composition useful as sealing material or waterproof material: component a polyurethane prepolymer having terminal isocyanate groups obtained by reacting an organic polyisocyanate and a polyol comprising as the main component a polyoxyalkylenepolyol having a molecular weight per hydroxyl group of from 1,500 to 15,000 and a total unsaturation degree of at most 0.07 meq/g.
The polyoxyalkylenepolyol having a molecular weight per hydroxyl group within a range of from 1,500 to 15,000 and a total unsaturation degree of at most 0.07 to be used in the present invention, can be prepared usually by means of a catalyst such as zinc diethyl, iron chloride, a metal porphyrin or a double metal cyanide complex. It is not advisable to use a usual alkali catalyst such as KOH, since the unsaturation degree tends to be high, particularly with a high molecular weight product. It is preferred to employ a double metal cyanide complex catalyst.
It is known to use a double metal cyanide complex such as cobalt zinc cyanide-grime as a catalyst for producing a polyoxyalkylenepolyol. Such a double metal cyanide complex catalyst is disclosed in e.g. EP283148 and in the following U.S. Patents:
For the production of the polyoxyalkylenepolyol having a high molecular weight and a low unsaturated degree in the present invention, it is preferred to employ a double metal cyanide complex catalyst as disclosed in the above references. Such a catalyst is believed to have a structure of the following formula (1). Mn(II), Cr(III), Cu(II), Sn(II), Pb(II), Mo(IV), Mo(VI), W(IV) or W(VI), M' is Fe(II), Fe(III), Co(II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), Ni(II), V(IV) or V(V), R is an organic ligand, and each of a, b, x and y is a positive integer variable depending upon the valence and the coordination number of metals, and each of c and d is a positive integer variable depending upon the coordination number of metals.
In the formula (1), M is preferably Zn(II), and M' is preferably Fe(II), Fe(III), Co(II) or Co(III). The organic ligand may, for example, be a
REFERENCES:
patent: 4721818 (1988-01-01), Harper et al.
Higuchi Toshihiko
Kozawa Sigeyuki
Kunji Nobuaki
Asahi Glass Company Ltd.
Welsh Maurice J.
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