JPS5978227A - Urethane prepolymer composition - Google Patents

Abstract

PURPOSE:The titled one-component moisture-curable composition having excellent storage stability, undergoing no foaming when stored in an atmosphere of high temperature and humidity, and having an adjustable curing rate, containing an excess of tolylene diisocyanate and an excess of diphenylmethane 4,4'-diisocyanate. CONSTITUTION:A urethane prepolymer X is prepared from a polyol mixture containing (A) a polyalkylene ether triol having three hydroxyl groups, average MW of 5,000-7,000, and (B) a polyalkylene ether diol having two hydroxyl groups, average MW of 1,000-4,000, and an excess of tolylene diisocyanate. Another urethane prepolymer Y is obtained from the polyol mixture containing the above polyalkylene ether triol (A) and the above polyalkylene ether diol (B) and an excess of diphenylmethane 4,4'-diisocyanate. The titled composition is obtained by mixing the above urethane prepolymers X and Y together.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a one-component moisture-curable urethane prepolymer composition that has excellent storage stability, does not foam even under high temperature and high humidity conditions, and has an adjustable curing speed. In addition,
This urethane prebomer can be used as a sealant (for example, a sealant for automobiles, a sealant for buildings), a waterproofing material, a flooring material, and the like.

Conventionally, urethane sealant compositions are polyol-based and
It was a two-component product consisting of an isocyanate system. This two-component urethane sealant composition does not generate gas when cured, and therefore foaming can be controlled relatively easily. Furthermore, since the polyol type and isocyanate type can be stored separately, storage stability is excellent. However, because it is a two-component type, (1) it is necessary to measure each of the two components during on-site construction, (2) it is necessary to stir and mix the two components after measurement, and (3) there is no air pollution during stirring and mixing. It has drawbacks such as the need to avoid contamination (bubbles). In order to overcome these drawbacks, one-component urethane sealants using moisture curing have been proposed.
In the publication, triol (average molecular weight 4500) 1
Moles and diols (average molecular weight 2000) A prepolymer consisting of 5 moles of mixed polyol and diphenylmethane-4,4'-diisocyanate is disclosed.

However, this liquid-based urethane sealant composition has the following drawbacks: (1) It easily foams under high temperature and humidity;
(2) It has problems such as easy gelation during storage.

In general, liquid moisture-curable urethane sealing materials tend to foam during curing because carbon dioxide gas is generated by the reaction between free isocyanate in the urethane prepolymer and moisture during the curing reaction. . Since foaming is more likely to occur under high temperature and humidity conditions or in high temperature water, there is a strong desire to develop a sealing material that promotes hardening without foaming properties.

In particular, one-component moisture-curing urethane sealants used in automobiles that have come off the production line at automobile production plants are not completely cured. In this state, a shower ring test is conducted, and if the sealant is stored outdoors with some water attached to the sealant, or if it is stored outdoors during rainy weather in the summer, foaming is likely to occur. become. Under such circumstances, for example, 40°C
There is a need for a one-component moisture-curing urethane sealant that does not foam during curing under harsh conditions in hot water.

Therefore, as a method for suppressing the foaming properties of liquid moisture-curable urethane sealants, a method has been proposed that uses, for example, a urethane prepolymer made of an aromatic diisocyanate that has a reactivity equivalent to that of a trifunctional or higher-functional polyol. (Japanese Patent Application Laid-Open No. 54-126297). That is, according to this method, foaming can be suppressed by using a urethane prepolymer consisting of polypropylene ether triol having three hydroxyl groups and having an average molecular weight of 7,000 and diphenylmethane-4,4'-diisocyanate.

However, this urethane prepolymer has drawbacks such as high viscosity and storage stability.

The present invention was made in view of the above-mentioned circumstances, and
It is an object of the present invention to provide a one-component moisture-curable urethane prepolymer composition that does not have the above-mentioned drawbacks.

In order to achieve this objective, the present inventors conducted various studies and found that a urethane precipitate was used in a mixed system of polyoxypropylene triol and polypropylene ether diol using diphenylmethane-4,4'-diisocyanate (hereinafter referred to as MDI). Plasticizers are generally added to reduce the degree of formation of higher-order polyfunctionalization during polymerization reactions and to reduce the viscosity of urethane prepolymers, but polyoxypropylene triol and polyoxypropylene ether diol We found that the prepolymer obtained when a urethane prepolymerization reaction is carried out using tolylene diisocyanate (hereinafter referred to as TDI) in a mixed system can be used as a reactive plasticizer, and we have come to form the present invention. .

Therefore, the urethane prepolymer composition of the present invention has
Urethane prepolymer (X) and urethane prepolymer (
Y), the urethane prepolymer (X) consists of a polyalkylene ether triol (A) having three hydroxyl groups and an average molecular weight of 5,000 to 7,000 and a polyalkylene ether diol (B) having two hydroxyl groups and an average molecular weight of 1,000 to 4,000. It consists of a mixed polyol mixed with
Y) is characterized in that it consists of a mixed polyol obtained by mixing the polyalkylene ether triol (A) and the polyalkylene ether diol (B) described above, and an excess of MDI.

Hereinafter, the configuration of the present invention will be explained in detail.

The polyalkylene ether triol (hereinafter simply referred to as triol) used in the present invention has three hydroxyl groups and has an average molecular weight of 5,000 to 7,000.

Preferably, it has a molecular weight of 5,500 to 6,500, and any commercially available products may be used, such as those based on polyoxypropylene triol, glycerin, and trimethylolpropane. If the average molecular weight exceeds 7000, the total unsaturation degree will increase and the average number of functional groups will decrease as a result, making it difficult for the resulting urethane prepolymer composition to exhibit its performance as a sealing material, making it impractical.

Furthermore, if the average molecular weight is less than 5,000, the resulting urethane prepolymer composition will have a high viscosity, an increase in hardness, and a decrease in elongation as a sealing material, which is not practical.

Further, the polyalkylene ether diol (hereinafter simply referred to as diol) used in the present invention is, for example, polypropylene ether diol, which has two hydroxyl groups and has an average molecular weight of 1000 to 4000, preferably 1500 to 3.
000.

As with triols, the viscosity of the resulting urethane prepolymer composition decreases as the average molecular weight of diols increases. When the average molecular weight exceeds 4000, the total unsaturation degree increases, resulting in a decrease in the average number of functional groups,
It becomes difficult to obtain performance as a sealing material. On the other hand, when the average molecular weight is less than 1000, the viscosity becomes high and it becomes impractical.

It should be noted that these triols and diols may be modified to have terminal hydroxyl groups in order to improve the reactivity and performance of the resulting urethane prepolymer composition as a sealing material. Furthermore, in order to improve the physical properties as a sealing material, a small amount of polyoxyalkylene glycol such as polyoxyethylene glycol, polyoxytetramethylene glycol, or polyalkylene ether polyol having four or more functional groups may be used in combination.

Urethane prepolymer (X), which is one component of the urethane prepolymer composition of the present invention, is obtained by mixing a triol and a diol, adding an excess of TDI to the mixture, and reacting the mixture. The mixing ratio of triol and diol depends on the viscosity of the resulting urethane prepolymer composition,
From the viewpoint of the balance of storage stability, curing speed, physical properties, etc. as a sealing material, it is preferable that the molar ratio of triol/diol is 1/3 to 3/1.

Moreover, in consideration of the curing speed, physical properties, etc. as a sealing material, it is preferable that -i of the urethane prepolymer (X) is 50% by weight or less of the total prepolymer. If it exceeds 50% by weight, the curing speed as a sealant will be slow, making it impractical.

There are two types of TDI: 2.4-TDI and 2.6-TDI, and generally a mixture of the two is used, but any mixing ratio can be used. Note that a small amount of other polyisocyanates may be used in combination to improve the sealing material.

Further, the urethane prepolymer (Y), which is another component constituting the urethane prepolymer composition of the present invention, is obtained by mixing a triol and a diol, adding an excess of MDI to the mixture, and reacting the mixture. The mixing ratio of triol and diol is preferably 1 mol to 3 mol of triol per 1 mol of diol, from the viewpoint of preventing foaming and developing physical properties of the resulting urethane prepolymer composition. Less than 1 mole of triol causes foaming problems;
If it exceeds 3 moles, the viscosity becomes high and is not practical. MDI
There are crude MDI, pure MDI, and liquid MDI (pure MD
Although there are modified products of I), hydrogenated-MDI, etc., it is preferable to use pure-MDI and liquid-MDI in the present invention. and a urethane prepolymer (Y), but in order to make this urethane prepolymer composition, an excess of TDI; In preparing the urethane prepolymer composition, dibutyltin dilaurate, dibutyltin maleate, stannous octate, octenoic acid may be reacted by adding excess MDI and triol and diol. A reaction promoting catalyst such as lead can be used.

In order to impart desired physical properties, viscous properties, etc. to the sealant, fillers inert to isocyanate groups, plasticizers, solvents, curing accelerating catalysts, etc. are mixed with the urethane prepolymer composition. It's okay. Examples of fillers include carbon blank, clay, talc, calcium carbonate, white carbon, silicic anhydride, or mixtures thereof, and plasticizers include 7-thalic acid derivatives such as dibutyl phthalate and dioctyl phthalate, as well as tetrahydro-7 Derivatives such as tarlic acid, azelaic acid, maleic acid, trimellitic acid, isophthalic acid, adipic acid, itaconic acid, citric acid, etc., aromatic hydrocarbons such as toluene and xylene as solvents, and triethylenediamine as catalyst for curing , pentamethylene diethylene triamine, morpholine amines, amine catalysts such as triethylamine, diptyltin dilaurate, tin octylate, zinc octylate.

Metal catalysts such as metal soaps are used.

Examples and comparative examples are illustrated below.

Examples 1-5. Comparative Examples 1 to 3 57 parts by weight of polyoxypropylene triol having 3 hydroxyl groups and having an average molecular weight of 5000 and 23 parts by weight of polypropylene ether diol having 2 hydroxyl groups and having an average molecular weight of 2000 were placed in a reaction vessel and heated to 110°C! 50t
After dehydrating under reduced pressure in rvnHg for 2 hours, it was cooled to 80°C.
To this, 2.4-) lylene diisocyanate and 2.6-
Mixture of tolylene diisocyanate (80:20)
9.1 parts by weight was added with stirring and allowed to react until the free incyanate content became 2.2% to obtain a TDI prepolymer (urethane prepolymer (3)). Next, 40 parts by weight of previously dehydrated dioctyl phthalate and 196 parts by weight of diphenylmethane-4,4'-diisocyanate were added to this TDI prepolymer and stirred. 35 parts by weight of polypropylene ether diol having an average molecular weight of 2000 was added and reacted at 80°C until free isocyanate became 18% to obtain an MDI prepolymer (urethane prepolymer (Y)) to obtain a urethane prepolymer composition. Ta. The molar ratio 2 weight ratio of each prepolymer is shown in Table 1 below.

Next, 100 parts by weight of the obtained urethane prepolymer composition was put into a kneading machine container filled with dry nitrogen gas, and 10 parts by weight of dehydrated dioctyl phthalate, 85 parts by weight of dry carbon black, and 10 parts by weight of dry calcium carbonate were added.
Throw in the weight department! Thoroughly kneaded under reduced pressure After each component was uniformly dispersed, a mixture of 8 parts by weight of dehydrated xylene and 0.3 parts by weight of dibutyltin dilaurate was further added, thoroughly kneaded under reduced pressure, and the desired A one-component moisture-curing urethane sealant was created (Example 1).
.

Similarly, triol, diol, TDI.

Urethane prepolymer compositions were obtained by changing the MDI combinations as shown in Table 1, and sealing materials were created (Examples 2 to 5 and Comparative Examples 1 to 3).

Foaming test for these sealants.

A curing rate test and a storage stability test were conducted. These results are shown in Table-1.

(Margins below this page) (Note) Mura Foamability Test: A bead of sealant with a diameter of 10 mm was placed on a glass plate with a thickness of 5 mm, a width of 25 mm, and a length of 14 mm, and the bead of sealant was placed so that the thickness was 5 WrrI. The specimen is pressed uniformly onto the surface of the substrate, and immediately immersed in a thermostatic water bath controlled at 40° C.±2° C. for 72 hours, and the foaming during curing is observed.

Yellow 2 curing speed test: Based on tack free time at 20°C and 65% relative humidity. 100 minutes or less is preferable.

Storage stability test 3: The storage stability test referred to here is an accelerated deterioration test in which a sealant is placed in a sealable container and left in an atmosphere of 50°C for 5 days, and the evaluation is performed using a Matsuku Michael viscometer. The rate of change in viscosity after deterioration relative to the initial viscosity of the sealant is determined. Storage stability is viscosity change rate, 50%
The following was considered acceptable, and 40% or less was considered good.

As described above, the one-component moisture-curing urethane sealant using the urethane prepolymer composition of the present invention has the advantage that it has excellent foaming control and storage stability even under high temperature and high humidity, and that the curing speed can be adjusted. have. Therefore, the urethane prepolymer composition of the present invention can be used in various applications such as automobile wind sealants, thermal one-component moisture-curing roof waterproofing materials, architectural sealants, and the like.

Claims (1)

[Claims] Urethane prepolymer (X) and urethane Brevo 177-
(Y), the urethane prepolymer (X) is a polyalkylene ether triol (A) having three hydroxyl groups and an average molecular weight of 5,000 to 7,000, and a polyalkylene ether diol having two hydroxyl groups and an average molecular weight of 1.000 to 4,000. (B) and an excess of tolylene diisocyanate, and the urethane prepolymer (Y) is a mixture of the above polyalkylene ether triol (A) and the above polyalkylene ether diol (B). A bovine tamp 1 novel polymer composition comprising a mixed polyol and an excess of diphenylmethane-4,4'-diisocyanate.