JPH04110318A - Urethane prepolymer composition - Google Patents

Abstract

PURPOSE:To improve reactivity and curability at a low humidity and mechanical strengths and durability after curing by reacting a specific polyoxyalkylene polyol with diphenylmethane diisocyanate. CONSTITUTION:One equivalent of a polyoxyalkylene polyol which comprises 20-80wt.% polyoxyalkylene triol having a mol.wt. of 3000 or higher and 80-20wt.% polyoxyalkylene diol having a mol.wt. of 500-5000 and in which 5-20wt.% of oxyalkylene chains are oxyethylene chains, the rest being oxypropylene chains, is reacted with 1.7-2.2 equivalents of diphenylmethane diisocyanate, if necessary in the presence of a reaction accelerator or retarder, at 40-150 deg.C to give an NCO-terminated urethane prepolymer compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyurethane prepolymer composition that has excellent curing properties by reaction with moisture under low humidity conditions, and excellent mechanical properties and durability after curing. .

(Prior art) Conventionally, polyurethane prepolymers having isocyanate groups at the ends, which are obtained by reacting polyoxypropylene polyol and organic polyisocyanate, can be used as a one-component type by reacting with moisture in the atmosphere and curing. It is used in many fields such as adhesives, waterproofing materials, sealing materials, and lining materials because it does not require the trouble of mixing liquids and has excellent adhesion to substrates.

However, this moisture-curable polyurethane prepolymer is slow to cure under low humidity conditions and requires a long time for the cured product to exhibit practical properties.

In order to solve this problem, attempts have been made to copolymerize polyoxyethylene polyol or polyoxyethylene oxypropylene polyol.

However, all of these conventional copolymer compositions have insufficient curability under low humidity conditions, and even when cured under low humidity conditions, the cured products have poor water resistance or lack mechanical properties. However, it had some drawbacks in terms of practicality.

(Problems to be Solved by the Invention) The object of the present invention is to have an isocyanate group at the end of a polyoxyalkylene diol and an organic polyisocyanate reacted with each other, to improve reaction curability under low humidity, and to improve the reaction curability after curing. An object of the present invention is to provide a polyurethane prepolymer composition having mechanical strength and durability of .

(Means for Solving the Problems) The present inventors have conducted extensive research to solve the above problems, and as a result, have completed the present invention.

That is, the present invention relates to a polyurethane prepolymer having an isocyanate group at the end obtained by the reaction of a polyoxyalkylene polyol and diphenylmethane diisocyanate, in which the polyoxyalkylene polyol is (A) a polyoxyalkylene triol having a molecular weight of at least 3,000. (B) a polyoxyalkylene diol having a molecular weight of at least 3,000, based on 20 to 8 of the total polyol;
(C) The oxyalkylene chain consists of an oxyethylene chain and an oxypropylene chain, and (D) The oxyethylene chain accounts for 5 to 20% by weight of the total oxyalkylene chain. A polyurethane prepolymer composition.

(Structure) The polyoxyalkyl non-triol of the present invention is usually obtained by ring-opening addition of alkylene oxide to a triol such as glycerin, ) and limethylolbroban, and has a molecular weight of 3,000 or more, preferably 5,000 to 15,000.
It is. If the molecular weight is less than 3000, the cured product will have poor mechanical strength, particularly tear strength.

The polyoxyalkylene diol of the present invention is usually obtained by ring-opening addition of an alkylene oxide to a diol such as ethylene glycol, diethylene glycol, fluoropylene gellicol, or dipropylene glycol, and has a molecular weight of preferably 500 to 5000. 1000 to 30
It is 00. If the molecular weight is less than 500, the cured product will have poor mechanical strength, particularly elongation, while if it exceeds 3000, the cured product will have poor tensile strength.

The polyoxyalkylene polyol of the present invention contains 20 to 8 polyoxyalkylene triols in the total polyol.
Must contain 0% by weight.

When the polyoxyalkylene triol is less than 20% by weight, the physical properties of the cured product are slow to develop, while when it is more than 80% by weight, the mechanical strength, particularly the tear strength, of the cured product is poor.

In the polyoxyalkylene polyol of the present invention, the oxyalkylene chain consists of an oxyethylene chain and an oxypropylene chain, and there are 5 oxyethylene chains in all the oxyalkylene chains.
It should be between 1% and 20% by weight, preferably between 10 and 18% by weight. If the polyoxyethylene chain content is less than 5% by weight, curability under low humidity conditions will be poor, while if it exceeds 20% by weight, the cured product will have poor water absorption, particularly water swelling at low temperatures, such as 5°C. The polyoxyethylene chain may be present in either the polyoxyalkylene triol or the polyoxyalkylene diol, but it is preferably present in both.

The polyurethane prepolymer composition of the present invention is produced by a conventional urethanization reaction. That is, polyoxyalkylene polyol and diphenylmethane diisocyanate are mixed in the presence or absence of a reaction accelerator or reaction retardant for 40 minutes.
React at 150°C to 150°C. The diphenylmethane diisocyanate is used in an excess amount relative to the polyoxyalkylene polyol at a ratio of -1.7 to 2.2. The polyoxyalkylene triol and polyoxyalkylene diol may be mixed in advance and reacted with diphenylmethane diisocyanate, or may be reacted separately and then mixed.

The polyurethane prepolymer of the present invention may contain solvents, process oils, plasticizers, thixotropic agents, fillers, stabilizers,
A catalyst etc. may be mixed. Examples of the solvent include toluene, xylene, turpentine, ethyl acetate, butyl acetate, methyl ethyl ketone, and cellosolve acetate. Process oils include high boiling point oils obtained through petroleum refining. Examples of the plasticizer include dibutyl phthalate and dioctyl phthalate. Examples of the thixotropic agent include polyvinyl chloride powder, finely powdered silica, and bentonite. Examples of the filler include carbon black, calcium carbonate, talc, clay, silica, and titanium oxide. Examples of the stabilizer include antioxidants and ultraviolet absorbers. Examples of the catalyst include tertiary amines and organometallic compounds.

(Effects of the Invention) The polyurethane prepolymer composition of the present invention has excellent reaction curability at low humidity, so it can be reactively cured in a short time even at low humidity and low temperature such as in winter, and has excellent mechanical properties after curing. , adhesives, waterproofing agents, etc. due to their excellent durability.
It is useful for sealing materials, linings, etc.

(Examples) Next, examples will be shown, but the present invention is not limited only to these examples. "Parts" and "%" in the text are based on weight unless otherwise specified.

In addition, physical properties of the cured films in Examples were measured as follows.

[Strength and elongation J: Measured according to J15A6021.

"Water swelling property" = Swelling property was observed after immersion in water for 17 days at 5°C12O°C.

Examples 1-5 and Comparative Examples 1-2 The polyoxyalkylene triol shown in Table 1 remains as is. reason. . .

@+ tl-, l+-Yang secret gun yaiya t++V+-'+T-'-1-U4, yo J?
a? Weir diol and polyoxyalkylene diol were mixed, toluene was added so that the concentration of the resulting polyurethane prepolymer was 90% by weight, 1% by weight, diphenylmethane diisocyanate was added, and the mixture was reacted at 80°C for 8 hours under a nitrogen stream. Example 5
and Comparative Examples 1-2).

The viscosity (poise) and inner atom group content (wt%) of this polyurethane prepolymer solution at 25°C
) are shown in Table 1. 0.05 parts of dibutyltin dilaurate was mixed with 100 parts of this polyurethane prepolymer solution, and the mixture was left in an atmosphere of 5° C. and 20% relative humidity for 20 hours to observe the degree of hardening. In addition, the physical properties of the cured film were measured, and the results are shown in Table 2.

Agent: Patent Attorney Katsutoshi Takahashi

Claims (1)

[Scope of Claims] 1. A polyurethane prepolymer having isocyanate groups at the terminals obtained by the reaction of a polyoxyalkylene polyol and diphenylmethane diisocyanate, wherein the polyoxyalkylene polyol is (A) a polyoxygenate having a molecular weight of at least 3,000; an alkylene triol and a polyoxyalkylene diol having a molecular weight of 500 to 5000, (B) a polyoxyalkylene triol having a molecular weight of at least 3000 in an amount of 20 to 80% by weight based on the total polyol; A polyurethane prepolymer composition comprising an ethylene chain and an oxypropylene chain, characterized in that (D) the oxyethylene chain accounts for 5 to 20% by weight based on the total oxyalkylene chain.