JPH1025326A - Two pack type curable polyurethane composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of reducing the amount of diethyltoluenediamine is a curing agent and capable of largely suppressing the increase of the viscosity after the admixture of the two packs by using a main agent component containing a specific polyurethane prepolymer as a main component. SOLUTION: This two pack type curable polyurethane composition comprises (A) a main agent component containing an isocyanato group-terminated polyurethane prepolymer having an isocyanate group content of <=2.7wt.% and obtained by reacting (i) a polyol consisting mainly of a polyoxyalkylenepolyol with (ii) a polyisocyanate, and (B) a curing agent component containing diethyltoluenediamine as an active hydrogen compound. The component (ii) is preferably a tolylenediisocyanate especially containing the 2,4-isomer in an amount of 95%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-part curable polyurethane composition which cures at room temperature and has excellent curability, appearance of the cured film, mechanical strength and heat resistance.

[0002]

2. Description of the Related Art Due to its excellent flexibility, polyurethane elastomers are used for a wide range of building materials such as waterproofing materials, flooring materials, sealing materials, and elastic pavement materials.

[0003] This polyurethane elastomer is usually
It is a two-pack type composition that cures at room temperature and comprises a main component mainly composed of an isocyanate group-terminated polyurethane prepolymer and a curing agent composed of an active hydrogen compound. For use as a waterproofing material, the main component is an isocyanate group-terminated polyurethane prepolymer obtained by the reaction of polyoxypropylene polyol with tolylene diisocyanate, and the main components are polyol and 4,4'-methylenebis (2-chloroaniline). The two-component type comprising a curing agent component is still mainstream at present.

[0004]

The main stream of tolylene diisocyanate used as a conventional raw material of the main component is a 2,4-isomer content of 80%. To keep the viscosity of the polyurethane prepolymer low, the equivalent ratio of tolylene diisocyanate to polyol should be NCO group / OH group = 2
Usually, it is produced in the range of from 2.2 to 2.2, and the isocyanate group content of the polyurethane prepolymer is usually from 3 to 5% by weight.

However, such a polyurethane prepolymer requires a curing agent containing an active hydrogen compound in an amount equivalent to the isocyanate group content, and when an amine compound is frequently used as the active hydrogen compound, the pot life after mixing the two components is increased. Is not enough. In particular, in an environment where the temperature in summer is high, the viscosity increases rapidly and the application work is hindered.

[0006]

The present invention is the following invention which has solved the above-mentioned problems. That is, a main component mainly containing an isocyanate group-terminated polyurethane prepolymer having an isocyanate group content of 2.7% by weight or less obtained by reacting a polyol mainly containing a polyoxyalkylene polyol with a polyisocyanate, and an active hydrogen compound And a curing agent component containing diethyltoluenediamine as a cold-curable two-part curable polyurethane composition.

Hereinafter, the present invention will be described in detail. The polyoxyalkylene polyol used for the main agent of the present invention is usually produced by reacting a polyfunctional initiator with an alkylene oxide. The initiator here is
An active hydrogen compound having an average number of functional groups of 2 or more, specifically, ethylene glycol, dipropylene glycol, butanediol, glycerin, trimethylolpropane, pentaerythritol, bisphenol A and the like.

The alkylene oxide is ethylene oxide,
Propylene oxide, 1,2-butylene oxide, 2,
3-butylene oxide, styrene oxide and the like,
Particularly, propylene oxide or a combination of propylene oxide and ethylene oxide is preferred.

A particularly preferred polyoxyalkylene polyol is a polyoxypropylene polyol in which propylene oxide residues (ie, oxypropylene groups) obtained mainly by using propylene oxide account for 80% by weight or more of all alkylene oxide residues. is there.

The number of hydroxyl groups of the polyol is preferably 2 to 4. In particular, it is 3 or less, most preferably more than 2 and 2.5 or less. If the average number of hydroxyl groups is less than 2, it becomes difficult to increase the molecular weight of the cured coating film, so that the cured product has insufficient mechanical strength. If it exceeds 4, the crosslink density becomes too high, and the elongation performance of the cured product deteriorates.

[0011] If the molecular weight of the polyoxyalkylene polyol is too small, the elongation of the cured product becomes extremely poor, making it unsuitable for use as a waterproof material. However, if the molecular weight of the polyol is too high, the viscosity of the obtained polyurethane prepolymer may increase, and the mechanical strength of the cured product may be insufficient.
It is preferably from 00 to 7,000, and from 500 to 3,
000 is preferable, and 700 to 1,500 is particularly preferable.

As the organic polyisocyanate compound,
Isocyanates such as aromatic, aliphatic, and modified polyisocyanates having an average of two or more isocyanate groups are conceivable. However, from the viewpoint of the viscosity, curability, and mechanical strength of the cured coating film of the polyurethane prepolymer obtained, tris are preferred. Range isocyanates are preferred. 2,4-isomer content of 9
Particularly preferred is tolylene diisocyanate of 5% or more.

The polyurethane prepolymer of the present invention is prepared by mixing a polyol containing a polyisocyanate and a polyoxyalkylene polyol as main components in a nitrogen atmosphere at 80 to 1%.
It is preferable to produce by reacting at 00 ° C. for several hours.

At this time, the equivalent ratio of NCO group / OH group is set to 2.0.
The reaction is preferably performed under the following conditions. This allows
It is easy to make the isocyanate group content of the isocyanate-terminated polyurethane prepolymer 2.7% by weight or less.

By reducing the isocyanate group content of the polyurethane prepolymer to 2.7% by weight or less, the amount of the active hydrogen compound, particularly the amine compound, in the curing agent can be reduced. It can be greatly suppressed. Particularly in the summer season, a sufficient pot life can be maintained, the workability is good, and good results can be obtained in splicing and surface appearance.

As the active hydrogen compound used for the curing agent, diethyltoluenediamine is used. It may be used in combination with a polyol, 4,4′-methylene-bis (2-chloroaniline) or the like. When components having different reactivities are mixed, the balance of the reactivity with the main agent is deteriorated, and the curability tends to be slow. In particular, the curability at low temperatures is deteriorated. From the viewpoint of mixing workability, curability, and mechanical properties, it is particularly preferred to use diethyltoluenediamine alone.

Diethyltoluenediamine is liquid at room temperature, has excellent compatibility with plasticizers and the like, and can be optionally diluted.

The diethyltoluenediamine includes 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine, and is preferably a mixture of both. Toluene-2,
Preferably, 4-diamine is contained in an amount of 70 to 85% by weight. In the case of a mixture containing 70 to 85% by weight of the former having highly active and amino groups having different activities, an appropriate thixotropic property appears in the mixture in the initial stage of curing after mixing with the main component,
It can be applied without dripping even on flat or inclined surfaces.

When the active hydrogen compound in the curing agent component is solely diethyltoluenediamine, the coating film obtained is stronger than when the active hydrogen compound other than diethyltoluenediamine is used in combination. Since the density of urea bonds in the hard segment is high and the degree of reaction completion is high, the mechanical strength retention at 60 to 80 ° C. for a long time can be greatly improved.

The additives mainly incorporated in the curing agent of the present invention are fillers, pigments, catalysts, various stabilizers, plasticizers, solvents and the like. Calcium carbonate, talc, clay,
Examples of the pigment include silica and carbon, and examples of the pigment include inorganic pigments such as chromium oxide and titanium oxide and organic pigments such as a phthalocyanine pigment.

Examples of the plasticizer include dioctyl phthalate, dibutyl phthalate, dioctyl adipate, chlorinated paraffin, and petroleum-based plasticizers. Examples of the solvent include aromatic hydrocarbons such as toluene and xylene and n-heptane and n-heptane.
Examples include aliphatic hydrocarbons such as decane. In addition, organic metals such as tin octylate, tin naphthenate, lead neodecanoate, dibutyltin dilaurate, and zinc octylate may be added to accelerate the curing after coating. Furthermore, stabilizers such as antioxidants, ultraviolet absorbers, and dehydrating agents generally used in polyurethane resins can be blended.

The amount of the additives described above is not particularly limited, but is generally 40 to 80% by weight in the curing agent.

As described above, the two-part waterproofing material according to the method of the present invention has an isocyanate group content of 2.7% by weight as the main component.
Since it is less than the above, the working time is sufficiently long, the workability is good, and the appearance of the coating film is also excellent.

[0024]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples.

[Evaluation] <Amine content> The weight percentage of diethyltoluenediamine in the total amount of the main component and the curing agent component.

<Available time> The time from when the main agent and the curing agent are mixed until the coating operation becomes impossible. 5 ℃, 20 ℃
And measured at 35 ° C.

<Basic physical properties> Mechanical properties of the coating film as measured according to JIS A6021. In the table, E is elongation at break (unit:%), T _s is a tensile strength (unit / kg · c
m ^-2 ), and T _r is the tear strength (unit / kg · cm ^-1 ).

<Heat resistance> Mechanical properties after immersion in hot water at 60 ° C. for 7 days.

A main component of an isocyanate-terminated prepolymer was synthesized using the following polyoxyalkylene polyol and tolylene diisocyanate. Polyol A: a polyoxypropylene diol having a molecular weight of 2,000. Polyol B: a polyoxypropylene diol having a molecular weight of 3,000. Polyol C: polyoxypropylene triol having a molecular weight of 3,000. Polyol D: polyoxypropylene triol having a molecular weight of 4,000.

(Example 1) (Synthesis of main ingredient) 600 g of polyol A and polyol D
To 400 g of the above was added 141 g of tolylene diisocyanate having a 2,4-isomer content of 80% by weight (NCO group / OH group equivalent ratio = 1.80), and reacted at 100 ° C. for 4 hours in a reaction vessel. Group content 2.60% by weight,
A polyurethane prepolymer having a viscosity of 10,500 cP / 20 ° C. was obtained.

(Preparation of curing agent) 58.7 g of diethyltoluenediamine, 600 g of calcium carbonate, 50 g of titanium oxide, 251.3 g of dioctyl phthalate, 30 g of xylene and 10 g of carbon black were charged into a kneader and uniformly mixed.

[0032] were mixed with (waterproof material) the main agent / curing agent 1/1 weight ratio (NCO group / NH ₂ group equivalent ratio = 1. 1), was used as a waterproof material.

(Example 2) (Synthesis of main ingredient) 800 g of polyol B and polyol D
Was added to 200 g of the above, 113 g of tolylene diisocyanate (NCO group / OH group equivalent ratio = 1.90) having a 2,4-isomer content of 100% by weight was reacted in a reaction vessel at 100 ° C. for 4 hours. A polyurethane prepolymer having a group content of 2.28% by weight and a viscosity of 8,500 cP / 20 ° C. was obtained.

(Adjustment of curing agent) 51.4 g of diethyltoluenediamine, 600 g of calcium carbonate, 50 g of titanium oxide, 258.6 g of dioctyl phthalate, 30 g of xylene, and 10 g of carbon black were charged into a kneader and uniformly mixed.

[0035] were mixed with (waterproof material) the main agent / curing agent 1/1 weight ratio (NCO group / NH ₂ group equivalent ratio = 1. 1), was used as a waterproof material.

(Example 3) (Synthesis of main ingredient) 800 g of polyol B and polyol C
Was added to 200 g of the above, 118 g of tolylene diisocyanate having a 2,4-isomer content of 100% by weight (NCO group / OH group equivalent ratio = 1.85), and the reaction was carried out at 100 ° C. for 4 hours in a reaction vessel. A polyurethane prepolymer having a group content of 2.30% by weight and a viscosity of 9,000 cP / 20 ° C. was obtained.

(Preparation of Curing Agent) 51.9 g of diethyltoluenediamine, 600 g of calcium carbonate, 50 g of titanium oxide, 258.1 g of dioctyl phthalate, 30 g of xylene and 10 g of carbon black were charged into a kneader and uniformly mixed.

[0038] were mixed with (waterproof material) the main agent / curing agent 1/1 weight ratio (NCO group / NH ₂ group equivalent ratio = 1. 1), was used as a waterproof material.

Comparative Example 1 (Synthesis of Main Agent) 800 g of polyol A and polyol C
174 g (NCO group / OH group equivalent ratio = 2.0) having a 2,4-isomer content of 80% by weight was added to 200 g of A polyurethane prepolymer having a group content of 3.52% by weight and a viscosity of 7,500 cP / 20 ° C. was obtained.

(Adjustment of curing agent) 67.8 g of diethyltoluenediamine, 600 g of calcium carbonate, 50 g of titanium oxide, 242.2 g of dioctyl phthalate, 30 g of xylene and 10 g of carbon black were charged into a kneader and uniformly mixed.

[0041] were mixed with (waterproof material) the main agent / curing agent 1/1 weight ratio (NCO group / NH ₂ group equivalent ratio = 1. 1), was used as a waterproof material.

Comparative Example 2 (Synthesis of Main Agent) 750 g of polyol A and polyol C
174 g (NCO group / OH group equivalent ratio = 2.0) having a 2,4-isomer content of 100% by weight was added to 250 g of the above, and reacted at 100 ° C. for 4 hours in a reaction vessel. Group content 3.50% by weight,
A polyurethane prepolymer having a viscosity of 87,500 cP / 20 ° C. was obtained.

(Adjustment of Curing Agent) 67.4 g of diethyltoluenediamine, 600 g of calcium carbonate, 50 g of titanium oxide, 242.6 g of dioctyl phthalate, 30 g of xylene and 10 g of carbon black were charged into a kneader and uniformly mixed.

[0044] were mixed with (waterproof material) the main agent / curing agent 1/1 weight ratio (NCO group / NH ₂ group equivalent ratio = 1. 1), was used as a waterproof material.

Comparative Example 3 (Synthesis of Main Agent) 800 g of Polyol A and Polyol C
165 g (NCO group / OH group equivalent ratio = 1.9) having a 2,4-isomer content of 100% by weight was added to 200 g of the resulting mixture, and the mixture was reacted at 100 ° C. for 4 hours in a reaction vessel. Group content 3.20% by weight,
A polyurethane prepolymer having a viscosity of 11,500 cP / 20 ° C. was obtained.

(Preparation of curing agent) 61.6 g of diethyltoluenediamine, 600 g of calcium carbonate, 50 g of titanium oxide, 248.4 g of dioctyl phthalate, 30 g of xylene and 10 g of carbon black were charged into a kneader and uniformly mixed.

[0047] were mixed with (waterproof material) the main agent / curing agent 1/1 weight ratio (NCO group / NH ₂ group equivalent ratio = 1. 1), was used as a waterproof material.

[0048]

[Table 1]

[0049]

As described above, according to the method of the present invention,
By setting the isocyanate group content of the polyurethane prepolymer composed of polyisocyanate and polyoxyalkylene polyol to 2.7% by weight or less, the amount of diethyltoluenediamine used in the curing agent can be reduced.
It is possible to significantly suppress the increase in viscosity after mixing the two components, and it is possible to obtain a sufficient pot life especially in summer.

Claims (3)

[Claims] 1. A main component mainly comprising an isocyanate group-terminated polyurethane prepolymer having an isocyanate group content of 2.7% by weight or less, obtained by reacting a polyol mainly comprising a polyoxyalkylene polyol with a polyisocyanate; A room temperature curable two-part curable polyurethane composition comprising a curing agent component containing diethyltoluenediamine as an active hydrogen compound. 2. The composition of claim 1 wherein the polyisocyanate is tolylene diisocyanate. 3. The composition according to claim 1, wherein the tolylene diisocyanate is a tolylene diisocyanate having a 2,4-isomer content of 95% or more.