JPH0813829B2 - Alkoxysilyl group-containing azo compound and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel alkoxysilyl group-containing azo compound and a method for producing the same, more specifically, a polymer produced when used as a polymerization initiator. The present invention relates to an alkoxysilyl group-containing azo compound capable of introducing an alkoxysilyl group that contributes to cross-linking into its molecular chain, and a method for producing the same.

[Conventional technology]

Conventionally, azo compounds have been used as a polymerization initiator for causing radical polymerization. On the other hand, a polymer compound having an alkoxysilyl group has been used as a crosslinkable organic polymer because it is crosslinked by moisture in the air or the like.

In the production of an alkoxysilyl group-containing polymer, that is, in the polymerization, (a) a method of copolymerizing a compound having an alkoxysilyl group as a raw material monomer, (b) a method of using a compound having an alkoxysilyl group as a chain transfer agent, and ( c) A method of adding a compound having an alkoxysilyl group to a polymer that has already been synthesized has been carried out.

The method using copolymerization of (a) is disclosed in JP-B-51-28301, and the method using a compound having an alkoxysilyl group as a chain transfer agent of (b) is disclosed in JP-A-47- No. 4192, a method of introducing an alkoxysilyl group by the addition reaction of (c) is disclosed in JP-B-45-11819.

[Problems to be Solved by the Invention]

An object of the present invention is to provide an alkoxysilyl group-containing azo compound having one azo group in one molecule and one trialkoxysilyl group or dialkoxysilyl group on each residue on both sides of the azo group, and to prepare the same. A polymerization initiator capable of initiating radical polymerization and introducing an alkoxysilyl group capable of contributing to crosslinking in a polymer molecular chain when providing a method and performing radical polymerization of one or more vinyl polymerizable monomers To provide.

[Means for solving the problem]

The alkoxysilyl group-containing azo compound intended in the present invention has, in one molecule, both an azo group which is weak to heat and an alkoxysilyl group which is weak to moisture in the presence of an acid or a strong alkali. Therefore, it has been very difficult to find a method for synthesizing such an azo compound containing an alkoxysilyl group.

However, as a result of diligent studies, the present inventors have found that if an isocyanate having an alkoxysilyl group in the molecule and an azo compound having a hydroxyl group in the molecule are used as raw materials, both the azo group and the alkoxysilyl group are damaged. It was found that the target compound can be synthesized by a mild reaction without the presence of the compound, and the compound synthesized by this method actually functions as a polymerization initiator, and the produced polymer is produced in the presence of water. It was confirmed that a rubber elastic body having a high gel fraction was obtained by crosslinking, and the present invention was accomplished.

The alkoxysilyl group-containing azo compound of the present invention is represented by the following general formula (I).

(In the formula (I), X is an alkoxy group having 1 to 4 carbon atoms, and examples of X include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, and an n-butoxy group. However, only one of these may be bonded to Si, or two or three of these may be mixed and bonded to Si. X may be different in the residues on both sides of the azo group.

Further, in the formula (I), n represents 2 or 3. R ¹
Represents H or an alkyl group having 1 to 4 carbon atoms, and is composed of a methyl group according to a specific example. R ² represents a dimethylene group or a trimethylene group, and a trimethylene group is used according to a specific example.

The method for producing an alkoxysilyl group-containing azo compound of the present invention is represented by the formula (II); An alkoxysilyl group-containing isocyanate represented by the formula (wherein X, n, R ¹ and R ₂ have the same contents as those described for the formula (I)), and a formula (III); And a hydroxyl group-containing azo compound represented by

That is, an alkoxysilyl group-containing isocyanate represented by the formula (II) and a hydroxyl group-containing azo compound represented by the formula (III) are mixed, and a catalyst is further mixed if necessary, in a solution state or in the formula (III). The reaction proceeds in a suspension state in which a part of the compound is left undissolved.

A tertiary amine such as N, N-dimethylethylamine or N, N, N ', N'-tetramethyl-1,3-propanediamine is effective as a catalyst to be mixed if necessary.

The important use of the alkoxysilyl group-containing azo compound represented by the above formula (I) is as a radical polymerization initiator having an ability to introduce an alkoxysilyl group into a produced polymer, particularly into a vinyl polymer. is there.

[Action]

Since the alkoxysilyl group-containing azo compound of the present invention has an azo group, when a polymer is produced by a polymerization method such as solution polymerization or bulk polymerization using a vinyl polymerizable monomer such as an acrylic ester as a main raw material. It can be used in the same manner as a conventional radical polymerization initiator.

Further, since the alkoxysilyl group is introduced into the polymer composition obtained as described above, the polymer is given the ability to be crosslinked by the action of moisture such as moisture in the air.

In the alkoxysilyl group-containing azo compound of the present invention, contrary to the above, the reaction of the alkoxysilyl group can be used first. That is, an azo group is introduced on the surface of the inorganic material by using it in the same manner as the silane coupling agent. An organic material grafted with an organic polymer can be obtained by immersing the thus surface-treated organic material in a monomer and causing polymerization by the action of heat or the like.

[Explanation of Example]

 Examples of the present invention will be described below.

Synthesis of azo compound containing alkoxysilyl group Formula (Ia); A compound represented by, that is, 2,2'-azobis (2-
The synthesis was performed using (N- (3-trimethoxysilylpropyl) carbamooxymethyl) propionnitrile) as a target.

As a starting material, formula (IIa); and _{(CH 3 O-) 3 Si- (} CH 2) 3 alkoxysilyl group-containing isocyanate represented by -NCO, i.e., 3-trimethoxysilylpropyl isocyanate, formula (III); A hydroxyl group-containing azo compound represented by, that is, 2,2'-
Azobis [2- (hydroxymethyl) propionnitrile] was used.

When the melting point of the compound of the formula (III) was measured at a rate of 4 to 5 ° C. per minute by using a microscope-type melting point measuring device, there was a melting region in the range of 145 to 146 ° C.

Hereinafter, the compounds represented by the above formulas (1a), (IIa) and (III) are respectively referred to as compound (I) and compound (II
a) and compound (III).

1.61 g (0.3 mol) of compound (IIa), compound (II
19.6 g (0.1 mol) of I) and 20 g of methyl ethyl ketone and 20 g of ethyl ether as a solvent,
The mixture was placed in a 0 ml Erlenmeyer flask and placed in an ice bath while stirring in suspension.

The liquid temperature in the Erlenmeyer flask could be confirmed with a thermometer. After the liquid temperature dropped to 5 ℃, N, as a reaction catalyst,
0.8 grams of N'-dimethylethylamine was added. The reaction was continued for 4 hours from the time when the reaction catalyst was added, and then the stirring was stopped. On the way, the liquid temperature rose to 7 ° C. (about 40 minutes after adding the reaction catalyst), but did not become higher than that. The suspension was left to stand overnight (about 16 hours) until the next step.

The suspension obtained was then suction filtered through a glass filter and the precipitate was washed with about 60 ml of ethyl ether.

The washed precipitate was spread on filter paper and left for about 2 hours to remove volatiles.

The obtained product was white fine powder, and the yield was about 13 g. Assuming the product to be compound (Ia), the yield based on compound (III) was about 21%.

The product was identified by various methods. Less than,
Various identification results will be described using this product as a sample α.

Melting point The melting point of the sample α was measured using a microscope-type melting point measuring device. The rate of temperature increase was 4 to 5 ° C. per minute. Sample α
Had a melting region of 118-119 ° C.

As a result of performing the measurement on the same sample, it became to melt at a lower temperature, and reproducibility was not recognized. this is,
It is presumed that decomposition is occurring in part.

Molecular Weight Measurement The freezing point depression of sample α in benzene was measured.
A mercury bar thermometer with a scale interval of 0.1 ° C. was used for the measurement.

The measured freezing point of benzene alone was 5.51 ° C, whereas the measured freezing point of the 0.4 wt% benzene solution of sample α was 5.47 ° C, and a freezing point depression of 0.04 ° C was observed.

However, since there is no error of ± 0.01 ° C in freezing point depression, when the value is set to 0.03 to 0.05 ° C and the molar freezing point depression coefficient of benzene is calculated as 5.12, the molecular weight of sample α is
That is between 441 and 735. It can be seen that the compound (Ia) has a molecular weight of 606.8 in this molecular weight range.

Element quantitative analysis The quantitative determination of each element of C, H, N and Si in the sample α was performed by requesting a measurer who did not know the identity (synthesis procedure, estimated chemical structure, etc.) of the sample. Of these, each of C, H, and N was measured by collecting CO ₂ , H ₂ O, and N ₂ generated by burning the sample.

Further, Si was quantified by decomposing the sample with a mixed solution of nitric acid and fluorine, and then subjecting the sample to an emission spectrometer using high frequency induction plasma.

The results are shown in the first display below. As is clear from Table 1, the weight fraction of each element in the sample α is in good agreement with the theoretical value of the compound (Ia).

Ultraviolet absorption analysis The results of ultraviolet absorption analysis of sample α are shown in FIG.

The measurement was carried out by placing a solution prepared in ethanol at a concentration of 0.005 mol / l in a quartz glass cell having an optical path length of 1 cm.

As is clear from FIG. 1, the peak centered at 343 nm is considered to indicate the presence of an azo group. Its molar extinction coefficient is 16 l / mol, and it can be seen that it is almost comparable to the measured value for existing azo compounds (13 l / mol for compound (III)).

Infrared absorption analysis A chart of infrared absorption analysis for sample α is shown in FIG. In the second figure, characteristic absorption of NH groups in 3050～3400Cm ^-1 is characteristic absorption of CH ₂ groups in 2800 to 3000 cm ^-1 is the characteristic absorption of -C = N in the vicinity of 2250 cm ^-1, 1400 cm around ^-1 , 1560 cm around ^-1, 1680 cm ^-1 and 1730cm characteristic absorption of the urethane bond in the vicinity of ^-1, 1360 cm ^-1 and 1450cm characteristic absorption based around ^-1 CH ₂ -CH ₃ is, Si in the vicinity of 600～720Cm ^-1 Characteristic absorptions based on (CHO ₃ ) ₃ groups are observed respectively.

Nuclear magnetic resonance analysis Sample α was made into a solution having a concentration of 0.5% by weight in CD ₃ OD, and H-
Nuclear magnetic resonance analysis was performed. The results are shown in Fig. 3.

The attribution and integrated intensities of the peaks in the spectrum of FIG. 3 are shown in Table 2 below.

Based on the above assignment and integrated intensity, FIG. 3 shows compound (Ia).
It is judged that this shows the NMR chart of.

Half-life The half-life of sample α was measured. The operation of pyrolysis is 1,4-
0.5 parts by weight of a sample was dissolved in 100 parts by weight of a mixed solvent of equal weight of dioxane and ethyl acetate, and the test was performed at a temperature of 85 ° C.

After the solution stabilizes at the prescribed temperature on the bath, first t = 0
Was sampled, and several times after each predetermined time from this point.

The initiator concentration in the sampled solution is actually the solution of the monomer (50% by weight of butyl acrylate in ethyl acetate).
It was measured by causing polymerization of (solution). During the polymerization, the solution was kept at the reflux temperature for a while to sufficiently remove oxygen.

Under the same conditions, in a very low initiator concentration range,
It was confirmed in advance that the square root of the initiator concentration and the polymerization rate (the time-differentiation of the conversion of a monomer into a polymer) have a virtually proportional relationship (linear relationship passing through the origin of coordinates). .

The results are shown in Fig. 4. The vertical axis of Fig. 4 is {-100ln
(1-conversion rate × 10 ⁻² )} ² , which is a value proportional to the square of the polymerization rate (the conversion rate of monomer to polymer finely divided by time), and the residual initiator The value is proportional to the concentration of.

 From FIG. 4, the half-life of sample α was determined to be 78 minutes.

Example of Polymerization Using Sample α as Polymerization Initiator Next, an example of obtaining a polymer composition by using the sample α described above as a polymerization initiator will be described.

Polymerization Example 1; A mixture of 94 parts by weight of butyl acrylate, 6 parts by weight of styrene, and 20 parts by weight of methanol was placed in a separable flask equipped with a stirring spring, heated to a reflux temperature (82 ° C), and then sample α0.005. Parts by weight were dissolved in 0.095 parts by weight of ethyl acetate and added.

Polymerization was continued for 120 minutes. On the way, the liquid temperature rose to 85 ° C and finally dropped to 83 ° C. Conversion of monomer is 21.2
It was part by weight.

To 120 parts by weight of the above solution, 0.4 parts by weight of diethyl tin diacetate was added, and a part of it was thinly applied to the release paper (about
After being developed (to a thickness of 1 mm), it was left for 7 hours in a blast dryer at 100 ° C. arranged in a room in a normal state (temperature 23 ° C., relative humidity 50%).

The obtained polymer (gel) was milky white and was a non-adhesive, slippery elastic body, and the gel fraction (dipping in ethyl acetate) was 85.4 parts by weight.

Polymerization Example 2; A mixture of 94 parts by weight of butyl acrylate, 4 parts by weight of acrylic acid, 1 part by weight of styrene and 20 parts by weight of ethanol was charged in a separable flask with a stirring spring, and the reflux temperature (85
After the temperature was raised to 0 ° C.), 0.005 parts by weight of sample α was dissolved in 0.095 parts by weight of ethyl acetate and added.

Polymerization was continued for 40 minutes. On the way, the liquid temperature increased to 88 ° C and finally decreased to 85 ° C again. Monomer conversion is
It was 24.7 parts by weight.

To 120 parts by weight of the resulting solution, 0.4 parts by weight of dibutyltin acetate was added, and a part of the solution was thinly (about
After unfolding (to a thickness of 1 mm), place it in a 100 ° C blast dryer placed in a room under normal conditions (temperature 23 ° C, relative humidity 50%).
Left for hours.

The obtained polymer (gel) was a transparent and sticky elastic body, and its gel fraction (dipping in ethyl acetate) was 98.0 parts by weight.

From the above Polymerization Examples 1 and 2, a vinyl polymer can be obtained by using the sample α as a polymerization initiator, and the obtained polymer constitutes a crosslinked product having a high gel fraction by the action of water such as air. I understand that

〔The invention's effect〕

As described above, according to the present invention, when polymerizing a vinyl-polymerizable monomer, it can be used as a polymerization initiator in the same manner as a conventional radical polymerization initiator, and the obtained polymer composition is in air. A novel alkoxysilyl group-containing azo compound which can give the ability to crosslink by the action of moisture such as the moisture of the above is obtained. Therefore, by using the alkoxysilyl group-containing azo compound of the present invention as a polymerization initiator, it is possible to easily obtain a polymer composition capable of forming a crosslinked product having a high gel fraction by the action of water in the air or the like. Becomes

Then, the polymer composition obtained as described above,
It can be used for various purposes such as a modified silicone type sealing agent, a cross-linking type adhesive or a reactive adhesive.

[Brief description of drawings]

FIG. 1 shows a product sample α obtained according to one embodiment of the present invention.
FIG. 2 is an infrared absorption spectrum of a product sample α obtained by one embodiment of the present invention, FIG. 3 is an H-nuclear magnetic resonance spectrum of sample α, and FIG. is a diagram showing the thermal decomposition process of the sample alpha, and the vertical axis value proportional to the residual concentration {-100ln (1- conversion × 10 ^{2)} 2,} the horizontal axis represents the heating time.

Claims (3)

[Claims] 1. A compound represented by the general formula (I): (In the formula (I), X is an alkoxy group having 1 to 4 carbon atoms, and may be the same or different, n is an integer of 2 or 3, R ¹ is H or An alkoxy silyl group-containing azo compound represented by the formula (1): an alkyl group having 1 to 4 carbon atoms, and R ² represents a dimethylene group or a trimethylene group. 2. General formula (II); (In the formula (II), X is an alkoxy group having 1 to 4 carbon atoms, and may be the same kind or different kinds,
n is 2 or 3, R ¹ is H or an alkyl group having 1 to 4 carbon atoms, and R ² is a dimethylene group or trimethylene group. An alkoxysilyl group-containing isocyanate represented by the formula: A method for producing an alkoxysilyl group-containing azo compound, characterized in that the compound represented by the general formula (I) according to claim 1 is obtained by mixing and reacting with a hydroxyl group-containing azo compound. 3. A radical polymerization initiator comprising the alkoxysilyl group-containing azo compound represented by the general formula (I) according to claim 1.