JPH04239582A - Moisture-curable sealing material composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent storage stability and low-temperature curability by using a urethane prepolymer containing free NCO group as a main component and compounding di[2-(2,6-dimethyl morpholino)ethyl] ether as a curing catalyst. CONSTITUTION:The objective composition is produced by using (A) a urethane prepolymer containing 1.5-3W/V% of free NCO group and preferably produced by the reaction of a polyoxyalkylene polyol with an aromatic diisocyanate and compounding the component A with (B) 0.2-2wt.% (preferably 0.4-1.0wt.%) of di[2-(2,6-dimethylmorpholino)ethyl] ether as a curing catalyst.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a moisture-curable sealant composition, more specifically, a moisture-curable sealant composition containing a specific curing catalyst, which can be stored for 1 to 3 months at 40°C in the absence of moisture. The present invention relates to a one-component moisture-curable sealant composition that has good stability and excellent low-temperature curability.

0002

[Prior Art] One-component moisture-curing sealant compositions containing free NCO group-containing urethane prepolymers as a main component are well known, and include adhesives for parts in the automobile manufacturing process, window sealants, etc. Suitable for use in glass bonding, door bonding, etc. Originally, this type of sealant composition can be cured in the presence of moisture (moisture) in the air, but in order to increase work efficiency at construction sites, sealant compositions with a faster curing speed have been developed. A curing catalyst is usually included. However, on the other hand, even when a curing catalyst is blended, storage stability in the absence of moisture must be taken into consideration.

0003

[Problems to be Solved by the Invention] Under such circumstances, metal catalysts and amine catalysts are widely used as curing catalysts, but some of them have problems with storage stability, or cure at room temperature or lower. For example, low temperature curing at 5°C is not sufficient. Recently, as a special catalyst, the formula:

Attempts have been made to use dimorpholino diethyl ether of the following formula (see Japanese Patent Application Laid-open No. 120721/1983). but,
Although this catalyst has no problems with storage stability or room temperature curing, the current situation is that sufficient results cannot be obtained for the above-mentioned low temperature curing.

0004

[Means for solving the problem] Therefore, the present inventors
As a result of extensive research into catalysts that satisfy this low-temperature curing, we discovered that using a specific amount of the methyl-substituted dimorpholinodiethyl ether satisfies both storage stability and room-temperature curing or low-temperature curing. The invention was completed. That is, the present invention
The main component is a urethane prepolymer containing free NCO groups, and 0.2 to 2% by weight of the total composition as a curing catalyst.
The formula:

The present invention provides a moisture-curable sealant composition containing di[2-(2,6-dimethylmorpholino)ethyl]ether of the following formula.

The free NCO group-containing urethane prepolymer used in the present invention can be used without particular limitation as long as it is used as the main component of this type of sealant, but specifically, for example, polyoxyalkylene diol ( polyoxyethylene glycol, polyoxypropylene glycol, polyoxybutylene glycol, or copolymers thereof) or polyoxyalkylene triols (addition polymerization of ethylene oxide, propylene oxide, butylene oxide, etc. with glycerin, trimethylolpropane, etc.) Examples include those obtained by reacting a polyoxyalkylene polyol with an excess amount of an organic diisocyanate compound (aliphatic, cycloaliphatic, arylaliphatic or aromatic diisocyanate) according to a conventional method. The reaction is carried out in an inert gas atmosphere, optionally in the presence of a reaction catalyst (dibutyltin dilaurate, dibutyltin maleate, stannous octate, lead octate, etc.) at a temperature of 50 to 120°C, preferably 60 to 90°C. Just do it.

[0006] Among these urethane prepolymers,
Polyoxypropylene glycol with a molecular weight of 3,000 to 7,000 and an aromatic diisocyanate compound, such as 2,
4 or/and 2,6-tolylene diisocyanate (
A urethane prepolymer having a free NCO group content of 1.5 to 3 w/v% is preferable, which is reacted with TDI), diphenylmethane-4,4'-diisocyanate (MDI), 1,5-naphthalene diisocyanate, xylylene diisocyanate, etc. .

The moisture-curable sealant composition according to the present invention has the above-mentioned urethane prepolymer as the main component and the above formula [
I), but if necessary, fillers (carbon black, calcium carbonate, clay, talc, etc.), which are inert to NCO groups, and plasticizers ( Dioctyl phthalate, butyl benzyl phthalate, dinonyl phthalate, diethylene glycol dibenzoate, ethylene glycol monobutyl ether benzoate, partially hydrogenated terphenyl, alkyl polycyclic aromatic hydrocarbons, chlorinated paraffins, etc.), solvents (toluene, xylene, esters) ethers, ketones, ethers, etc.) may be added in appropriate amounts. Curing catalyst [
The amount of compound I] is selected within the range of 0.2 to 2% by weight, preferably 0.4 to 1.0% by weight based on the total amount of the composition. 0.2
If it is less than 2% by weight, the desired acceleration of curing will not be achieved, and if it exceeds 2% by weight, storage stability will be impaired. Note that, if necessary, it can be used in combination with commonly used metal catalysts, amine catalysts, etc., and can also be used in combination with imidazole compound catalysts.

[0008]

[Examples] Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 and Comparative Examples 1 to 7 (1) Synthesis of urethane prepolymer Polyoxypropylene glycol 30 with a molecular weight of 7000
Add 350g of MDI to 00g and heat at 80℃ under nitrogen atmosphere.
The free NCO group content was 2.3 w/v.
%, a urethane prepolymer having a viscosity (20° C.) of 38,000 cps is obtained.

(2) Preparation of sealant composition (1)
) to 500 g of urethane prepolymer, add 200 g of dried calcium carbonate and 600 g of carbon black,
After stirring and mixing for 10 minutes, add dioctyl phthalate 250
After adding g and performing vacuum degassing stirring under reduced pressure for 15 minutes,
80g of solvent for viscosity adjustment, and 8g of various curing catalysts (
(equivalent to 0.5% by weight of the total composition) and stirred for 10 minutes to remove air bubbles.

(3) Curing test based on low temperature properties Each sealant composition was tested at 5°C/50% RH or at 20°C/65%
After curing for 1 hour, 3 hours or 5 hours under RH conditions, the shear strength (kg/cm2) was measured,
The results are shown in Table 1.

[Table 1] Note *) The curing catalysts used in each example are as follows. Example 1:

[C4] Comparative example 1:

[C5] Comparative Example 2: Dibutyltin dilaurate 3: Dibutyltin maleate 4: Lead octenoate 5: Tin octenoate 6: Triethylamine 7: N-methylmorpholine

(4) Storage Stability Test Each sealant composition was stored under sealed conditions at 40° C. for 1, 2 or 3 months, and then its condition was observed. The results are shown in Table 2. The criteria in the table are as follows. ◎: Viscosity increase rate is 20% or less ○: 〃 is 40% or less △: 〃 is 60% or less ×: 〃 is 60% or more or gelation

[Table 2
] The relationship between the content of the same catalyst as in Example 1, the curing test results based on low temperature characteristics, and the storage stability test results is shown in Table 3 below.
Shown below.

[Table 3]

Claims (2)

[Claims] Claim 1: The main component is a urethane prepolymer containing free NCO groups, and 0.2 to 2% by weight of di[2-(2,6 -dimethylmorpholino)ethyl] ether). 2. The urethane prepolymer is a reaction product of a polyoxyalkylene polyol and an aromatic diisocyanate, and has a free NCO group content of 1.5 to 3.
% w/v. The sealant composition according to claim 1.