JPH11171999A - Production of silicate oligomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient method for stably producing an excellent silicate oligomer. SOLUTION: This method for producing a silicate oligomer by carrying out hydrolysis condensation of a tetraalkoxysilane comprises a step for keeping the tetraalkoxysilane at a temperature above the boiling point of the tetraalkoxysilane while blowing an inert gas at the space velocity of 1-30 for >=4 hr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to the production of silicate oligomers useful for various applications. More specifically, the present invention relates to a method for producing an oligomer which is a low condensate by hydrolytic condensation of tetraalkoxysilane.

[0002]

2. Description of the Related Art Tetraalkoxysilane represented by Si (OR) ₄ is a compound which has been known for a long time, and reacts with water to form an oligomer which is a low condensate by hydrolysis and a subsequent condensation reaction. It is known.
In recent years, oligomers of tetraalkoxysilane have attracted attention as being capable of being used alone or in combination with other organic compounds or inorganic compounds for various uses.

[0003]

However, the oligomer formation reaction of tetraalkoxysilane involves the formation of -OH by hydrolysis, followed by a dehydration reaction between -OH and a dealcoholation reaction with -OR. Entanglement and control thereof are difficult, and the resulting oligomer has poor storage stability depending on the reaction conditions, and may thicken during storage, or may thicken or gel when blended with other components. Further, depending on the reaction conditions, the monomer may remain and cannot be easily removed. In particular, when tetramethoxysilane is used as the tetraalkoxysilane, tetramethoxysilane, which is a monomer, has been reported to cause damage to the cornea, and has a problem in terms of environmental safety.

Further, in the production of these silicate oligomers, if the condensation reaction step is not sufficient, silanol groups will remain, resulting in an increase in viscosity and molecular weight during storage of the silicate oligomer, and in the worst case, gelation. It has been found out by the present inventors that this has occurred in some cases.
When a tetramethoxysilane monomer that may cause damage to the cornea is used as a raw material, it is desirable to reduce the residual amount of the monomer as described above. Therefore, the present inventors have previously described in Japanese Patent Application Laid-Open No. Hei 7-48454 a tetramethoxysilane oligomer having a small amount of monomer, Japanese Patent Application Laid-Open Nos. H8-3174, H8-3175, and H8-3176. Have proposed tetramethoxysilane oligomers having excellent characteristics with few specific metal impurities and OH groups.

However, the present inventors have further studied the industrial production of such silicate oligomers having a low silanol and low monomer content. -10
It has been found that it is difficult to efficiently reduce the amount of the residual monomer in the product even if it is held for a long time, and it is necessary to hold for a very long time. on the other hand,
If the liquid temperature is increased to shorten the monomer removal time, the product oligomer itself will volatilize,
There was a problem that the yield became poor. For example, in Japanese Patent Application Laid-Open No. H8-3174, methanol is removed by heating at 130 ° C. for 2 hours after heating under reflux, and then further heated to 150 ° C., and nitrogen is blown at SV50 to remove monomers. The complicated conditions are required. Under such heating conditions, in order to apply to industrial production, heating with medium pressure steam is required for removing the solvent and by-product methanol and for removing the monomer, which is costly and complicated. Further, it has been found that under such conditions, the oligomer as a product may be removed together with the monomer.

As described above, it has been difficult to industrially produce a silicate oligomer with a good yield by removing the monomer component in the silicate oligomer and reducing the silanol content, so that a silicate oligomer having high characteristics can be produced in a short time and with a good yield. A method capable of mass production was strongly desired.

[0007]

Means for Solving the Problems Accordingly, the inventors of the present invention have conducted further intensive studies. In the production of the silicate oligomer, the temperature was set to the boiling point of the tetraalkoxysilane monomer or higher, and an inert gas was blown at SV = 1 to 30. While maintaining for 3 hours or more, it was found that the amount of the tetraalkoxysilane monomer and silanol group could be rapidly reduced, and the present invention was reached. That is, the present invention includes a step of maintaining the liquid temperature at or above the boiling point of the tetraalkoxysilane monomer and maintaining the inert gas at SV = 1 to 30 for at least 4 hours while hydrolyzing and condensing the tetraalkoxysilane to obtain a silicate oligomer. And a method for producing a silicate oligomer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The present invention relates to the production of a silicate oligomer obtained by hydrolyzing and condensing a tetraalkoxysilane. In the present invention, the tetraalkoxysilane as a raw material refers to a compound having the following chemical formula.

[0009]

## STR1 ## Si (OR) ₄ wherein R is an alkyl group, preferably an alkyl group having 1 to 6 carbon atoms. Especially preferably, it is a C1-C4 alkyl group, More preferably, it is a methyl group. R may have different groups. These alkoxysilanes, especially alkoxysilanes in which R is a methyl group, are used for the properties of the silicate oligomer and the coating film obtained by applying the silicate oligomer by the hydrolysis condensation reaction as described later, for example, the hardness, scratch resistance, and coating resistance of the coating film. Excellent in solvent properties, stain resistance, etc. That is, in the case of tetramethoxysilane having a methyl group as R, the hydrolysis-condensation reaction proceeds most rapidly, and the obtained tetramethoxysilane oligomer is compared to other oligomers such as tetraethoxysilane and tetrabutoxysilane. High content in terms of silica, high effect of imparting stain resistance, weather resistance, abrasion resistance, etc. when added to various paints, and it is easy to obtain a glassy material by further hydrolysis. And so on.

[0010] These tetraalkoxysilanes are hydrolyzed and condensed to form oligomers. The hydrolysis and condensation reactions are carried out by adding water and, if necessary, a solvent and a catalyst to tetraalkoxysilane to cause a reaction.
The physical properties of the oligomer are generally the hydrolysis rate, that is, the amount of water reacted with tetraalkoxysilane is １ ／ mole times the alkoxy group of tetraalkoxysilane (the amount theoretically required for 100% hydrolysis and condensation). 10
Depends on the percentage, expressed as 0%. Therefore,
The amount of water may be appropriately selected according to the properties of the target oligomer, and the hydrolysis and condensation reaction may be performed. Usually, the amount of water is selected within a range of a hydrolysis rate of 25 to 70%, particularly preferably 35 to 60%. If the hydrolysis rate is less than 25%, the yield is not sufficient, and the content in terms of silica is not sufficient. On the other hand, if the hydrolysis rate exceeds 70%, the obtained silicate oligomer is very likely to gel and handling becomes difficult.

The method of adding water is not particularly limited. However, since heat is generated by the hydrolysis reaction of the tetraalkoxysilane, it is preferable to gradually add the water while stirring and cooling the inside of the system. The temperature at which water is added at this time is preferably equal to or lower than the boiling point of the alcohol generated by the condensation reaction, particularly preferably equal to or lower than 50 ° C, and more preferably equal to or lower than 45 ° C. When the temperature exceeds 50 ° C., the obtained silicate oligomer tends to be cloudy. It is presumed that this is because a high temperature causes a local condensation reaction to occur and an extremely high molecular weight condensate is produced.

The hydrolysis-condensation reaction can be carried out in the presence of a solvent. As the solvent, an alcohol having C1 to C5 is preferable, and an alcohol having the same carbon number as the alkoxy group of the tetraalkoxysilane as the raw material is more preferably used. For example, as the alcohol to be used, methanol is used when the alkoxy group of the alkoxysilane is a methoxy group, ethanol when the alkoxy group is an ethoxy group, propanol when the alkoxy group is a propoxy group, and butanol when the alkoxy group is a butoxy group. It is preferable to use the same alcohol as the alcohol. The amount of solvent added
It is sufficient if the amount of tetraalkoxysilane and water to be added is at least the amount required for uniform dissolution. Usually, the solvent is used in an amount of 0.1 to 10.0 times, preferably 0.5 to 5.0 times the mole of tetraalkoxysilane.

In the hydrolysis and condensation, a catalyst may be used. For example, organic acids such as oxalic acid, maleic acid, formic acid, and acetic acid; inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid; or various organometallic compounds such as boron compounds, titanium compounds, aluminum compounds, and tin compounds; or metal complexes. It is possible to use a known hydrolysis-condensation catalyst as appropriate. In addition, the hydrolysis condensation reaction, after adding water as described above, may be left to ripen at room temperature for a certain period of time or more, or may be heated for the purpose of allowing the reaction to proceed in a short time, such as alcohol or The reaction may be carried out under reflux conditions around the boiling point of the solvent used in the reaction.

When performing total reflux near the boiling point of the produced alcohol, a reaction time of about 2 to 5 hours is sufficient. The condensation reaction in the present invention is a reaction shown below. {SiOH +} SiOR → {Si-O-Si}
+ ROH ≡SiOH + ≡SiOH → ≡Si-O-Si≡
+ H ₂ O In this condensation reaction, silanol groups generated by hydrolysis of tetraalkoxysilane are reduced by a dealcoholization or dehydration condensation reaction to form siloxane bonds, and by-product alcohol and the like are extracted out of the system. Progresses more easily. Therefore, the temperature may be gradually raised from a temperature near the boiling point of the by-product alcohol. Then, the temperature is raised to a temperature equal to or higher than the boiling point of the tetraalkoxysilane monomer, and the temperature is maintained as described below. The present inventors have found that unless the temperature is raised to a temperature equal to or higher than the boiling point of the monomer, it is difficult to reduce the monomer concentration, and it is also difficult to quickly reduce the remaining amount of silanol groups. The silicate oligomer can be made stable by the rapid reduction of the amount of silanol according to the present invention. Further, when tetramethoxysilane is used as a raw material, unreacted tetramethoxysilane monomer which may damage the cornea remains The volume is reduced and safety is improved.

According to the present invention, the unreacted monomer component can be reduced by setting the temperature to a temperature higher than the boiling point of the monomer, and the condensation reaction can proceed efficiently, so that the silanol group content can be rapidly reduced. At this time, it is necessary to blow a specific amount of inert gas into the liquid. In the present reaction, it is very difficult to remove the monomer simply by raising the liquid temperature to the boiling point of the monomer without performing the operation of blowing the inert gas, and the condensation reaction is allowed to proceed promptly and the silanol group content is sufficiently increased. It has been clarified from the study by the present inventors that it is difficult to reduce the temperature. The reason for this is not fully understood, but is probably due to interactions between monomers and oligomers and other unexplained reasons.

When oligomerization is carried out using a plurality of types of tetraalkoxysilanes as raw materials, "above the boiling point of the monomer" means above the boiling point of all the tetraalkoxysilane monomers. By blowing a specific amount of inert gas at a temperature equal to or higher than the boiling point of the monomer according to the present invention, components such as by-product alcohol and solvent are efficiently extracted to the outside of the system, and the reaction proceeds more efficiently. It is thought that. The inert gas blown at this time is nitrogen,
Examples include helium and argon, but are not particularly limited thereto. As described above, in the present invention, the liquid temperature is set to be equal to or higher than the boiling point of the tetraalkoxysilane monomer, and while the inert gas is blown at SV = 1 to 30,
It is characterized by including a step of holding for 4 hours or more. As is clear from the above description, this inert gas blowing step gradually raises the liquid temperature following the hydrolysis of tetraalkoxysilane as described above. It is preferable to carry out the reaction after the temperature is raised to the boiling point of the tetraalkoxysilane monomer or higher.

It is necessary that the amount of blown gas be SV = 1 to 30, and that the total amount be kept at least 4 hours. If the time is less than 4 hours, the effects of reducing the monomer and reducing the silanol content are not sufficient. SV here is Space Velocity
However, in the present invention, the total charged liquid volume (m ³ ) is calculated as the specific gravity 1 from the total charged liquid weight of the raw material, and the number of Nm ³ of gas per unit time is calculated with respect to the charged liquid unit volume (1 m ³ ). It shall be expressed by whether it is blown or not. Therefore, the unit of SV is Hr ^-1 . In the present invention, usually, the reaction is promoted while distilling off the alcohol component by-produced in the reaction process,
The liquid temperature is gradually raised to reach a temperature higher than the boiling point of the monomer. In the case of employing such a process, it is preferable that the inert gas is blown after the distillation of the by-product alcohol is stopped to some extent. Preferably, the injection of the inert gas is started when the liquid temperature becomes equal to or higher than the boiling point of the produced alcohol or the boiling point of the solvent used, more preferably equal to or higher than the boiling point of the tetraalkoxysilane monomer. If the gas is blown before that, there is a possibility that a large amount of alcohol component that cannot be coagulated by the condenser may come out, which is not preferable.

If the SV is larger than 30, the silicate oligomer entrained by the blown gas goes out of the system, causing contamination in the pipes and adhesion to the condenser, etc., resulting in a serious problem of lowering the yield. Difficult to produce. Further, equipment for flowing a large amount of gas is required, and it is necessary to increase the size of auxiliary equipment such as a tank or a pump. Since the capacity of the condenser and the associated heat exchanger and the like need to be increased due to the increase in the amount of gas, it is very disadvantageous economically.

Conversely, if the SV is less than 1, it is difficult to efficiently advance the condensation reaction, and the cutting of the monomer component is very poor. Desirably, the range is 2 ≦ SV ≦ 30, and more preferably, the range is 3 ≦ SV ≦ 25. A total of 4 hours or more is required to maintain the liquid temperature at or above the boiling point of the tetraalkoxysilane monomer while blowing the inert gas. If it is shorter than this, the molecular weight of the obtained silicate oligomer will not be stabilized, and the physical properties may change during storage of the liquid. In particular, it is presumed that the remaining silanol groups cannot be ignored and cause a problem in storage stability. Also, the effect of removing monomers is not sufficient. Preferably 4-20 hours,
More preferably, the holding time is 5 to 15 hours.

In this way, the silicate oligomer as a product is obtained by performing the inert gas blowing operation of the present invention. Preferably, the residual amount of the tetraalkoxysilane monomer in the system is 1 wt% or less, more preferably 0.5 watt.
Continue until t% or less. As described above, in particular, the residual monomer of tetramethoxysilane is not preferable in terms of environmental safety, but if it is reduced to the above range, volatilization to the atmosphere can be substantially ignored, and if the silanol group remains, the liquid of the silicate oligomer can be reduced. This is because the storage stability is poor and the viscosity increases and the molecular weight increases during storage, but if the inert gas is blown according to the present invention until the residual amount of the monomer falls within the above range, the silanol group is sufficiently reduced.

The silicate oligomer thus obtained has excellent storage stability in a liquid state by itself, and also exhibits excellent properties when blended with various components such as an organic resin. The silicate oligomer can be used as it is for paint additives, binders and other various applications, or can be suitably used as a hydrolyzing solution for film-forming compositions, binders and other various applications.

When tetramethoxysilane is used as the tetraalkoxysilane and the alkoxy groups of the silicate oligomer are all methoxy groups, depending on the purpose such as blending in various paints, the resin in the blended paint may be used. In some cases, storage stability may be reduced due to compatibility with or reactivity with components, and behavior in a paint or coating film may need to be improved. Such a case can be dealt with by introducing an organic group other than a methoxy group, particularly an alkoxy group, into the silicate oligomer. For this purpose, it is convenient to carry out the introduction by transesterifying a compound represented by R'OH having a desired introduction group R'O- with an alkoxy group such as a methoxy group of the silicate oligomer. . The timing of introduction can be appropriately selected in view of the convenience of the process and the like, and may be introduced before the gas blowing step at the boiling point or higher of the tetraalkoxysilane monomer according to the present invention, or after the gas blowing step. No problem. Example 1 [Synthesis of silicate oligomer 1] In a 4.5-liter separable flask equipped with a jacket, 2699.05 g of tetramethoxysilane (manufactured by Mitsubishi Chemical Corporation) was charged, and then 851.2 g of methanol was charged. Here, 0.
A mixture of 35.4 g of 1N hydrochloric acid and 322.0 g of degassed and demineralized water was gradually added dropwise with stirring. At this time,
Although the liquid temperature rises due to the heat generated by the hydrolysis, the liquid temperature was controlled within the range of 25 ± 3 ° C. When the addition of the aqueous hydrochloric acid was completed, the jacket was heated, and the reflux started when the internal temperature was reduced to about 65 ° C. In this state, total reflux was continued for 4 hours.

Once the circulation of the jacket oil was stopped and left as it was, and the liquid temperature was cooled to 60 ° C. or lower, 692.11 g of butanol was charged. Thereafter, the temperature was raised again, and the mixture was completely refluxed at an internal temperature of 65 ° C. for 1 hour. Then, the methanol produced as a by-product was distilled off, and the temperature of the liquid was gradually raised to 150 ° C. while distilling off the methanol. Continued. When the liquid temperature reached 150 ° C., nitrogen gas was blown at SV = 10. 8 hours 15 after starting to blow
After maintaining at 0 ° C., the mixture was naturally cooled to obtain 2043 g of silicate oligomer 1. Example 2 [Synthesis of Silicate Oligomer 2] 201.8 g of tetramethoxysilane (manufactured by Mitsubishi Chemical Corporation) and 63.7 g of methanol were charged into a 0.5 liter glass corbene, and degassed with 0.1N hydrochloric acid. 27.5 g of a mixed solution with salt water
Was slowly added dropwise with stirring. When stirring was continued for 10 minutes, the internal temperature was stabilized at 34 ° C. When the internal temperature reached about 65 ° C. after the start of the temperature rise, total reflux was applied and maintained for 5 hours.

Thereafter, the internal temperature was gradually raised to 150 ° C. while slowly removing by-produced methanol. When the internal temperature reaches 150 ° C, the nitrogen gas is
Blowing started at 7.5. After maintaining at 150 ° C. for 7 hours while blowing nitrogen gas, the mixture was naturally cooled to obtain 2102 g of a silicate oligomer. Example 3 [Synthesis of silicate oligomer 3] In a 4.5-liter separable flask with a jacket, methanol 716 was added.
g is charged first, then tetramethoxysilane 2
270 g (manufactured by Mitsubishi Chemical Corporation) was charged with 716 g of methanol. A mixture of 2.66 g of 4.1 wt% aqueous hydrochloric acid and 269.0 g of degassed and demineralized water was charged with stirring for about 1 hour. Start heating and reduce internal temperature to approx.
When the temperature reached ℃, the whole reflux was applied, and this was maintained for 2 hours.

Thereafter, methanol as a by-product was distilled off over about 6 hours, and then the internal temperature was gradually raised to 150 ° C. From the time when the internal temperature reached 150 ° C., the blowing of nitrogen gas was started at SV = 9.2. After holding at 150 ° C. for 7 hours while blowing nitrogen gas, the mixture was naturally cooled to obtain silicate oligomer 3. Example 4 [Synthesis of silicate oligomer 4] Tetramethoxysilane (manufactured by Mitsubishi Chemical Co., Ltd.) (228.9 g) was charged into a 500 ml glass corbene, and then methanol (72.2 g) was charged. A mixture of 3.0 g of 0.1N hydrochloric acid and 17.7 g of degassed and demineralized water was gradually added dropwise with stirring. At this time, the liquid temperature rises due to heat generated by hydrolysis, but the liquid temperature was controlled within the range of 25 ± 3 ° C. When the addition of the hydrochloric acid solution was completed, the kolben was heated in an oil bath, and reflux started when the internal temperature was set to about 65 ° C. In this state, total reflux was continued for 4 hours. Thereafter, distillation of the produced methanol was started, and the distillation of methanol was continued while gradually increasing the temperature of the liquid to 125 ° C.

From the time when the internal temperature reached 125 ° C., nitrogen gas was blown in at SV = 15. After maintaining the temperature at 125 ° C. for 5 hours after the start of blowing, the mixture was naturally cooled to obtain 168.0 g of silicate oligomer 4. Comparative Example 1 [Synthesis of silicate oligomer 5] The final temperature of the solution was 15
The same operation as in Example 4 was carried out except that the temperature was 0 ° C., the temperature was maintained for 5 hours, and the blowing of nitrogen gas was not carried out, whereby 171.2 g of silicate oligomer 5 was obtained. Comparative Example 2 [Synthesis of silicate oligomer 6] The final temperature of the solution was 10
The same operation as in Example 4 was carried out except that the temperature was 0 ° C., the temperature was maintained at this temperature for 5 hours, and the blowing of nitrogen gas was not carried out, whereby 176.1 g of silicate oligomer 6 was obtained. Comparative Example 3 [silicate oligomers 7 (a), 7 (b), 7 (c)
Synthesis of 7 (d)] 533.91 g of tetramethoxysilane (manufactured by Mitsubishi Chemical Corporation) was charged into a 1-liter glass corvene, and then 168.27 g of methanol was charged. To this, 7.0 g of 0.1N hydrochloric acid water and 6 g of degassed
The mixture of 2.5 g was gradually added dropwise with stirring. At this time, the liquid temperature rises due to heat generated by hydrolysis, but the liquid temperature was controlled within the range of 25 ± 3 ° C. After the addition of hydrochloric acid water, heat the Kolben in an oil bath,
Reflux started at an internal temperature of about 65 ° C. After continuing total reflux for 4 hours in this state, distillation of produced methanol was started, and while gradually increasing the temperature of the liquid to 125 ° C, distillation of methanol was continued, and the liquid temperature was raised to 125 ° C. From that point, nitrogen gas blowing was started at SV = 15.

Samples were sampled at 0, 1, 3, and 5 hours after the temperature reached 125 ° C. and the blowing of nitrogen gas was started, and then the sample was naturally cooled. Samples of the final products at 0 hour, 1 hour, 3 hours, 5 hours, and after cooling were respectively silicate oligomer 7 (a), silicate oligomer 7 (b), silicate oligomer 7 (c),
These are referred to as silicate oligomer 7 (d) and silicate oligomer (e). Example 5 [Gas Chromatographic Analysis] Gas chromatographic analysis was carried out to examine the residual amount of the silicate oligomers 1 to 6. [Measurement conditions] Apparatus: Shimadzu GC-14A Column used: J & W glass capillary column DB5 (0.53 mm × 30 m) Temperature: Column (initial): 40 ° C. Column (heating rate): 10 ° C./min Column (final temperature) ): 250 ° C. Inlet: 270 ° C. Detector (TCD): 270 ° C. Detector soda: 270 ° C. TCD current: 75 mA Carrier gas: sample side 8 ml / min Control side 60 ml / min Internal standard: meta-xylene In Example 1. The concentration of the tetramethoxysilane monomer in the obtained silicate oligomer 1 was not more than the lower detection limit (0.2
Wt% or less), which was far below the upper limit at which volatilization into the atmosphere was problematic.

The concentration of the tetramethoxysilane monomer in the silicate oligomer 2 obtained in Example 2 is below the lower limit of detection (less than 0.2% by weight), which is far below the upper limit at which volatilization into the atmosphere is a problem. I was The concentration of the tetramethoxysilane monomer in the silicate oligomer 3 obtained in Example 3 was not more than the lower detection limit (not more than 0.2% by weight).
And it was far below the upper limit where volatilization into the atmosphere was a problem.

The concentration of the tetramethoxysilane monomer in the silicate oligomer 4 obtained in Example 4 is below the lower limit of detection (less than 0.2% by weight), which is far below the upper limit at which volatilization into the atmosphere is a problem. I was The concentration of the tetramethoxysilane monomer in the silicate oligomer 5 obtained in Comparative Example 1 was 1.77 wt%, which was a concentration that could not be ignored in the atmosphere and was not desirable as a product. If the inert gas is not injected, the tetramethoxysilane monomer in the silicate oligomer is not sufficiently reduced even if the liquid temperature is maintained for a long time at or above the boiling point of the tetramethoxysilane monomer. Exposure to vapor is a concern.

The concentration of the tetramethoxysilane monomer in the silicate oligomer 6 obtained in Comparative Example 2 was 1.67.
wt%, which is a concentration that cannot be ignored in volatilization into the atmosphere, and was not desirable as a product. If the inert gas is not blown, the amount of tetramethoxysilane monomer in the silicate oligomer is not sufficiently reduced, so that volatilization into the atmosphere becomes a problem, and there is concern about exposure to steam. Example 6 In order to confirm the storage stability of a silicate oligomer, a viscosity measurement and a molecular weight measurement were performed under the following conditions. [Viscosity measurement conditions] Apparatus: E-type viscometer manufactured by Tokyo Keiki Co., Ltd. Measurement temperature: 25 ° C Sample: 1.2 ml [GPC analysis conditions used for molecular weight measurement] Apparatus: Waters high temperature GPC 150C column : 2 pieces of PLgel 500μ (5μ) + 1 piece of 100Å (5μ) Temperature: Column 40 ° C, Injection port 30 ° C, Pump 30 ° C Solvent: Ethyl acetate 1.0ml / min Detector: RI detector -32 × 1 RIU / FS sample: diluted to 5% by weight with ethyl acetate and injected with 100 μl Chart speed: 5 mm / min Data processing: CP-8000 manufactured by Tosoh The viscosity of silicate oligomer 1 obtained in Example 1 is 3
It was 3.9 cp and the weight average molecular weight Mw was 1,635.

Further, the silicate oligomer 1 was put in a closed glass bottle, and the viscosity and the weight average molecular weight after one month and three months at 50 ° C. were confirmed. As a result, 34.1 cp, Mw
= 1645, 34.3 cp, Mw = 1650, there was almost no change, and the storage stability was very good. The viscosity of the silicate oligomer 2 obtained in Example 2 is 28
The weight average molecular weight Mw was 2377.

Further, the silicate oligomer 2 was put in a closed glass bottle, and the viscosity and the molecular weight after one month and three months at 50 ° C. were confirmed. As a result, 284 cp, Mw = 238
5, 285 cp, Mw = 2388, almost no change, and the storage stability was very good. The viscosity of the silicate oligomer 3 obtained in Example 3 was 33.9 cp,
The weight average molecular weight Mw was 1198.

Further, the silicate oligomer 3 was placed in a closed glass bottle, and the viscosity and the molecular weight after 1 month and 3 months at 50 ° C. were confirmed. As a result, 33.8 cp, Mw = 120
0, 34.0 cp, Mw = 1198, there was almost no change, and the storage stability was very good. The viscosity of the silicate oligomer 4 obtained in Example 4 was 5.6 cp, and the weight average molecular weight Mw was 557.

Further, the silicate oligomer 4 was put in a closed glass bottle, and the molecular weights after one month and three months at 50 ° C. were confirmed. As a result, there was almost no change to 559 and 560, respectively, and the storage stability was very good. Comparative Example 1
Weight average molecular weight M of the silicate oligomer 5 obtained by
w was 539.

The silicate oligomer 5 was placed in a closed glass bottle, and the molecular weight was confirmed after 1 month and 3 months at 50 ° C. As a result, changes with time were confirmed as 542 and 552, and storage stability was not sufficient. The weight average molecular weight Mw of the silicate oligomer 6 obtained in Comparative Example 2 was 522.

The silicate oligomer 6 was placed in a closed glass bottle, and the molecular weight was confirmed after 1 month and 3 months at 50 ° C.
As a result, changes over time were confirmed as 538 and 558, and the storage stability was not sufficient. Silicate oligomers 7 (a), 7 (b), 7 (c), 7 (d) obtained in Comparative Example 3
And 7 (e) have a viscosity of 22.2 cp, 42.2 c
p, 60.0 cp, 77.4 cp and 79.5 cp. In addition, these silicate oligomers 7 (a), 7
The weight average molecular weights of (b), 7 (c), 7 (d) and 7 (e) are 860, 1129, 1439, 1702 and 1
725. As described above, when the inert gas blowing time is less than 3 hours, the physical properties of the silicate oligomer are not stable, and it is understood that the silicate oligomer is not desirable as a product.

[0037]

According to the production method of the present invention, a silicate oligomer having a low silanol, a low residual amount of monomer and excellent in safety and storage stability can be obtained in a short time by efficient operation.

Claims (1)

[Claims] 1. A method for producing a silicate oligomer by hydrolytic condensation of tetraalkoxysilane, comprising the step of keeping the liquid temperature at or above the boiling point of the tetraalkoxysilane monomer and maintaining the inert gas at SV = 1 to 30 for at least 4 hours. A method for producing a silicate oligomer.