JP3449456B2 - Organopolysiloxane resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an organopolysiloxane resin composition containing a silanol group (≡Si—OH) useful as a coating agent, and particularly to an organic solvent capable of stabilizing the silanol group. The present invention relates to an organopolysiloxane resin composition.

[0002]

2. Description of the Related Art When an organopolysiloxane resin is used, for example, in a heat-curable coating material vehicle having excellent heat resistance and weather resistance, it generally has a hydrolyzable substituent (such as a silanol group). It is synthesized by hydrolyzing a silane monomer having 4 to 4 and optionally further condensing it, but since the silanol group is unstable,
Poor storability due to easy condensation over time. Therefore, in the organopolysiloxane resin composition supplied as a commercial product, the silanol group content is 1 to 5% by weight, or 4 to 20% by mole (in order to minimize the change with time of these resins. It is controlled within (to the silicon atom).

On the other hand, some siloxane resins containing silanol groups are used as a coating agent for improving the hardness and scratch resistance of plastic moldings such as acrylic resins and polycarbonate resins. There is one that forms a film called a hard coat of hardness. This is an alkoxysilane R ¹ _n Si (OR ² ) _r (r is required to be 3 and / or 4 and contains ¹ or ² ) of _r ¹ alkoxy groups directly bonded to a silicon atom which is a hydrolyzable substituent. Those may be used in combination, and are on average greater than 2 and 4 or less, and n + r is 4.)
On the other hand, it is a resin obtained by hydrolyzing the alkoxysilane under mild conditions using r molar equivalent or more of water.

In this case, since the silanol groups are abundantly contained by the hydrolysis, a resin composition obtained by mixing the obtained silanol group-containing siloxane with inorganic oxide particles typified by colloidal silica is obtained. The silanol groups contained in the surface of the SiO ₂ fine particles and the siloxane resin in the silica sol are dehydrated and condensed by heat treatment in the presence of a catalyst, and a stable siloxane bond (--Si
-O-Si-) is formed. Therefore, the greater the content of silanol groups in the siloxane resin, the greater the crosslink density in the cured product, resulting in higher hardness.

However, the silanol group is essentially unstable, and the condensation proceeds gradually even at room temperature, so that the silanol group in the resin composition before use is reduced. Therefore, when used as a hard coat, The hardness and scratch resistance of the obtained coating are reduced. As described above, the silanol group-containing siloxane resin has excellent performances, but has a big drawback that it is poor in storage stability.

It is known that the silanol group is most stable in the pH range of 3-5. Therefore, by adjusting the pH to 3 to 5, the condensation of silanol groups can be considerably suppressed, and by doing so, the storage stability can be improved. However, there is a drawback that the storage stability is not sufficient because the temperature rises during transportation.

On the other hand, the organopolysiloxane resin coating agent is generally (1) a hydrolysis / partial condensate of an alkoxysilane, (2) an organic solvent and / or water, (3) a curing catalyst, and (4) if necessary. It is composed of metal oxide fine particles to be used. As the above organic solvent,
Toluene (relative permittivity 2.38, 25 ° C) that easily dissolves organopolysiloxane resin, xylene (relative permittivity 2.40 (average value of ortho, meta, para form), 20 ° C)
Aromatic solvents such as methanol, methanol (relative permittivity 32.
6, 25 ℃), ethanol (relative permittivity 24.3, 25
Lower alcohols such as (° C.) Are used.

However, since the silanol groups contained in the organopolysiloxane resin in these coating agents are extremely unstable, a great improvement is required. In particular, a system containing water has a problem that not only the storage stability but also the adhesion to a plastic substrate and the film forming property are poor. In order to solve these problems, a method has been proposed in which an excessive amount of water is azeotropically distilled off with an alcohol as a solvent to suppress the water content to 15% by weight or less (Japanese Patent Publication No. 5-428). However, although the storage stability and workability of the coating agent are improved by the method, the storage stability is still insufficient and it is necessary to distill off water under reduced pressure, which complicates the manufacturing process. There was also a drawback that

[0009]

The inventors of the present invention have made extensive studies to solve the above-mentioned drawbacks, and as a result, the condensation reaction of the silanol group was found to be nucleophilic to the silicon atom by the oxygen atom in the silanol group. By undergoing attack, the transition state of the reaction becomes more stable in a highly polar solvent, and thus by using a polar solvent with a relatively low polarization having a range of relative permittivity, The inventors have found that the stability can be improved by keeping the activation energy large and delaying the condensation of the silanol groups, and arrived at the present invention. Therefore, an object of the present invention is to provide a silanol group-containing organopolysiloxane resin composition which has excellent storage stability and is resistant to deterioration over time because it does not condense at room temperature.

[0010]

The above object of the present invention is to:
a) Average composition formula R ¹ _n Si (OR ² ) _p (OH) _q O
100 parts by weight of a siloxane resin represented by _{(4-n-p-q) / 2} (hereinafter abbreviated as Formula 1), and b) tert-
Butanol, tert-amyl alcohol, methyl iso
At least one selected from butyl ketone (MIBK)
Organopolysiloxane resin composition containing 40 to 2,000 parts by weight of a seed organic solvent. However, in the above average composition formula, R1 is a hydrogen atom or an organic group having 1 to 18 carbon atoms, R2 is an alkyl group having 1 to 6 carbon atoms, and n, p and q are each 0≤n≤. 1.8, 0
≦ p ≦ 1, 0.2 ≦ q ≦ 3, and 0.8 ≦ n + p + q
It is a number that satisfies <4.

The organopolysiloxane resin represented by the above formula 1, which is an essential component in the composition of the present invention, has R ¹ _n
At least 1 represented by Si (OR ² ) _r (hereinafter abbreviated as Equation 2)
It is preferably a siloxane resin composed of a hydrolyzed condensate of one kind of alkoxysilane. The alkoxy R ¹ of the silane is the same as R ¹ in the formula 1, is a hydrogen atom or an organic group having 1 to 18 carbon atoms, specifically, methyl group,
In the skeleton of alkyl groups such as ethyl group, propyl group, butyl group, hexyl group, decyl group, alkenyl groups such as vinyl group and allyl group, cycloalkyl groups such as cyclohexyl group, aryl groups such as phenyl group, and alkyl With a group such as ether, ester, carbonyl, etc., a halogen atom as a substituent, an epoxy group, an amino group, an acryloxy group, a methacryloxy group, a carboxyl group, a mercapto group, and an organic group containing a group such as a hydroxyl group. To be

In the present invention, among these groups, methyl group, phenyl group, γ-glycidoxypropyl group, γ
A-(meth) acryloxypropyl group is preferable, and a methyl group is particularly preferable. R ^{2 is} also the same as R ^{2 in} Formula 1, and is an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, an isopropyl group, a butyl group, a methyl group,
The ethyl group is preferred. n is 0 or 1, r is 3 or 4, and n + r = 4. If necessary, monoalkoxysilane and dialkoxysilane with r = 1 or 2 may be used in combination within a range in which the average of r is larger than 2.

Specific examples of the alkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltriisopropenoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane and ethyltriisopropoxysilane; n
-Propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltriisopropoxysilane,
n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane;

Phenyltrimethoxysilane, phenyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, trimethoxyhydrosilane, triethoxyhydrosilane; γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltri Ethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4
-Epoxycyclohexyl) ethyltriethoxysilane, γ (meth) acryloxypropyltrimethoxysilane, γ (meth) acryloxypropyltriethoxysilane;

Γ-aminopropyltrimethoxysilane,
γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, etc. Can be mentioned. These alkoxysilanes may be used alone or in combination of two or more.

Specific examples of the monoalkoxysilane and dialkoxysilane in which r is 1 or 2 include dimethoxydiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenylmethyldimethoxysilane, Phenylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethylgetoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ -Aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane and the like can be mentioned.

The hydrolysis of the alkoxysilane to obtain the polysiloxane resin used in the present invention is preferably carried out under the mixing of water containing an acidic hydrolyzable catalyst.
The hydrolysis catalyst has a pH of 2 to 5 in contact with water.
It can be used by appropriately selecting from known catalysts exhibiting acidity. In the present invention, it is particularly preferable to use a solid acid such as an acidic hydrogen halide, a carboxylic acid, a sulfonic acid, an acidic or weakly acidic inorganic salt, or an ion exchange resin.

Specific examples thereof include hydrogen fluoride, hydrochloric acid,
Organic acids represented by nitric acid, sulfuric acid, acetic acid, and maleic acid; methylsulfonic acid, cation exchange resins having a sulfonic acid group or a carboxylic acid group on the surface, and the like. Also,
The amount of the hydrolysis catalyst may be appropriately adjusted according to various uses, but in the present invention, it is preferably in the range of 0.001 to 5 mol% with respect to the alkoxysilane.

The amount of water in the hydrolysis reaction in the present invention is 0.5r molar equivalent to 1.5 with respect to the number r of alkoxy groups present in one molecule of the raw material alkoxysilane.
It is preferably within the range of r molar equivalents. If the amount is 0.5 rmol equivalent or less, hydrolysis does not proceed completely and the alkoxy group may remain excessively. If it is 1.5 rmol equivalent or more, excess water that is not involved in hydrolysis remains in the system,
Since the water content in the siloxane composition is high, the storage stability and the film forming property may decrease.

The silanol group content in the hydrolyzed condensate of the alkoxysilane represented by the above formula 2 thus obtained must be within the range of 0.2 to 3, which is an appropriate range of q. . If q is less than 0.2, the crosslink density at the time of curing will decrease, and the hardness of the coating will be insufficient. Further, when q is larger than 3, a large amount of monomers and dimers of the alkoxysilane hydrolyzate will be present, so that the cured product will have high hardness, but the appearance will be poor such as easy cracking. Become. Further, the amount p of residual alkoxy groups after the hydrolysis-condensation reaction needs to be in the range of 0 to 1. When p is more than 1, the crosslink density at the time of curing is lowered and the hardness becomes insufficient, and in addition, the adhesion to the substrate is lowered.

The organic solvent, which is an essential component in the composition of the present invention, is added not only as a diluent for adjusting the solid content of the liquid but also for reducing the condensation reactivity of silanol. Is. Therefore, 10-35
It is necessary that the solvent has a relative dielectric constant of 4 to 16 in the temperature range of ° C.

In a polar solvent having a relative dielectric constant of more than 16 in the temperature range of 10 to 35 ° C., the activation energy is lowered and the condensation is accelerated. Further, it is known that the silanol group usually has a polarized structure represented by the following chemical formula 1. Therefore, in a non-polar solvent having a relative dielectric constant of less than 4, such as toluene or xylene, the solubility of the resin having a silanol group with large polarization is extremely low, and even if dissolved, the silanol group alone is electrically unstable. Therefore, it is considered that condensation is promoted by approaching each other.

[Chemical 1]

[0023]

In the present invention, in particular , methyl isobutyl ketone (relative permittivity 13.1, 20 ° C.) , tert-butanol (relative permittivity 10.9, 30 ° C.), and tert.
- either in amyl alcohol (dielectric constant 5.8,25 ℃)
At least one solvent selected from is used.

In the present invention, tert- butanol and / or tert-amyl alcohol, which is an organic group having a bulky polarized substituent, is particularly preferable. That is, the electrically polarized silanol group is in an equilibrium state in which binding and dissociation are repeated with many surrounding solvents. Therefore, tert-butanol and tert having bulky substituents
-When amyl alcohol forms a hydrogen bond with a silanol group, it becomes difficult for other silanol groups to approach due to the steric effect of the tert-butyl group or the tert-amyl group. The condensation reaction is particularly hindered because it is difficult to take the position state.

The amount of organic solvent used is siloxane resin 10
It is preferably in the range of 40 to 2,000 parts by weight with respect to 0 parts by weight. If it is less than 40 parts by weight, the resin concentration is too high and the viscosity becomes high, resulting in poor workability, and the silanol group becomes unstable, and condensation proceeds, which is not suitable.
If it exceeds 2,000 parts by weight, the solid content of the coating liquid is too low to obtain a cured film having a sufficient film thickness, resulting in deterioration of performance.

In the present invention, an organic solvent other than the above may be used together within a range that does not affect the stability of the silanol group. For example, to provide a combination of acid / basic compounds that act as buffers for adjusting pH (acetic acid and sodium acetate, disodium hydrogen phosphate and citric acid, etc.), dispersion solvents, or to provide excellent film performance. , An organic resin, a pigment, a dye, a leveling agent, an ultraviolet absorber, a storage stabilizer and the like can be appropriately added and used.

The dispersion solvent may be used within a range that does not impair the effects of the present invention. Examples of the dispersion solvent include water, or lower alcohols such as methanol, ethanol, isopropyl alcohol, n-butanol, isobutanol, and ketones such as methyl ethyl ketone (MEK) from the viewpoint of stability and availability of the sol. It is preferable to use. In addition, in the present invention, in order to exhibit the above-mentioned solvent effect, it is preferable that the water content in the composition is 15% by weight or less. When the water content is 15% by weight or more, water is selectively coordinated with the silanol group, so that hydrogen bond between the solvent and the silanol group is not generated, and the silanol group stabilizing effect is reduced.

Solvents other than the organic solvent which are preferably used in the composition of the present invention may be added to the outside of the system by means such as distillation under reduced pressure, if necessary, from the viewpoint of improving the stability after preparing the target liquid. Is preferably removed. For example, it is preferable to distill off a lower alcohol such as an alcohol produced by hydrolysis of an alkoxysilane as a raw material under reduced pressure as much as possible. In this case, it is preferable that a solvent that contributes to the stabilization of silanol is added in advance to form a dilute solution, and the solution temperature is set to a maximum of 40 ° C., and if possible, vacuum distillation is performed at 30 ° C. or less.

In the composition of the present invention, the two major components, the alkoxysilane and the specific organic solvent, are essential components. Depending on the intended use of the coating agent, the hardness and abrasion resistance of the cured film A known curing catalyst, metal oxide fine particles, and other additives may be appropriately contained in order to improve the above properties or impart optical functionality such as increasing the refractive index.

Specific examples of the curing catalyst include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium methylate, sodium acetate, potassium acetate, sodium formate, potassium formate, n-hexylamine, potassium propionate, tributylamine. , Basic compounds such as diazabicycloundecene, tetraisopropyl titanate, tetrabutyl titanate, aluminum triisobutoxide, aluminum triisopropoxide, γ-
Aminopropyltrimethoxysilane;

Metal-containing compounds such as aluminum acetylacetonate, aluminum perchlorate, aluminum chloride, cobalt octylate, cobalt acetylacetonate, iron acetylacetonate, tin acetylacetonate, dibutoxytin octylate, p-toluene. Examples thereof include acidic compounds such as sulfonic acid and toluchloroacetic acid. The addition amount of the curing catalyst is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the organopolysiloxane resin.

Specific examples of the metal oxide fine particles include silica, alumina, titanium oxide (TiO ₂ ), cerium oxide (CeO ₂ ), tin oxide (SnO ₂ ), zirconium oxide (ZrO ₂ ), antimony oxide (Sb ₂ ). O ₅ ), iron oxide (Fe ₂ O ₃ ), or zirconium oxide-doped titanium oxide, a rare earth oxide, or the like can be given. Silica is particularly suitable for a coating agent for scratch resistance. When used as a hard coat agent, the amount of the metal oxide fine particles added is preferably 5 to 500 parts by weight, and particularly preferably 10 to 200 parts by weight, based on 100 parts by weight of the organopolysiloxane resin.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION The organopolysiloxane resin composition of the present invention has an average compositional formula of R ¹ _n Si (OR
² ) 100 parts by weight of a siloxane resin represented by _p (OH) _q O _{(4-n-p-q) / 2} , and tert-butano
Alcohol, tert-amyl alcohol, methyl isobutyl
It can be easily obtained by mixing 40 to 2,000 parts by weight of at least one organic solvent selected from ketone (MIBK) .

[0035]

INDUSTRIAL APPLICABILITY The present invention improves the storage stability of an organopolysiloxane resin composition by containing an organic solvent having a specific relative dielectric constant, so that it is not necessary to store it at low temperature as before. It can be easily transported and stored. Further, by adding metal oxide fine particles, the organopolysiloxane resin composition of the present invention can be suitably used as a hard coat agent.

[0036]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.
Further, unless otherwise specified, “parts” and “%” described below mean “parts by weight” and “% by weight”, respectively.

EXAMPLE 1 Into a 1-liter flask, 272 g (2.0 mol) of methyltrimethoxysilane and 157 g of methanol (relative permittivity: 32.6, 25 ° C.) were placed, and the mixture was ice-cooled in a nitrogen atmosphere at 10 ° C. Below. Then 0.1
An equivalent amount of acetic acid aqueous solution (144 g, 8.0 mol) was added dropwise over 40 minutes to hydrolyze methyltrimethoxysilane. After completion of the dropwise addition, the mixture was reacted for 1 hour under ice cooling and then stirred at room temperature for 3 hours to complete hydrolysis.

191 g of methanol silica sol (silica solid content 30% by weight) and te were added to the obtained silanol solution.
600 g of rt-butanol was added, and stripping was performed under a reduced pressure of 10 to 20 mmHg while keeping the internal temperature at 35 ° C. or lower to distill off methanol and residual water. The obtained concentrated silanol liquid was 653 g.

Tert- was added to the obtained concentrated silanol solution.
111 g of butanol was added, and the siloxane solid content was 25
It was prepared so as to have a weight percentage. When the methanol: tert-butanol ratio in the solvent was measured by gas chromatography, it was 10:90. A coating solution was prepared by adding 0.5% by weight of sodium acetate to the siloxane solid content in this solution.

Example 2. tert-butanol
A siloxane solid content of 25% by weight was prepared in exactly the same manner as in Example 1 except that t-amyl alcohol was used. As a result, a coating liquid containing 8% by weight of methanol in the solvent was obtained. .

Comparative Example 1. A flask of 3 liters was charged with 272 g (2.0 ml) of methyltrimethoxysilane and 157 g of ethanol (dielectric constant: 24.3, 25 ° C.) and cooled under ice in a nitrogen atmosphere at 10 ° C. or less. And Then 0.1N
144 g (8.0 mol) of the acetic acid aqueous solution of was added dropwise over 40 minutes to carry out hydrolysis. After completion of the dropwise addition, the mixture was reacted under ice cooling for 1 hour and then stirred at room temperature for 3 hours to complete hydrolysis.

To the obtained silanol solution, 191 g of methanol silica sol (silica solid content: 30% by weight) was added and stirred at room temperature for 2 hours, and after aging, 600 g of ethanol was added.
In addition, while keeping the internal temperature below 40 ° C, 30-40m
Methanol and ethanol were distilled off under reduced pressure of mHg. By repeating this operation twice, the siloxane solid content becomes 3
528 g of a 6.2 wt% concentrated silanol solution were obtained. Then, add ethanol 23 to adjust the solid content to 25% by weight.
When 7 g was added, the methanol: ethanol ratio in the solution was 12:88. Further, 0.5 wt% of sodium acetate was added as a curing catalyst to the siloxane solid content to prepare a coating liquid.

Comparative Examples 2 and 3. The coating liquid of Comparative Example 2 was subjected to hydrolysis in exactly the same manner as Comparative Example 1 except that methanol was used instead of ethanol used as a solvent of the alkoxysilane solution before hydrolysis and solvent replacement by stripping was not performed. Was prepared. Further, hydrolysis was carried out in the same manner as in Comparative Example 1 except that ethanol used as a solvent of the alkoxysilane solution before hydrolysis was replaced with isopropyl alcohol to prepare a coating liquid of Comparative Example 3.

Regarding the storage stability of the coating solutions of Examples 1 and 2 and Comparative Examples 1 to 3 at a temperature of 25 ° C.,
Immediately after preparation and after storage for 1 month after preparation, the coating liquid was applied and cured, and various physical properties of the coating film were evaluated in the following manner for comparison. The results are shown in Table 1 below. As the coating, a polycarbonate plate coated with a primer layer made of a thermosetting acrylic resin, cured at 120 ° C. for 30 minutes, coated with the coating liquid prepared above, and cured at 120 ° C. for 1 hour. Was used.

[0045]

[Table 1]

Evaluation method-Appearance of liquid: A clear, colorless and transparent coating liquid was regarded as good, and a liquid in which white turbidity or white solid was deposited was regarded as poor. -Appearance of coating: The transparency of the obtained coating when the coating liquid was applied and cured was visually evaluated.

Pencil hardness: JIS: K-5400 8.
The evaluation was performed according to Section 4.2. Specifically, the coating liquid is applied to a polished steel plate and cured at 120 ° C. for 1 hour, and a pencil is firmly pressed against the coating film at an angle of 45 degrees, and is moved forward by a certain force. The hardness of a pencil (9H to 6B) having a groove on the coating was evaluated.

Adhesion: JIS: K-5400 No. 6.1
Evaluation was performed according to item 5. Specifically, use a knife to coat 1
The cuts were made at intervals of mm, and 11 grids were prepared in each of the vertical and horizontal directions. When the cellophane tape (product of Nichiban Co., Ltd.) was adhered and then peeled off, the number of squares which were not peeled off was evaluated. -Scratch resistance: Steel wool # 0000 was used to rub the coating surface 10 times with a load of 500 g, and the appearance of scratches was visually determined. The criteria for judgment are as follows: ○: scratches that are hardly scratched, and ×: scratches.

Example 3.1 In a 1 liter flask, 136 g (1.0 mol) of methyltrimethoxysilane and te were added.
rt-Butanol (relative permittivity 10.9, 30 ° C) 220
g and ice-cooled under a nitrogen atmosphere to 10 ° C or lower.
Next, 72 g (4.0 mol) of 0.05N hydrochloric acid aqueous solution was added to 30
Hydrolysis was carried out by dropping the solution over a period of minutes. Then, the mixture was left under ice-cooling for 30 minutes and then stirred at room temperature for 2 hours to complete hydrolysis.

²⁹ Si-NMR of the resulting hydrolyzate solution
(59.6 MHz) was measured (FIG. 1). Then, the solution was coated on a glass substrate and dried at 60 ° C. for 15 minutes to completely evaporate the solvent component, and the infrared absorption spectrum of the thin film formed was measured. The residual amount of methoxy groups was determined from the measurement results and found to be 0.2% by weight (FIG. 2).

Two signals (-47 pp in FIG. 1)
m and -56 ppm) are assigned to the signal of a silicon atom having a hydroxyl group or a methoxy group. From these signal intensity ratios, the residual methoxy group and silanol group contents can be calculated, and the average composition formula MeSi (OM
_{e) P (OH) q O} (3-Pq) / 2 in the p + q is 0.6
3 was obtained (see Table 2 below).

[0052]

[Table 2] ─────────────────────────────────── Chemical shift structure Abundance ratio ────── ───────────────────────────── −47ppm MeSi (OX) ₂ O _0.5 4.8mol% −56ppm MeSi (OX) ₁ O _1.0 53.5 mol% −64 ppm MeSiO _1.5 41.7 mol% ─────────────────────────────────── ─

In FIG. 2, the broad absorption at 3,200 cm ⁻¹ is the stretching vibration of the hydrogen-bonding silanol group OH, and the extremely weak absorption at 2,840 cm ^{−1 is} the absorption of C—H at the methoxy group. It is derived from stretching vibration. Regarding the hydrolyzed condensate of methyltrimethoxysilane, the amount of residual methoxy groups can be quantified from the intensity ratio of the C—H stretching vibration of the methyl group and the C—H stretching vibration of the methoxy group.

From FIG. 2, it is estimated that the methoxy group is 0.2% by weight. Therefore, the values of p and q can be calculated from MeSi (O
When calculated in Me) _P (OH) _q O _{(3-Pq) / 2} ,
Since p is 0.01 or less and can be equal to 0, q = 0.63, and the average composition formula of the resin of Example 3 can be expressed as MeSi (OH) _0.63 O _1.19 .

While maintaining this silanol solution at 25 ° C., using gel filtration chromatography (GPC),
The change in the molecular weight distribution over time was traced to obtain a GPC curve immediately after hydrolysis (Fig. 3). The GPC curve in FIG. 3 is divided into T1 to T5 peaks due to the difference in the degree of polymerization, but since the silanol condensation reactivity increases as the molecular weight increases, T1, T2, T3 from the low molecular weight peak. T4
And T5.

Comparative Examples 4-7. tert-butanol was made to correspond to Comparative Examples 4 to 7,
Methanol (relative permittivity 32.6, 25 ° C), acetylacetone (relative permittivity 25.7, 20 ° C), acetone (relative permittivity 20.7, 25 ° C) and dioxane (relative permittivity 2.2, 25), respectively. The hydrolysis was completed in exactly the same manner as in Example 3 except that the temperature was changed to 0 ° C). Then, while the obtained silanol solution was stored at 25 ° C., changes in the molecular weight distribution were traced by GPC.

The changes in the five molecular weight distributions of Example 3 and Comparative Examples 4 to 7 were changed to T2 to T4 (A: square) and T5 or more (B: rhombus) except for T1 of the GPC curve shown in FIG. ) Of the two sets of peak area ratios (25 days) were used for graphing (FIG. 4). In FIG. 4, it was observed that the condensation of silanol groups gradually proceeded as the number of days passed, and the ratio of A decreased and B increased due to the increase in the molecular weight.

Therefore, regarding the stability of the silanol group, B is A
The larger the number of days, or the smaller the area difference between A and B on the 25th day, the larger the number of days, and the stability of the silanol group was judged from the change in each peak area. From the results, the polymerization rate of the silanol group-containing siloxane resin in each solvent was found to be tert-butanol>
It was found that THF>dioxane>acetone> methanol≈acetylacetone.

Furthermore, 95.7 g of methanol silica sol (solid content 30%) was added to 428 g (solid content about 20%) of the hydrolyzed solutions of Example 3 and Comparative Examples 4 to 7 to allow the hydrolysis reaction to proceed completely. . Next, except for Comparative Example 4, since the methanol content of the solution was about 31%, the total solid content of the final liquid was about 15%, and the methanol content was 10%.
Solvents were added as appropriate so that:

Then, the entire hydrolyzed solution containing Comparative Example 4 was heated to 10 to 20 while keeping the internal temperature at 35 ° C. or lower.
The solvent ratio was adjusted by stripping methanol under reduced pressure of mmHg to remove methanol. Incidentally, since the organic solvent of Comparative Example 4 is methanol, it is not necessary to add the above-mentioned various solvents, and in Comparative Example 6, since the volatility of acetone is extremely high, first, after adding a large amount of acetone, The strips were pretreated by stripping them under the same conditions.

Furthermore, 0.5% sodium acetate as a curing catalyst was added to the siloxane solids to prepare a coating solution, which was applied to an aluminum substrate and cured by heating at 150 ° C. for 30 minutes to form a coating film. Obtained. The storage stability of these coating liquids at 25 ° C was compared by coating and curing the coating liquid immediately after preparation and after storage for 1 month after preparation, and evaluating various physical properties of the coating film in the same manner as the above-mentioned criteria. did. The results are shown in Table 3 below.

[0062]

[Table 3]

Examples 5 and 6 and Comparative Examples 8 to 10 408 g of methyltrimethoxysilane in a 10.2 liter flask.
(3.0 mol) and add water 786 at 0 ° C under nitrogen atmosphere.
g (43.7 mol) was added and mixed well. Then, under ice cooling, 216 g (12.0 mol) of 0.05 N hydrochloric acid aqueous solution
Was added dropwise over 40 minutes for hydrolysis. After completion of the dropwise addition, the mixture was stirred at 10 ° C. or lower for 1 hour and at room temperature for 2 hours to complete hydrolysis.

The methanol produced by hydrolysis is heated to 70 ° C.
The solution was distilled off under reduced pressure at 60 mmHg for 1 hour, and the solution concentrated to 88% was cloudy, and when left standing overnight, it was separated into two layers. After removing 996.6 g of water in the upper layer by decantation, the viscous polyorganosiloxane resin 240.
0 g was obtained. From the result of ²⁹ Si-NMR measurement of the obtained resin, it was calculated that the silanol group content was 7.8% (0.32 per 1 silicon atom) in the same manner as in Example 3.

4 g of each of the above siloxane resins (10.0 g) corresponding to Examples 5 and 6 and Comparative Examples 8 to 10 were prepared.
A silanol-containing siloxane resin solution was prepared by adding 0.0 g of tert-butanol, methyl isobutyl ketone, acetoniryl, acetone, and dioxane. After being stored at room temperature for 2 weeks, G
Table 4 shows the results of comparing the molecular weight distributions immediately after solution preparation and after 2 weeks by PC.

[0066]

[Table 4]

Examples 7 and 8 and Comparative Examples 11 to 14. To the silanol group-containing siloxane resin 10.0 g synthesized in Examples 5 and 6 and Comparative Examples 8 to 10, corresponding to Examples 7 and 8 and Comparative Examples 11 to 14, respectively, 40.0 g of tert-butanol, tert-amyl alcohol,
A silanol-containing siloxane resin solution was prepared by adding an alcohol solution of methanol, isopropyl alcohol, n-butanol, and isobutanol. 2 at room temperature
After storage for a week, GPC was performed in the same manner as in Example 3 above.
Table 5 shows the results of comparing the molecular weight distributions immediately after the solution preparation and after 2 weeks.

[0068]

[Table 5]

[Brief description of drawings]

FIG. 1 ²⁹ S of the siloxane resin solution prepared in Example 3
i-NMR chart.

FIG. 2 is an infrared absorption spectrum chart of the thin film prepared in Example 3 in which the siloxane resin solution was completely distilled off.

FIG. 3 is a GPC curve of the hydrolysis / condensation product of Example 3.

FIG. 4 is a graph showing a change with time of a ratio of peak areas of a GPC curve.

[Explanation of symbols]

□: Area of peak from T2 to T4 (A) ◇: Area of peak above T5 (B)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C08L 83/06 C09D 183/06 C09D 183/06 C08K 5/15 (56) Reference JP-A-61-89281 (JP, A) JP 61-19660 (JP, A) JP 9-20866 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 83/06 C08K 5/05-5/07 , 5/15 C09D 183/06

Claims (3)

(57) [Claims] 1. An average composition formula, R ¹ _n Si (OR ² ).
100 parts by weight of siloxane resin represented by _p (OH) _q O _{(4-n-p-q) / 2} , and tert-butano
, Tert-amyl alcohol, methyl isobutyl ketone
An organopolysiloxane resin composition containing 40 to 2,000 parts by weight of at least one organic solvent selected from tons (MIBK) . However, R in the above average composition formula
¹ is a hydrogen atom or an organic group having 1 to 18 carbon atoms, R
² is an alkyl group having 1 to 6 carbon atoms, n, p and q are
0 ≦ n ≦ 1.8, 0 ≦ p ≦ 1, 0.2 ≦ q ≦
3 and a number satisfying 0.8 ≦ n + p + q <4. 2. A siloxane resin as a curing catalyst.
A contract containing 0.01 to 10 parts by weight per 100 parts by weight.
The siloxane resin composition according to claim 1. 3. A metal oxide fine particle is added to the white powder.
A contract containing 5 to 500 parts by weight per 100 parts by weight of sun
The siloxane resin composition according to claim 1 or 2.