JPS6337806B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel moisture-curing polyurethane composition that has excellent storage stability and does not reduce the curing speed during construction. R(-S
) _-o A composition comprising a polysulfide compound represented by R' is added. Water-curable moisture-curing urethane compositions used for sealing, adhesion, coating, etc. are usually composed of polyoxy(low) alkylene polyols (triol, triol and diol, tetrol, etc.) and organic diisocyanates (tolylene diol, etc.). Isocyanate, diphenylmethane
The basic component is an isocyanate group-terminated polyurethane prepolymer made of a reaction product with 4,4'-diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, etc.), and further contains curing physical property modifiers, extenders, workability modifiers, etc. It is what was done. When this composition is used in industrial applications such as the automobile assembly industry, architectural applications, etc., the composition is required to have an appropriate moisture curing speed, and in order to meet this requirement, it is necessary to add a moisture reaction catalyst. The catalyst for the reaction between the isocyanate group and water used for this purpose is triethylenediamine,
Tertiary compounds such as N,N,N',N'-tetramethyl-1,3-butanediamine, N,N,N',N'',N'',-petanemethyldiethylenetriamine, 1,2,4,-trimethylpiperazine, etc. Amines, carboxylic acid metal salts, carboxylic acid organic metal salts, etc. are known as active catalysts, and in particular, the combination of tertiary amines and tin dimonocarboxylic acid salts can be used in moisture-curing compositions for industrial use due to their synergistic effect. Provides advantageous accelerated hardening properties. However, when these highly active catalysts are used, even when moisture is prevented from entering the composition,
The drawback is that storage causes an undesirable increase in viscosity and gelation of the composition. Therefore, in order to obtain storage stability of such polyurethane compositions having free isocyanate groups, conventionally, in general, (1) addition of the above-mentioned cured physical property modifiers, extenders, workability modifiers, etc. or (2) reduce the water content as much as possible before the effect of the organic diisocyanate is applied to them, or Monoisocyanates such as group or aliphatic oxycarbonyl isocyanates are used as ice binders to reduce the water content in the composition, or (3) amines are Carboxylate salts, fatty acid esters of ascorbic acid or isoascorbic acid with C18 or less, active methylene compounds such as nitriles, nitroparaffins, acetoacetic esters, malonic acid esters, aliphatic or aromatic acid anhydrides with C18 or less Alternatively, the addition of pentahalogenated phenol or the like is carried out to minimize the urethane bonding of free isocyanate groups in the urethane composition during storage or the reaction between free isocyanates. Examples of using blocking agents that are volatile at room temperature are disclosed in Canadian Patent No. 722,764, US Pat. No. 3,779,794, and the like. However, when monoisocyanates are used among these stabilizers, they react with moisture and produce by-products that interfere with the reaction between the original isocyanate groups and water, resulting in delayed moisture curing. The drawback is that the thixotropic properties of the composition are severely reduced during storage. Also,
When tertiary amines, carboxylic acid metal salts, or mixtures thereof are incorporated as catalysts, the above-mentioned phenolic or acid ester stabilizers and active methylene compounds reduce the curing rate of the composition, especially when the active methylene In the case of compounds, storage further reduces the curing speed and is not very effective in preventing increases in viscosity of the composition. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a moisture-curable polyurethane composition that does not have the above-mentioned drawbacks and has excellent storage stability. The present inventors have proposed the addition of polysulfide compounds in moisture-curing polyurethane compositions that use tertiary amines, carboxylic acid metal salts, or mixtures thereof as catalysts and exhibit advantageous moisture-curing properties in industrial and architectural applications. It was discovered that the above-mentioned drawbacks of the conventional stabilizers can be solved by the above-mentioned stabilizers, and the present invention was developed. Therefore, the moisture-curable polyurethane composition of the present invention is composed of a reaction product of an organic compound having at least two active hydrogens and an organic polyisocyanate, and is selected from the group consisting of tertiary amines and carboxylic acid metal salts. contains at least one selected compound as a reaction catalyst between an isocyanate group and water, and has the formula R(-S)- _o R' (in the above formula, n≧2, R and R' are an isocyanate group (representing any same or different groups) which are inert to
It is characterized by containing 0.5 to 10 parts by weight. Hereinafter, the configuration of the present invention will be explained in detail. The reaction product of an organic compound having at least two active hydrogens and an organic polyisocyanate (hereinafter referred to as urethane prepolymer) constituting the moisture-curable polyurethane composition of the present invention is a conventional polyurethane prepolymer having free isocyanate groups. Any known urethane prepolymer may be used. In addition, when a moisture-curable polyurethane composition is mainly used as a sealing material, a sealing adhesive, an adhesive sealing material, an adhesive, a coating material, etc. in the industrial field or the architectural field, the release of the urethane prepolymer in the composition The isocyanate content is 0.2-1.5% by weight. As the organic polyisocyanate, aromatic diisocyanates and aliphatic diisocyanates such as diphenylmethane-4,4'-diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, etc. can be used singly or in combination. Organic compounds having at least two hydrogen atoms that are active toward isocyanate groups include polyoxy(low)alkylene polyols (triols, tetraols,
pentols and mixtures thereof or with diols) are common. However, these are not particularly limited. Furthermore, the method for producing the urethane prepolymer is not particularly limited, and any method well known to those skilled in the art may be employed. Furthermore, in the present invention, as in conventional moisture-curing polyurethane compositions, at least one compound selected from the group consisting of tertiary amines and carboxylic acid metal salts is used as a reaction catalyst between isocyanate groups and water. use. These compounds may also be conventionally known compounds and are not particularly limited. In the present invention, for example, triethylenediamine, N,N,N',N'-tetramethyl-1,3-butanediamine, N,N,N',
N″,N″-pentamethyldiethylenetriamine,
Tertiary amines such as dimethylbenzylamine and 1,2,4-trimethylpiperazine, monocarboxylic acid salts of tin, iron, zirconium, zinc, lead, etc., or a mixture of these tertiary amines and metal monocarboxylic acid salts system is used. The amount to be blended is determined depending on the intended use of the composition, but generally it is preferably 10 parts by weight or less per 100 parts by weight of the urethane prepolymer. In the present invention, a polysulfide compound having the following formula is used as a stabilizer. R(-S) _-o R' In the above formula, n≧2 (preferably, 6≧n
≧2), R and R' represent the same or different groups that are inert to isocyanate groups. This compound is represented by, for example, the following (1) to (18).

【table】

【table】

[Table] Among these compounds, compounds (1) to (4), namely bis-(3-[triethoxysilyl]-propyl)-tetrasulfide, dixylyl disulfide, tetramethylthiuram disulfide, and tetraethylthiuram disulfide are preferably used. In addition, those which are liquid at room temperature are particularly preferable, and particularly bis-(3-[triethoxysilyl]-propyl)-tetrasulfide exhibits a high effect, so it is particularly preferable to use this. The blending amount is preferably 0.5 to 10 parts by weight per 100 parts by weight of the urethane prepolymer, and preferably 1.0 to 6 parts by weight from the viewpoint of effective economic efficiency. Moreover, one kind or two or more kinds of the above compounds can be used. As described above, the moisture-curable polyurethane composition of the present invention is composed of a urethane prepolymer, a reaction catalyst, and a polysulfide compound. It can be changed by adding other compounding agents. The amount and type of compounding agents to be mixed will depend on the intended use of the composition, but useful compounding agents include carbon blacks such as furnace black and thermal black, and those with isocyanate groups such as talc, silica, calcium carbonate, and titanium oxide. Inert filler (usually urethane prepolymer 100%
50 to 300 parts by weight) General inert plasticizers such as phthalate esters such as dioctyl phthalate and diisodecyl phthalate, chlorinated paraffins, and benzoic acid esters such as ethylene glycol monobutyl ether benzoate (usually urethane resin) 150 parts by weight or less per 100 parts by weight of polymer), aromatic solvents such as toluene and xylene, general inert solvents such as esters and ketones (usually 15 parts by weight or less per 100 parts by weight of urethane prepolymer), etc. be. In addition, organic and inorganic inert colorants can also be used. As explained below, the moisture-curable polyurethane composition of the present invention uses a polysulfide compound as a stabilizer. Therefore, according to the present invention,
The disadvantages of conventional storage stabilizers, which are that increasing the amount to increase storage stability, reduce the curing speed, reduce the curing speed during storage, and have low storage stabilization ability are improved. be. In the present invention, the reason why the use of polysulfide compounds exhibits the effect of preventing thickening is not clear, but polysulfide compounds have the effect of decreasing the activity of the catalyst when moisture is blocked, and restoring the activity when moisture arrives. It is thought that the Examples are illustrated below. Examples 1 to 19 82 parts by weight of diphenylmethane-4, which was heated and melted at about 50°C in a reaction vessel purged with dry nitrogen gas.
Add 4′-diisocyanate and add polyoxypropylene triol 600 with an average molecular weight of about 6000.
parts by weight were added and reacted at 80°C until the content of isocyanate groups was 2.9% by weight, and then stannous di(2-ethylhexoate) (tin content 28
%) in dry toluene and continue the reaction until the isocyanate content is 1.9% by weight. Then, cool to room temperature,
Obtain a urethane prepolymer. 100 parts by weight of this urethane prepolymer was placed in a kneading machine purged with dry nitrogen gas, and under reduced pressure, 90 parts by weight of furnace thermal black, 10 parts by weight of calcium carbonate, and diisodecyl were dried to a moisture content of 0.06% by weight or less. Add 10 parts by weight of phthalate and knead in a closed container. Next, a catalyst, a dry solvent, and a polysulfide compound are added in the respective amounts shown in Table 1, and the mixture is kneaded under reduced pressure to obtain various moisture-curable urethane compositions. Next, the urethane composition was sealed in a sealed container, and the Mack Michael viscosity (20°C, 20 RPM, No. 4 notch, No. 18 wire) before and after storage at 40°C for 10 days and the relative humidity at 20°C and 60% were measured. Table 2 shows the results of measurement of the curing speed (tack free time). In addition, Mack Michael viscosity and tack-free time are measured by the following method. [] Mac Michael viscosity measurement method Take the composition whose temperature has been adjusted to 20°C into the large cup attached to the Mac Michael Visosimeter, taking care not to introduce air bubbles.
Then, insert a 1 cm diameter plunger connected to the spindle into the composition up to the No. 4 notch, rotate the cup at 20 RPM, and take the reading after 10 seconds as the viscosity (°M). The wire connected to the spindle is No. 18 wire. [] Tack-free time measurement method: Pour the composition at a temperature of 20°C onto an iron plate for about 10 mm.
Apply in a bead shape with diameter x 100mm length. At regular intervals, a polyethylene film of 0.5 mm thickness x 10 mm width x 100 mm length is placed on the bead at right angles to the bead length direction, and a 10 x 10 mm film weighing 5 g is placed on top of the bead at right angles to the bead length direction.
A weight is placed on the bead, and the polyethylene film is immediately peeled off at 90 degrees to the bead surface, and the time required for the composition to stop adhering to the polyethylene film after being applied to the bead is determined.

【table】

[Table] *2 Dixyl disulfide

【table】

[Table] Example 20 Polyoxypropylene triol 300 with an average molecular weight of 3000 was placed in a reaction vessel purged with dry nitrogen gas.
parts by weight and 51 parts by weight of 2,4-/2,6-tolylene diisocyanate (80/20) were added and reacted at 95°C until the isocyanate content was 3.1% by weight, and then cooled to room temperature to react with urethane. Obtain a prepolymer. 100 parts by weight of this urethane prepolymer was placed in a kneading machine purged with dry nitrogen gas, and 100 parts by weight of furnace thermal black was dried under reduced pressure to a moisture content of 0.06% by weight or less.
20 parts by weight of calcium carbonate was added and kneaded in an airtight manner.
Next, 0.06 parts by weight of triethylenediamine, 0.6 parts by weight of tin octoate, 2 parts by weight of xylene, and 3 parts by weight of bis-(3-[triethoxysilyl]-propyl)-tetrasulfide were added, kneaded under reduced pressure, and then placed in a closed container. The viscosity before and after storage at 40℃ for 10 days and at 20℃ by the method described above is 60%.
Curing speed at relevant humidity (tack free time)
was measured, and the following results were obtained. Viscosity before storage 26゜M Viscosity after storage 30゜M Tack-free time before storage 80 minutes Tack-free time after storage 76 minutes

Claims (1)

[Scope of Claims] 1. Contains at least one compound selected from the group consisting of tertiary amines and carboxylic acid metal salts as a reaction catalyst between an isocyanate group and water, and has the formula R(-S) _-o A polysulfide compound having R' (in the above formula, n≧2, R and R' represent the same or different groups that are inert to isocyanate groups).
A moisture-curable polyurethane composition comprising a reaction product of an organic compound having at least two active hydrogens and an organic polyisocyanate, containing 0.5 to 10 parts by weight.