JPH05125187A - Polyorganosilsesquioxane and its production - Google Patents

Abstract

PURPOSE:To obtain a polyorganosilsesquioxane having ultra-high-molecular weight, providing a coating film having excellent toughness, hardness and heat resistance without curing under heating. CONSTITUTION:An initial hydrolyzate condensate of a trialkoxysilane or trichlorosilane is heated in an organic solvent (e.g. methanol or ethanol) in 0.5-30wt.% solid content concentration by using an alkali (e.g. sodium hydroxide) as a catalyst at 60-140 deg.C and condensed to produce a polyorganosilsesquioxane of the formula [50-100mol % whole side chain R1 is methyl group and the rest is 2 or 3C alkyl or (substituted) phenyl; R2 is 1-3C alkyl or H; (n) is integer], having >=100,000 number-average molecular weight.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an ultrahigh molecular weight polyorganosilsesquioxane having a ladder-like molecular structure and exhibiting excellent properties in terms of heat resistance, hardness, insulation and the like, and a method for producing the same. Regarding

[0002]

2. Description of the Related Art A group of highly heat-resistant resins such as polyimide has been developed with the development of space, and recently, in order to meet the demands for smaller size, lighter weight and higher performance in the fields of electric and electronic industries, further development of automobile industry With the progress of weight reduction and the like, the market has expanded significantly, and the demand for heat-resistant resins is increasing more and more, and further improvement in heat resistance is required.

However, it is unavoidable that the carbon skeleton plastic has a certain limit in terms of heat resistance, and in that respect, the silicon skeleton plastic material has a possibility of realizing higher performance. I have a secret.

By the way, polyorganosilsesquioxane known by the abbreviation of ladder silicone has a siloxane skeleton-bonded molecule having a fixed movement and has a skeleton structure similar to silica, and has a purpose of hardness, heat resistance and the like. Has an ideal structure for. In particular, polymethylsilsesquioxane having a methyl side chain exhibits particularly inorganic properties in terms of molecular structure and has high hardness and heat resistance.

However, it is also known that polyorganosilsesquioxanes having a majority of side chains as described above having a methyl group have many obstacles in their synthesis and are problematic in widespread use. .. One of the reasons is that polymethylsilsesquioxane has less steric hindrance due to side chains and the reactivity of silanol and alkoxy groups as terminal groups is high, and it is known that gelation easily occurs during synthesis or storage. .. For this reason, high molecular weight compounds have not been synthesized so far, and only oligomers have been commercialized (trade name; Glass Resin USA OI-NEG).
Company).

The solution of the above oligomer is coated on a substrate such as metal or plastic, and when the solvent is volatilized and heated, dehydration between silanol groups and alkoxy groups of the terminal groups and three-dimensional curing by condensation reaction involving dealcoholization. Therefore, it is used as a coating film. Although this coating has high hardness and heat resistance, it is extremely brittle and cannot follow the large deformation of the base material, which is the second problem. Therefore, it is practically used only as a thin film of about several microns. Has been done.

A third problem is that heat curing is indispensable for three-dimensional curing as described above.
In practice, there are restrictions on the application temperature depending on the substrate used, and it takes a long time to cure, which also leads to problems in terms of cost and process.

[0008]

The present invention has been made for the purpose of solving the above-mentioned problems of polyorganosilsesquioxane having a side chain mainly composed of a methyl group, and has an ultrahigh molecular weight, An object of the present invention is to provide a new polyorganosilsesquioxane exhibiting toughness, hardness, and heat resistance without heat curing and a method for producing the same.

[0009]

Means for Solving the Problems The present inventors have conducted extensive studies to achieve the above object, and as a result, the above object is satisfied by a polyorganosilsesquioxane having a specific skeletal structure and an ultrahigh molecular weight. This has led to the completion of the present invention. That is, the present invention provides a polyorganosilsesquioxane represented by the general formula (I),
50 to 100 mol% of all side chains R ₁ are methyl groups, the remaining side chains are alkyl groups having 2 to 3 carbon atoms or substituted or unsubstituted phenyl groups, and have a number average molecular weight of 10
The present invention relates to a polyorganosilsesquioxane having a content of 50,000 or more.

[0010]

[Chemical 2]

[In the general formula (I), R ₂ represents an alkyl group having 1 to 3 carbon atoms or a hydrogen atom, and n
Is an integer. ]

In the present invention, trialkoxysilane or an initial hydrolysis-condensation product of trichlorosilane is used as a raw material in an organic solvent at a solid content concentration of 0.5 to 30% by weight with an alkali as a catalyst and a concentration of 60 to 140. The present invention relates to a method of producing the above polyorganosilsesquioxane by heating at 0 ° C. and further condensing.

The present invention will be described in detail below. In the polyorganosilsesquioxane of the present invention represented by the general formula (I), the side chain R ₁ represents an alkyl group having 1 to 3 carbon atoms or a substituted or unsubstituted phenyl group, of which 50 mol%
It is necessary that 80 mol% or more, preferably 80 mol% or more, be a methyl group. When the methyl group content is 50 mol% or less, the heat resistance and hardness aimed at by the present invention are unsatisfactory. The side chain R ₁
As the remaining groups other than the methyl group, an alkyl group having 4 or more carbon atoms is not preferable because it adversely affects the heat resistance.

In the polyorganosilsesquioxane of the present invention, R ₂ which represents an end group is an alkyl group having 1 to 3 carbon atoms or a hydrogen atom, and these are derived from trialkoxysilane or trichlorosilane as a raw material. Is. When a trialkoxysilane having 4 or more carbon atoms is used as a raw material, the hydrolysis and condensation rates are slow and impractical. End groups such as trimethylchlorosilane,
It is also possible to enhance the storage stability by capping with trimethylmethoxysilane or the like before use.

The number average molecular weight of the polyorganosilsesquioxane of the present invention is measured by using a GPC device and a standard molecular weight substance, and it is necessary that the number average molecular weight is 100,000 or more. .. When the number average molecular weight is 100,000 or less, the coating becomes sticky and solvent resistance and surface hardness become insufficient even after the solution is applied to the substrate and the solvent is volatilized, which is not preferable.

In order to produce the polyorganosilsesquioxane of the present invention, first, the corresponding raw material trialkoxysilane or trichlorosilane is hydrolyzed and condensed to form an initial condensate. As the catalyst for this initial hydrolysis and condensation, either an acid catalyst or an alkali catalyst can be used, and an acid catalyst is preferred from the viewpoint of easy control of the reaction. Then, the initial condensate is treated with an organic solvent to obtain a solid content concentration of 0.5 to 3
60-140 with alkali as a catalyst at a concentration of 0% by weight
The condensation is further advanced by heating to 0 ° C. so that the number average molecular weight becomes 100,000 or more.

In the present invention, as the organic solvent at the time of condensation, alcohols such as methanol, ethanol, isopropanol, butanol, etc., ethers such as tetrahydrofuran, diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, methyl ethyl ketone, acetone, methyl isobutyl ketone. Ketones such as ethyl acetate, methyl acetate,
Esters such as butyl acetate, toluene, xylene,
Examples thereof include aromatic hydrocarbons such as benzene and chlorobenzene, halogenated hydrocarbons such as dichloroethane, trichloroethane and trichloroethylene, and solvents such as dimethylformamide and dimethylsulfoxide.

Sodium hydroxide is used as a catalyst for condensation.
Alkali metal hydroxides such as potassium hydroxide, lithium hydroxide, cesium hydroxide, amines such as triethylamine, diethylenetriamine, n-butylamine, P-dimethylaminoethanol, triethanolamine, and tetramethylammonium hydroxide. Quaternary ammonium salts can be used.

In producing the polyorganosilsesquioxane of the present invention, the solid content concentration is 3 with respect to the above-mentioned organic solvent.
The content is preferably 0% by weight or less, and at a solid content concentration higher than this, gelation easily occurs as the condensation proceeds. Even if gelation is avoided, the product has poor storage stability, and gelation easily occurs during storage. On the other hand, at a concentration of 0.5% by weight or less, the condensation reaction rate is slow, which is not practical.

The temperature of the condensation reaction is preferably 60 to 140 ° C., the reaction cannot proceed efficiently at 60 ° C. or lower, and conversely it is difficult to suppress gelation at 140 ° C. or higher. The condensation reaction is stopped by neutralizing the reaction solution, and the salt generated at that time is removed by filtration or washing with water as necessary. If a trace amount of water is a problem, it can be removed by using a dehydrating agent. Another by-product of the condensation reaction, alcohol, can be easily removed by heating or vacuum distillation. In this way, the polyorganosilsesquioxane of the present invention can be stably produced without gelation.

In using this polyorganosilsesquioxane, it is possible to use it as a solution as it is, by concentrating, diluting, etc. and modifying the solvent composition, or by using it as a film or powder form without any solvent. You can also take it out. In addition, various additives such as fillers, dyes, pigments, stabilizers, ultraviolet absorbers, antifungal agents, surfactants, and leveling agents may be added to the polyorganosilsesquioxane of the present invention as necessary. It can also be used.

The polyorganosilsesquioxane of the present invention can form a tough, hard and heat-resistant coating at 500 ° C. only by coating the surface of the substrate with the solution and evaporating the solvent. However, it is possible to further improve hardness, solvent resistance and the like by heating and curing this coating.

[0023]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The basic physical properties of the polyorganosilsesquioxanes used in Examples and Comparative Examples were measured by the following methods.

[Number average molecular weight] According to the GPC method. The equipment is Shimadzu CR-3A and the column is Showdex KF801, KF802, KF made by Showa Denko KK
803 and KF804 were connected and used, and it calculated | required by the comparison conversion with standard sample polystyrene.

[Infrared absorption spectrum] Shimadzu I
The infrared absorption spectrum was investigated by measuring the transmittance using R-435.

[X-ray diffraction] RIGAK manufactured by Rigaku Denki Co., Ltd.
The U ROD-B system (the X-ray source is a Cu target) was used.

(Example 1) 481.4 g (2.7 mol) of methyltriethoxysilane and 59.5 g (0.3 mol) of phenyltrimethoxysilane were placed in a 1-liter four-necked flask.
Mol), hydrochloric acid 0.0004 mol, water 108 g (6 mol)
After charging, the temperature in the flask was raised to 50 ° C.,
Hold for 30 minutes with stirring. Subsequently, the temperature was raised to 70 ° C., the reaction was carried out for 2 hours, and then water and alcohol were removed using an evaporator to obtain about 260 g of a reaction product. Next, this was dissolved in methyl isobutyl ketone so that the solid content concentration was 15% by weight, and triethylamine was added to 0.003%.
After adding 82 mol dropwise and reacting at 80 ° C. for 3 hours, 0.0087 mol of hydrochloric acid was added to neutralize.

When the molecular weight of this reaction product was determined by GPC, the number average molecular weight was 350,000. GP
The molecular weight distribution of this reaction product as seen from the C elution curve was narrower than that of general silicone compounds. The solution was spin-coated on a silicon wafer and the solvent was completely removed.
Stretching vibration of O-Si is 1030 cm ^-1 and 1100 cm ^-1
The structure of polysilsesquioxane was confirmed by branching to and. For the attribution of this spectrum, see
The description on page 35 of the Abstracts of Inorganic Polymer Lectures was cited and conformed.

The X-ray diffraction pattern of the above film is 4.5.
It has a clear diffraction peak at Å, which agrees with the value measured by Brown et al. For polysilsesquioxane.

The above film was a relatively hard coating having a pencil hardness of H, and a coating coated on a thin metal plate showed flexibility capable of following 180-degree bending. Moreover, this was heat-treated at 500 ° C. for 1 hour, but no damage was observed, and the pencil hardness was improved to 6H.

(Comparative Example 1) Polyorganosilsesquioxane was synthesized by the same operation and formulation as in Example 1 except that the solid content concentration at the time of condensation was 0.2% by weight. The number average molecular weight by GPC of the reaction product after 3 hours at 80 ° C. was 50,000. This solution was concentrated to a solid content concentration of 15% and spin-coated on a silicon wafer in the same manner as in Example 1 to completely remove the solvent, but the film was sticky and no hardness was obtained at all.

Comparative Example 2 A polyorganosilsesquioxane was synthesized by the same operation and formulation as in Example 1 except that the solid content concentration during condensation was 35% by weight. The number average molecular weight of the reaction product after 3 hours at 80 ° C. is 65.
After being stored at room temperature, the solution gelled.

Comparative Example 3 The same operation as in Example 1 except that the reaction temperature at the time of condensation is 50 ° C.
Polyorganosilsesquioxane was synthesized by the formulation. The number average molecular weight of the reaction product after 3 hours was 62,000, which did not reach the target molecular weight range of the present invention.

(Comparative Example 4) In Example 1, the solvent at the time of condensation was cyclohexanol, and the reaction temperature at the time of condensation was 145.
Polyorganosilsesquioxane was synthesized by the same operation and formulation as in Example 1 except that the temperature was changed to ° C. After 2 hours of reaction, gelation occurred and precipitation occurred.

(Example 2) In a 1-liter four-necked flask, 320.9 g (1.8 mol) of methyltriethoxysilane and 247.6 g (1.
(2 mol), 0.0004 mol of hydrochloric acid, and 108 g (6 mol) of water were charged, and then the temperature in the flask was raised to 50 ° C. and kept for 30 minutes while stirring. Subsequently, the temperature was raised to 70 ° C., the reaction was carried out for 2 hours, and then water and alcohol were removed using an evaporator to obtain about 270 g of a reaction product. Next, this was dissolved in butyl acetate so that the solid content concentration was 5% by weight, 0.0082 mol of ethanolamine was added dropwise, and the mixture was reacted at 70 ° C. for 5 hours, and then 0.008% of acetic acid was added.
7 mol was added to neutralize. The molecular weight of this reaction product is determined by GPC
The number average molecular weight was 1,150,00.
It was 0. When a silicon wafer was spin-coated and the solvent was completely removed in the same manner as in Example 1, a relatively hard coating having a pencil hardness F was obtained. Further, this coating was heat-treated at 300 ° C. for 1 hour, but no abnormality was found and the pencil hardness was improved to 2H.

(Comparative Example 5) A polyorganosilsesquioxane was prepared in the same manner as in Example 1 except that 1.2 mol of methyltriethoxysilane and 1.8 mol of propyltriethoxysilane were used in Example 2. Was synthesized.
The number average molecular weight after 3 hours of reaction was 980,000. The film produced on a silicon wafer has a pencil hardness of 2B.
It was soft, and when heat-treated at 300 ° C. for 1 hour, many cracks were generated.

[0037]

As described above, the polyorganosilsesquioxane of the present invention is tough, has high hardness, and is heat resistant to withstand 500 ° C. only by coating the solution with the substrate and evaporating the solvent. Can be formed. Therefore, the process is simple, and it can be applied to a base material which is not suitable for conventional heat curing, and can be used for a wide range of purposes.

Claims (2)

[Claims] 1. In the polyorganosilsesquioxane represented by the general formula (I), 50 to 50% of all side chains R ₁ are used.
100 mol% is a methyl group, the remainder is an alkyl group having 2 to 3 carbon atoms or a substituted or unsubstituted phenyl group, and R ₂ is an alkyl group having 1 to 3 carbon atoms or a hydrogen atom, n is an integer and the number average molecular weight is 1
A polyorganosilsesquioxane having a content of at least 0,000. [Chemical 1] 2. A trialkoxysilane or an initial hydrolysis-condensation product of trichlorosilane is used as a raw material and heated to 60 to 140 ° C. in an organic solvent at a solid content concentration of 0.5 to 30% by weight with an alkali as a catalyst. The method for producing a polyorganosilsesquioxane according to claim 1, wherein the polyorganosilsesquioxane is further condensed.