JPH11140422A - One pack type moisture-curable urethane sealant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a one pack type moisture-curable urethane sealant composition having good storage stability. SOLUTION: This one pack type moisture-curable urethane sealant composition comprises (a) a urethane prepolymer obtained by allowing a mixture of a polyethertriol with a polyetherdiol each having a number-average mol.wt. of 1,000-7,000 to react with 4,4'-diphenylmethanediisocyanate in an NCO group/OH group equivalent ratio of 1.1-2.5, (b) a dimorpholinodiethyl ether compound of the formula [(n) is 0 or 1] in an amount of 0.05-0.18 wt.% based on the sealant composition as a catalyst and (c) heavy calcium carbonate having an average particle diameter of 1.0-3.2 μm in an amount of 2-20 wt.% based on the sealant composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-part moisture-curable urethane sealant composition for use as a sealing agent, an adhesive, a coating agent and the like for automobiles, buildings and structures, and more particularly, to a composition having a high curing rate. The present invention relates to a one-pack moisture-curable urethane sealant composition which has no adhesion failure at the time of accelerated curing by a catalyst, has excellent storage stability in the absence of moisture, and has sufficient curability with moisture in the atmosphere.

[0002]

2. Description of the Related Art Hitherto, various urethane compositions utilizing moisture curing have been proposed, and are used in the field of automobiles, such as bonding of a vehicle body and a window glass, or in the field of construction, and furthermore, for example, in the case of metal-to-metal. It is used in various fields as a structural adhesive to be bonded. A moisture-curable urethane composition is usually blended with a tertiary amine-based and / or metal carboxylate-based curing catalyst, and the curing speed is adjusted by selecting the type and amount of the curing catalyst.

On the other hand, from the viewpoint of storage stability and sufficient curability, it has been found that blending of dimorpholinodiethyl ether (DMDEE) as a curing catalyst for urethane prepolymers is not disclosed.
No. 75035, and DMDEE
The use of di [2- (3,5-dimethylmorpholino) ethyl] ether as a catalyst has also been proposed in Japanese Patent Publication No. 7-8982.

[0004]

However, the present inventors have proposed a dimorpholino diethyl ether compound as a catalyst having storage stability in the absence of moisture and sufficient curability in the presence of atmospheric moisture. However, if the curing speed is improved only by increasing the amount of the catalyst, there is a problem in that when cured in a one-component urethane-accelerated curing environment such as high temperature and high humidity, a problem occurs in the adhesion between the primer and the sealant. I found that.

Accordingly, the present invention solves the problem of poor adhesion at the time of accelerated curing by using dimorpholino diethyl ether or a derivative thereof as a catalyst, and has a good storage stability and a sufficient amount of moisture in the atmosphere. An object of the present invention is to provide a one-part moisture-curable urethane sealant composition that cures.

[0006]

According to the present invention, (a)
A mixture of polyether triol and polyether diol having a number average molecular weight of 1,000 to 7000
-Diphenylmethane diisocyanate with NCO group / OH
A urethane prepolymer reacted so that the equivalent ratio of the groups becomes 1.1 to 2.5, (b) a content of 0.05 to 0.18% by weight as a catalyst in the sealant composition, formula (I) :

[0007]

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Wherein the content of the dimorpholino diethyl ether compound represented by the formula (m is 0 or 1) and (c) the sealant composition is 2 to 20% by weight, and the average particle size is 1.0 to 10%. There is provided a one-part moisture-curable urethane composition comprising 3.2 μm of heavy calcium carbonate.

[0009]

According to the present invention, as described above, a mixture of polyethertriol and polyetherdiol is used as an isocyanate compound having excellent curability,
4'-diphenylmethane diisocyanate is converted to an NCO group /
A urethane prepolymer reacted so that the equivalent ratio of OH groups becomes 1.1 to 2.5, and heavy calcium carbonate having an average particle diameter of 1.0 to 3.2 μm for imparting deep curability. 2 to 20% by weight, preferably 3 to 15% by weight of the sealant composition, and 0.05 to 0.18% by weight of the dimorpholino diethyl ether compound of the formula (I) as a catalyst in the sealant composition. %, Preferably 0.0
A moisture-curable urethane sealant having sufficient adhesion to the primer, excellent storage stability, and sufficient curability can be obtained by blending in an amount of 8 to 0.14% by weight even in a high-temperature and high-humidity environment. Was found.

The urethane prepolymer to be incorporated into the sealant composition of the present invention is a known substance, for example, a polyether triol such as a polyoxypropylene triol having three hydroxyl groups per molecule and having a number average molecular weight of about 5000, A desired urethane prepolymer can be obtained by reacting a mixture with a polyether diol such as a polypropylene ether diol having a number average molecular weight of about 2,000 having two hydroxyl groups per molecule and 4,4'-diphenylmethane diisocyanate.

The curing catalyst used in the present invention is a dimorpholino diethyl ether compound represented by the above formula (I).
It is publicly known as described in Japanese Patent Publication No. 5035 and Japanese Patent Publication No. 7-8982. The amount of the catalyst is 0.05 to 0.18% by weight, preferably 0.08 to 0.14% by weight, based on the weight of the sealant composition. If the amount is too small, sufficient curability cannot be obtained. On the contrary, if the amount is too large, there is a possibility that an adhesion failure may occur under the high-temperature and high-humidity curing condition, which is not preferable.

According to the present invention, as described above, 2 to 20% by weight, preferably 3 to 15% by weight of heavy calcium carbonate having an average particle size of 1.0 to 3.2 μm is contained in the sealant composition. Mix.

The average particle size of the heavy calcium carbonate is 1.0
If it is less than μm, the storage stability in the absence of moisture becomes poor,
On the other hand, if the thickness exceeds 3.2 μm, the smoothness of the sealant may be impaired, which is not preferable. According to the present invention, it is preferable to add heavy calcium carbonate, as described above, to impart so-called "deep hardening property". Here, the deep curability means a speed represented by the thickness of a film formed with respect to time under moisture.

In order to impart desired physical properties and the like, the composition of the present invention may further contain a filler, a plasticizer, a solvent, and the like inert to isocyanate groups. For example, as the filler, carbon black, clay, talc or the like or a mixture thereof is mentioned, as the plasticizer, phthalic acid derivatives such as dibutyl phthalate and dioctyl phthalate, tetrahydrophthalic acid,
Derivatives such as azelaic acid, maleic acid, trimellitic acid, isophthalic acid, adipic acid, itaconic acid, and citric acid, and examples of the solvent include aromatic hydrocarbon solvents such as toluene and xylene.

The method for producing the sealant composition of the present invention is not particularly limited, but the components other than the curing catalyst and the solvent are sufficiently kneaded under reduced pressure, uniformly dispersed, and then the curing catalyst is mixed with a solvent such as xylene. And kneading the mixture under reduced pressure to form a composition.

[0016]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited to these Examples.

EXAMPLE 1 A polyether triol average molecular weight of about 5,000 and a polyether diol average molecular weight of about 2,000 were mixed at a weight ratio of 6/4, dehydrated at 110 ° C., and the molten 4,4′-diphenylmethane diisocyanate was mixed with NCO groups / OH An amount that gave an equivalent ratio of 1.7 to the group was added, and the mixture was stirred and stirred at 80 ° C. in a nitrogen atmosphere for 36 hours to obtain a prepolymer (A). Dioctyl phthalate, carbon black and heavy calcium carbonate are added as plasticizers to the prepolymer (A) thus obtained, mixed under a vacuum for 1 hour, and then diethyl malonate is added as a catalyst and a stabilizer. And further mixed for 10 minutes to obtain a sealant composition.

Example 2 As shown in Table I, 0.10% by weight of dimorpholino diethyl ether (manufactured by Huntsman) was used as a catalyst, and various calcium carbonates (A) to (E) were blended to obtain eight types. And the appearance storage stability, adhesiveness, and shear strength were measured. The results are shown in Table I.

[0019]

[Table 1]

Evaluation method 1) Storage stability 50 ° C., viscosity increase rate after standing for 2 weeks [%] 2) Adhesion 50 ° C., 95% RH, adhesion by curing for 3 days CF: Cohesive failure of adhesive layer PS : Interfacial fracture between primer and celite 3) Shear strength Strength after curing at 20 ° C, 65% RH for 24 hours [MPa]

Example 3 As shown in Table II, three types of catalysts were used, and calcium carbonate (A) was blended as shown in Table II to obtain nine types of sealant compositions, and their storage stability. , Adhesion and shear strength were evaluated. The results are shown in Table II.

[0022]

[Table 2]

As described above, the urethane sealant of the present invention has no poor adhesion during accelerated curing due to the addition of a large amount of a dimorpholino diethyl ether compound, has good storage stability in the absence of moisture, and has a high moisture content in the atmosphere. Sufficient curability can be obtained only by its presence.

 ──────────────────────────────────────────────────の Continuing from the front page (72) Eiji Nishi Inventor 2-1 Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Co., Ltd. Hiratsuka Factory

Claims (1)

[Claims] (1) a number average molecular weight of 1,000 to 700
Urethane prepolymer obtained by reacting 4,4'-diphenylmethane diisocyanate with a mixture of a polyether triol and a polyether diol such that the equivalent ratio of NCO groups / OH groups is 1.1 to 2.5. (B) a content of 0.05 as a catalyst in the sealant composition;
~ 0.18% by weight of formula (I): Wherein n is 0 or 1; and (c) a content of 2 to 20% by weight in the sealant composition,
A one-pack moisture-curable urethane composition comprising heavy calcium carbonate having an average particle size of 1.0 to 3.2 μm.