Process for producing rapidly curable cold-setting polyurethane

Details Process for producing rapidly curable cold-setting polyurethane Process for producing rapidly curable cold-setting polyurethane

1995-11-02

1997-11-18

Dean, Ralph H.

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...

528 55, 528 56, 528 58, 528 64, G08G 1832

Patent

active

056888929

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a process for producing a polyurethane coating waterproof material, or waterproofer which is rapidly cured at ordinary temperatures. More particularly, the present invention is concerned with a process for producing a polyurethane coating waterproofer which retains a pot life (a period of time during which coating is possible) suited for, especially, hand coating.


Background Art

The polyurethane coating waterproofer has been employed in a large quantity in various uses such as waterproofing of building rooftops, verandas and corridors, and elastic paving of sports facilities. This polyurethane coating waterproofer is prepared by in-situ mixing together two liquids, i.e., a base composed of an isocyanate-terminated prepolymer obtained by reacting a polyol such as a polyoxypropylene polyol with tolylene diisocyanate (hereinafter referred to simply as "TDI") and a curing agent comprising 4,4'-methylenebis(2-chloroaniline) (hereinafter referred to simply as "MOCA") and a polyoxypropylene polyol as an isocyanate-reacting component and, added thereto, a catalyst such as an organometallic lead and, if desired, a plasticizer, followed by hand coating with the use of a trowel, a spatula or a rake, and curing.
The MOCA employed as the principal isocyanate-reacting component of the curing agent in the conventional method is one of the Specified and Designated Chemical Substances under the MITI/MHW in Japan, thus being problematic in safety, and is solid and highly crystalline at room temperature, thus being poor in dissolution stability in the plasticizer and difficult to handle; nevertheless, it reacts with the isocyanate relatively mildly and can ensure a pot life (a period of time elapsed after the mixing of the two liquids during which the mixture can be applied without causing any trouble, generally defined as the time elapsed after the mixing up until a viscosity increase to one hundred thousand centipoises) particularly required in the use as a waterproofer. Further its use ensures the retention of various properties as prescribed with respect to the urethane coating waterproofer by the Japanese Industrial Standard (JIS-A-6021). Therefore, MOCA is substantially a sole aromatic polyamine crosslinker which can be utilized in the field of this type of waterproofer. Especially in the summertime application, frequent use is made of what is known as a modified MOCA which exhibits a functionality somewhat higher than that of MOCA per se and is modified with aniline so as to have swelling and foaming resistances.
When the above MOCA or modified MOCA is used alone as a curing agent, the drawback is brought about that the period during which the coating is in a plastic state is prolonged in the initial stage of the curing of the coating (around the gelation point), so that during this period the coating is likely to suffer from cracking. Therefore, a curing agent comprising a combination of MOCA with a polyol has been employed in which MOCA is dissolved in a polyoxypropylene polyol capable of dissolving MOCA at a relatively high solubility. The reaction of the polyoxypropylene polyol contained in the curing agent with the isocyanate is slower than that of water or MOCA. Consequently, it is essential to add an organometallic lead catalyst such as lead octoate (lead content: 20%) to the curing agent for the purpose of promoting the reaction between the polyoxypropylene polyol of the curing agent and the isocyanate to thereby prevent foaming. Thus, the organometallic lead catalyst is added in an amount of about 2 parts by weight per 100 parts by weight of the isocyanate-terminated prepolymer during the summertime for the prevention of foaming while it is added in an amount of about 4 parts by weight during the wintertime for the promotion of curing.
Meanwhile, what is known as RIM is in use in the manufacture of automobile parts and the like. In the RIM, a highly reactive two-part urethane material consisting of a curing agent containing highly reactive diethyltoluenedia

REFERENCES:
patent: 3882072 (1975-05-01), Olstowski et al.
patent: 4927901 (1990-05-01), Miyazaki
patent: 4945149 (1990-07-01), Matsumoto et al.
patent: 5049638 (1991-09-01), Matsumoto et al.
patent: 5066761 (1991-11-01), Miyazaki
Polyurethane Handbook, ed. Gunter Oertel, Hanser Publishers, pp. 556-559, 1994.

Affiliated with

Also associated with

Rating

Process for producing rapidly curable cold-setting polyurethane does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for producing rapidly curable cold-setting polyurethane , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing rapidly curable cold-setting polyurethane will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1566437