JPH06834B2 - Moisture curable resin composition - Google Patents

Description

The present invention relates to a moisture-curable resin composition having excellent storage stability and curability, and more specifically, it has excellent storage stability and curability based on a free isocyanate group-containing polymer. The present invention relates to a moisture curable resin composition.

The resin composition containing as a main component a polymer having at least one free inocyanate group per molecule (hereinafter referred to as “isocyanate polymer”) is a resin composition in which the isocyanate polymer in the composition has, for example, the following reaction formula: : As shown in (4), it is used in a moisture-curable paint or the like by utilizing the fact that it reacts with moisture in the air or the surface to be coated and cross-links and cures. However, such a moisture-curable resin composition has a drawback in that, due to the high reactivity of the free isocyanate group, the crosslinking and curing reaction gradually progresses due to the incorporation of moisture during storage, resulting in thickening or gelation.

Conventionally, in order to improve the storage stability of a moisture-curable resin composition containing such an isocyanate polymer, a tosyl isocyanate, cyclohexyloxycarbonyl isocyanate or an alkyl group having 4 to 18 as a water binder is added to the resin composition. A method of compounding an alkoxycarbonyl isocyanate having 4 carbon atoms (German Patent No. 1,
245,590 and JP-A-52-32946); or carboxylic acid salts of certain amines, C _1-18 fatty acid esters of ascorbic acid or isoascorbic acid, nitrites and nitroparaffin. A method of adding an active methylene compound of one kind, a C _1-8 aliphatic or aromatic anhydride, or a pentahalogenated phenol (Japanese Patent Publication No. 42-16290); tetramethylthiuram disulfide or dibenzyl tetrasulfide. A method of blending a polysulfide compound such as that described in JP-A-57-1475.
11 publication) and the like have been proposed.

However, these stabilizers conventionally proposed are often poor in volatility, and when a resin composition containing the stabilizer is applied to the surface to be coated, the stabilizer remains in the coating film without volatilization. There are drawbacks such as a decrease in the curing rate of the composition and a bad influence on the performance of the coating film.

Therefore, as a result of intensive studies on the stabilizer having no such drawbacks, the present inventors have found that a certain diketal compound has a storage stability in a moisture-curable resin composition containing an isocyanate polymer. Therefore, the present invention has been completed and the present invention has been completed.

Thus, according to the present invention, free isocyanate groups are
In a moisture-curable resin composition containing a polymer having at least one polymer per molecule, that is, an isocyanate polymer, In the formula, R ₁ , R ₂ , R ₃ and R ₄ each independently represent a lower alkyl group, and the diketal compound represented by the formula is contained in an amount of 0.1 to 50 parts by weight per 100 parts by weight of the above isocyanate polymer. A moisture-curable resin composition having excellent storage stability and curability is provided.

In the above formula (I), the "lower alkyl group" may be any type of straight chain or branched chain, and is 1 to 6
It may contain one, preferably one to four carbon atoms. Specific examples of such lower alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, se
Examples include c-butyl and tert-butyl. Also,
The lower alkyl groups represented by R ₁ , R ₂ , R ₃ and R ₄ may all be the same or may be different from each other.

Then, as the diketal compound of the above formula (I),
For example, 2,2-dimethoxypropane, 2,2-diethoxypropane, 2,2-dipropoxypropane, 2,2
-Diisopropoxypropane, 2,2-dibutoxypropane, 2,2- (tert-butoxy) propane 2,2-dimethoxybutane, 2,2- or 3,3-dimethoxypentane, 2,2- or 3, 3-dimethoxyhexane, 3,
3- or 4,4-dimethoxyheptane, 4,4-dimethoxyoctane, 5,5-dimethoxynonane, 2,2-diethoxybutane, 2,2- or 3,3-diethoxypentane, 2,2- or 3,3-diethoxyhexane, 3,3
-Or 4,4-diethoxyheptane, 4,4-diethoxyoctane, 5,5-diethoxynonane, 2,2-dipropoxybutane, 2,2- or 3,3-dipropoxypentane, 2,2 -Or 3,3-dipropoxyhexane,
3,3- or 4,4 dipropoxyheptane, 4,4-dipropoxyoctane, 5,5-dipropoxynonane,
2,2-dibutoxybutane, 2,2- or 3,3-dibutoxypentane, 2,2- or 3,3-dibutoxyhexane, 3,3- or 4,4-dibutoxyheptane,
4,4-dibutoxyoctane, dibutoxynonane, 2-
Methoxy-2-ethoxypropane, 2-methoxy-2-
Propoxypropane, 2-methoxy-2-butoxypropane, 2-ethoxy-2-propoxypropane, 2-ethoxy-2-butoxypropane, 2-propoxy-2-
Butoxypropane, 2-methoxy-2-ethoxybutane, 2-methoxy-2-propoxybutane, 2-methoxy-2-butoxybutane, 2-ethoxy-2-propoxybutane, 2-ethoxy-2-butoxybutane, 5methoxy. -5-Ethoxynonane, 5-methoxy-5-propoxynonane, 5-methoxy-5-butoxynonane and the like are included, and 2,2-dimethoxypropane is particularly preferable.

On the other hand, the isocyanato polymer capable of improving the storage stability by using the diketal compound as described above is at least one, preferably 2 per one molecule of the free isocyanate group at the terminal and / or side chain of the main chain. There is no special limitation as long as it is a polymer having 30 to 30 and capable of forming a cross-linked and cured film by reacting with moisture in the air or the surface of an object to be coated,
Isocyanate polymers, which include any isocyanate polymer and are conventionally used in moisture-curable coating resin compositions, can also be used in the present invention. Some examples of such isocyanate polymers are given below.

(A) Isocyanate group-excess adduct of diisocyanate compound and polyol (urethane prepolymer) Examples of the diisocyanate compound that can be used for forming the adduct include diphenylmethane-4,4'-diisocyanate, tolylene diisocyanate, and hexadiamine. Methylisocyanate, xylylene diisocyanate, isophorone cyisocyanate 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,
4- (or -2,6-) diisocyanate, 1,3-
(Isocyanatemethyl) cyclohexane, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, lysine diisocyanate and the like can be mentioned.

As the polyol, various polyether polyols, polyester polyols, acrylic polyols, epoxy polyols can be used, and typical ones thereof are shown below. (B) Polymer of diisocyanate compound For example, pentamer of tolylene diisocyanate (Desmodur IL manufactured by Bayer), copolymer of 3 mol of tolylene diisocyanate and 2 mol of hexanemethylene diisocyanate (Desmodur EL manufactured by Bayer), hexamethylene A buret (Desmoduy N manufactured by Bayer Co.) containing 3 mol of diisocyanate and 1 mol of water can be used.

(C) In addition, an isocyanate group excess adduct of the polymer of the diisocyanate compound of the above (B) and the polyol described in the above (A) can also be used.

Isocyanate polymers such as those mentioned above are generally 300 to 1
Those which can have a number average molecular weight in the range of 00,000, preferably 500 to 50,000, and which are usually liquid, are preferred.

The above diketal compound is such an isocyanate polymer 1
0.1-50 parts by weight per 00 parts by weight, preferably 1-30
It can be used within the range of parts by weight.

The resin composition of the present invention basically comprises two components of the above-mentioned isocyanate polymer and diketal compound, and further contains a curing accelerator, a pigment, a solvent, a filler, a plasticizer, etc., if necessary. It can be blended.

Examples of the curing accelerator that can be used to give the resin composition an appropriate moisture curing rate include, for example, triethylenediami, N, N, N ', N'-tetramethyl-1,3-butanediamine, Tertiary amines such as N, N, N ′, N ″, N ″ -pentamethyldiethylenetoamine and 1,2,4-trimethylpiperazine; carboxylic acid metal salts such as tin octoate, iron octoate and lead octoate A carboxylic acid organometallic salt or the like, or a combination thereof, for example, 3
Combinations of primary amines and tin dimonocarboxylates are mentioned, which are usually 0.001 to 10 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight of isocyanate polymer, depending on the desired curing rate. Used within the range of.

As the pigment, for example, titanium white, carbon black, red iron oxide, cyanine blue, sinker red,
Color pigments such as quinacridone red, farad red, permanent red, cyanine green, chrome green, ocher, titanium yellow, and fast yellow; metal powder pigments such as aluminum powder, gold powder, stainless steel powder, copper powder and nickel powder; talc , Extenders such as calcium carbonate, mica, clay, white carbon, and barium carbonate.

Examples of the solvent include aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate; general inert solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and these are usually isocyanate. It is used in an amount of 300 parts by weight or less per 100 parts by weight of the polymer.

The plasticizer can be added for the purpose of imparting flexibility, aging resistance, cold resistance and the like to the coating film, and examples thereof include phthalic acid derivatives such as diisobutyrephthalate and dioctyl phthalate; tricresyl phosphate, Phosphoric acid derivatives such as triphenyl phosphate; diisooctyl adipate,
Fatty acid derivatives such as dibutyl sebacate; epoxy derivatives and the like.

The resin composition of the present invention can be produced by kneading the components described above in an atmosphere containing no moisture, for example, in a dry inert gas atmosphere, according to a usual method.

In the moisture-curable resin composition of the present invention, the diketal compound effectively traps water mixed in the resin composition as a water scavenger (water binder), and the isocyanate polymer thickens or gels during storage. Prevent it from changing over time. However, the resin composition of the present invention has almost no increase in viscosity even after being stored at room temperature for 6 months, and its curability is almost the same as the initial curability. Exert.

Moreover, the diketal compound and a ketone produced by the reaction of the diketal compound with water. Alcohols (R ₃ OH, R ₄ OH) are all low molecular weight and easily volatilize. Therefore, after the resin composition of the present invention is applied to an object to be coated, the residual diketal compound, the ketone and the alcohol are immediately removed. Since it volatilizes, the moisture curability of the resin composition after coating is not substantially affected, and exhibits excellent curability. For example, leaving it at room temperature for several days results in a cured film having good gloss and sharpness. can get.

The resin composition of the present invention is cured at room temperature in air, but may be baked and cured at a temperature of up to about 150 ° C. for 10 to 30 minutes if necessary.

Thus, the resin composition of the present invention is for coating materials, sealing materials,
It can be widely used as an adhesive or the like.

Next, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Examples 1 to 5 and Comparative Examples 1 to 2 (A) 123 parts by weight of diphenylmethane-4,4'-diisocyanate heated and melted at about 50 ° C. was put into a reaction vessel substituted with dry nitrogen gas, and an average molecular weight of about 1 was added to the reaction vessel. Addition product of propylene oxide and glycerin of 4000 (“Adeka Polyaeten G-4000” manufactured by Asahi Denka Co., Ltd.) 90
Add 0 parts by weight, and the content of isocyanate groups at 80 ° C is 3.
An isocyanate polymer was obtained by reacting until it reached 0% by weight.

(B) Isocyanate polymer 8 obtained in (A) above
The mixture was placed in a kneading machine in which 00 parts by weight was replaced with dry nitrogen gas, and 800 parts by weight of titanium white previously dried under reduced pressure was added and hermetically kneaded to obtain an isocyanate polymer preliminary mixture.

(C) Then, in the isocyanate polymer obtained in (A) or the isocyanate polymer premixture obtained in (B), a curing accelerator, dry xylene (solvent) and 2, in the proportions shown in Table 1 below. 2-dimethoxypropane or p
-Toluenesulfonyl isocyanate was kneaded under reduced pressure in a kneading machine replaced with a dry gas to obtain a moisture-curable resin composition.

(D) The resin composition thus obtained was sealed in a closed container, and the stability after storage at 40 ° C. for 10 days and at 20 ° C.
Curing and drying properties after drying at 60% relative humidity for 7 days were measured. The results are shown in Table 2 below.

Claims (1)

[Claims] 1. A moisture-curable resin composition containing a polymer having at least one free isocyanate group per molecule, wherein In the formula, R ₁ , R ₂ , R ₃ and R ₄ each independently represent a lower alkyl group, and the diketal compound represented by the formula is contained in an amount of 0.1 to 50 parts by weight per 100 parts by weight of the polymer. A moisture-curable resin composition having excellent storage stability and curability.