JPH10152561A - Production of polysiloxane, polysiloxane coating and inorganically insulated wire having the same coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject compound capable of forming inorganic polymers having strong heat resistance and moisture resistance by reacting a difunctional silicon compound with a boron compound and then reacting a trifunctional silicon compound and a boron compound with the above reaction product. SOLUTION: This polysiloxane is obtained by reacting (A) a compound of formula I (R is an alkyl, an alkenyl or an aryl; X is an alkoxy, hydroxyl, a halogen) with (B) a boron compound, then the obtained reaction product with (C) a compound of formula II and the component B. The above mentioned reaction is preferably carried out until the component A and the component B are converted to a condensate containing 2-10, especially 2-5 borosiloxane units in average and the reaction time required to satisfy the purpose is 1-8 hours. Thus, the obtained product is expected to have high flexibility, express no adhesiveness by baking at a relatively low temperature and reduce little weight by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyborosiloxane, and more particularly, to a method having a high flexibility and a non-sticky property by firing at a relatively low temperature. And a method for producing a polyborosiloxane capable of forming an inorganic polymer having high heat resistance.

[0002]

2. Description of the Related Art Polyborosiloxane is a polymer having a structure in which siloxane bonds are linked via boron. It is known that polyborosiloxane can form an inorganic polymer having excellent heat resistance by firing, and is used for an insulating coating of an electric wire requiring heat resistance.

[0003] In polyborosiloxane, boron has a three-coordinate structure and a certain degree of three-dimensional network structure is formed. Therefore, cyclization of the siloxane during heating is prevented from falling off, and the boron is formed from a bifunctional alkoxysilane. Higher heat resistance than polysiloxane or the like. In addition, since the siloxane compound can be produced by condensing the boron compound itself that condenses with the catalyst as a catalyst, there is no need to remove the catalyst later. ing.

Since polyborosiloxane is excellent in various properties as described above, it is expected to be particularly useful as an insulating coating requiring high heat resistance, but has further advantages in handling and manufacturing. Is desired. For example, in addition to the high heat resistance of the formed inorganic polymer, if it has sufficient flexibility before firing, it is easy to handle after forming the film and can be processed. Also,
From the viewpoint of the heat resistance and the like of the formed inorganic polymer, it is preferable that the heating loss during firing is small, and it is preferable that the inorganic polymer has excellent moisture resistance from the viewpoint of durability. Furthermore, if an inorganic insulating film having no low molecular weight components and no stickiness even when calcined at a low temperature is obtained, it is advantageous in production.

[0005] However, for example, polydimethylborosiloxane is excellent in flexibility, but remains sticky when calcined at a low temperature of about 200 ° C, and has a higher heat resistance because methyl groups are dropped off even at a temperature of 300 ° C or less. It is not enough for the required use. Further, it has poor moisture resistance due to hydrolysis of boron. Further, polydiphenylborosiloxane improves tackiness, heat resistance, moisture resistance, and the like at low temperature firing, but is inferior in flexibility.

It is also known that polydiphenylborosiloxane is condensed using silicone oil. The polymer obtained in this way has improved heat resistance, moisture resistance and flexibility. Since firing at a low temperature causes the silicone oil to remain and become sticky, firing at a high temperature is necessary.

Further, it is known that a three-dimensional network structure is formed by using a silicon component such as a trifunctional siloxane, but flexibility cannot be obtained by using only a trifunctional silicon component.
Even when a bifunctional silicon component is used in combination, simply reacting the bifunctional and trifunctional silicon components together with the boron compound at the same time results in a non-uniform structure due to the high reactivity of the trifunctional silicon component. In this case, a material having sufficient properties such as partially inferior flexibility could not be obtained.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to an inorganic polymer which has high flexibility, does not show stickiness even when fired at a relatively low temperature, has a small loss on heating, and has high heat resistance and moisture resistance. It is an object of the present invention to provide a method for producing a polyborosiloxane capable of forming a polyborosiloxane.

[0009]

As a result of the study of the present inventors, when producing a polyborosiloxane using a bifunctional and trifunctional silicon compound and a boron compound, first, the bifunctional silicon compound is It has been found that a polyborosiloxane satisfying the above-mentioned desired properties can be obtained by reacting with a boron compound and further reacting the obtained compound with a trifunctional silicon compound and a boron compound.

Accordingly, the present invention provides the following formula (a)

[0011]

Embedded image (Wherein R represents an alkyl group, an alkenyl group or an aryl group, and X represents an alkoxy group, a hydroxyl group or a halogen atom), and the resulting product is further reacted with a boron compound according to the following formula ( b)

[0012]

Embedded image (Wherein, R and X have the same meanings as described above) and a boron compound.

In a preferred embodiment of the method of the present invention, the compound of the formula (a) and the boron compound are represented by the following formula (c)

[0014]

Embedded image (Wherein R represents the same meaning as described above). The compound of the formula (a) is reacted with the boron compound until the unit is converted into a condensed compound containing 2 to 10 units on average. In the above method of the present invention, it is preferable to add the compound of the formula (b) in the liquid state to the reaction product of the compound of the formula (a) in the liquid state and the boron compound.

The present invention also provides a coating film obtained by applying and baking a coating containing polyborosiloxane produced by the above method, and an inorganic insulated wire having such a coating film as an insulating coating. .

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The compound of the formula (a) used in the method for producing a polyborosiloxane of the present invention is the same bifunctional silicon compound as that conventionally used for producing polysiloxane, polyborosiloxane and the like. .

R in the formula (a) is an alkyl group, an alkenyl group or an aryl group, preferably having 1 to 1 carbon atoms.
0, more preferably an alkyl group having 1 to 5 carbon atoms, particularly preferably 1 to 3 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms, particularly preferably 2 to 2 carbon atoms.
3 alkenyl groups, or preferably 6 to 18 carbon atoms,
More preferably, it is an aryl group having 6 to 12 carbon atoms. R
Preferred examples include, but are not limited to, a methyl group, an ethyl group, a propyl group, a butyl group, a vinyl group, a phenyl group and the like.

X in the formula (a) is a functional group, which is an alkoxy group, a hydroxyl group, or a halogen atom. The alkoxy group used as X preferably has 1 to 1 carbon atoms.
10, more preferably an alkoxy group having 1 to 4 carbon atoms, preferably a methoxy group, an ethoxy group, a propoxy group, a butoxy group, etc., which can be removed as an alcohol in a subsequent reaction. The halogen atom is selected from a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and is preferably chlorine.

R and X in the formula (a) each independently represent the above-mentioned groups and the like. In the compound of the formula (a), R and X may be different from each other or the same, The compounds of formula (a) preferably each have the same R and X.

As long as the compound of the formula (a) has two functional groups X, even if it is condensed before reacting with several, for example, about 2 to 5 boron compounds, the effects of the present invention can be obtained. No problem. The compounds of the formula (a) can be used alone or in combination of two or more.

Preferred examples of the compound of the formula (a) include, for example, dimethyldihydroxysilane, diphenyldihydroxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, dimethyldipropoxysilane, diphenyldimethoxysilane, diphenyldimethoxysilane,
Examples include diphenyldipropoxysilane and dehydration condensates thereof.

The compound of the formula (b) used in the method for producing a polyborosiloxane of the present invention is a known trifunctional silicon compound.

In the formula (b), R and X have the same meanings as in the formula (a), X each independently represents the above-mentioned groups and the like, and X in the compound of the formula (b) is different from each other. Or the same, but the compounds of formula (b) preferably have the same X.

The compound of the formula (b) may have been condensed several times, for example, about 2 to 5 before reacting with the boron compound. The compounds of the formula (b) can also be used alone or in combination of two or more.

Preferred examples of the compound of the formula (b) include, for example, methyltrichlorosilane, phenyltrichlorosilane, phenyltrimethoxysilane, phenyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane and the like.

The properties of the resulting polyborosiloxane vary depending on the type of the group R of the compound of the formula (a) and the compound of the formula (b). For example, the larger the amount of the alkyl group as R, the higher the flexibility but the lower the heat resistance.
On the other hand, the larger the amount of an aryl group such as a phenyl group as R, the lower the flexibility but the higher the heat resistance. For example, using a compound of the formula (a) or a compound of the formula (b) having different R in the same compound, or using two or more kinds of the respective compounds, the polymer obtained is
When an alkyl group and an aryl group are included as
The molar ratio of the alkyl group and the aryl group is from 20: 1 to 1:
It is preferably in the range of 1.

The boron compound used in the method of the present invention may be any of those conventionally used to produce polyborosiloxanes, for example, orthoboric acid, metaboric acid,
Boric acid such as boric anhydride, metal borate salts such as borax,
Boric acid esters such as methyl borate, boric acid alkoxides such as trimethoxyboron, and boron halides such as boron chloride can be used.

In the method of the present invention, first, the above formula (a)
Is reacted with a boron compound. The condensation polymerization reaction can be carried out by refluxing these compounds in an inert gas stream, for example, at a temperature in the range of 50 to 150 ° C.

In this case, the compound of the formula (a) (or an oligomer thereof) and the boron compound are used in an amount of 5: 1 to 2: 1 by atomic ratio of silicon to boron, and the following trifunctional silicon compound is used. It is preferable that functional groups such as an alkoxy group remain in such a degree as to be used in the above reaction.

The degree of polymerization of the product of the reaction between the first bifunctional silicon compound and the boron compound affects the properties such as flexibility of the final product. In this reaction, the reaction time is selected. Thus, the degree of polymerization of the condensate obtained can be adjusted, so that the reaction time may be selected so as to give desired properties to the final product.

In order to obtain a polyborosiloxane having desired properties as described above, in the reaction of a compound of the formula (a) (or an oligomer thereof) with a boron compound, both react with the following formula (c)

[0033]

Embedded image (Wherein R has the same meaning as described above) on average 2 to 10, especially 2 to 5 borosiloxane units
It is preferable to carry out the reaction until it is converted into a condensed compound. In order to obtain such a degree of polymerization, depending on other reaction conditions, when the reaction is carried out under the above conditions, a reaction time of 1 to 8 hours may be used.

The degree of polymerization of the condensate of such a bifunctional silicon compound and boron compound can be measured by gel permeation chromatography (GPC), and the specific compound has a desired reaction condition such as a specific reaction temperature. The reaction time for obtaining the degree of polymerization may be measured, and then the reaction time determined from the measurement of the degree of polymerization may be used.

Next, the condensate of the bifunctional silicon compound and the boron compound obtained above is reacted with the trifunctional silicon compound represented by the formula (b) and the boron compound. A trifunctional silicon compound represented by the formula (b) and a boron compound are added to the above-mentioned reaction product of the bifunctional silicon compound and the boron compound, and under the same conditions as in the reaction with the bifunctional silicon compound, preferably 1 By refluxing for more than an hour, substantially all of the functional groups present are reacted. Then, by-products such as alcohol are removed by a distillation operation, and more preferably 100 to 100%.
The temperature is raised to 300 ° C. or higher and aged for 1 hour or more to react unreacted low molecular weight components.

The amount of the trifunctional silicon compound used affects the flexibility of the finally obtained polyborosiloxane, and the higher the amount of the bifunctional silicon compound, the more flexible the polyborosiloxane is obtained. As the amount of the trifunctional silicon compound increases, a stronger polyborosiloxane is obtained, but usually, the ratio of the bifunctional silicon compound to the trifunctional silicon compound is set so that the atomic ratio of silicon is 2: 1 to 5: 1. Is preferred.

The amount of boron compound used with the trifunctional silicon compound is such that the functional groups present are sufficiently reacted and that the boron compound does not exceed the amount required to react the functional groups of the silicon compound. . For example, when boric acid is used as the boron compound, the amount of hydroxyl groups of boric acid should not exceed the amount of functional groups remaining in the silicon compound. The ratio of the trifunctional silicon compound to the boron compound is preferably from 1: 0.1 to 1: 4 in the atomic ratio of silicon to boron.

The reaction product of the compound of the formula (a) with the boron compound and the compound of the formula (b) having a hydroxyl group as X include those which are solid at room temperature. If these compounds are mixed together in a solid state before heating, the reaction proceeds non-uniformly when the temperature is raised, and the structure of the resulting polymer may be non-uniform. Therefore, when the reaction product of the compound of the formula (a) and the boron compound becomes a solid at room temperature, it is maintained in a liquid state without lowering the temperature after the reaction of the compound of the formula (a) and the boron compound. When the compound of the formula (b) is a solid at room temperature, it is heated and melted in advance to obtain a liquid state,
It is preferably added to the reaction product of the compound (a) and the boron compound.

The polyborosiloxane obtained as described above is soluble in a solvent such as ethanol, and is dissolved in such a solvent, and optionally a filler such as an oxide, a carbide, a nitride, or the like. A polymer or the like is added to form an insulating coating, which is applied to the surface where the coating is desired, dried and fired to form an inorganic insulating coating.

The insulating coating material obtained as described above is applied on a substrate such as a conductor wire by a conventional method, and baked at a temperature of about 200 to 500 ° C. for about 2 to 30 minutes. An excellent insulating coating having a heat resistance of 400 ° C. or higher can be obtained. In particular, according to the polyborosiloxane produced by the method of the present invention, a non-sticky film can be formed even when calcined at a low temperature of about 200 ° C.

The inorganic insulated wire thus obtained is also included in the present invention. The thickness of the insulating coating provided on the inorganic insulated wire of the present invention depends on the use of the wire,
Generally, it is about several μm to several mm.

The insulating coating obtained by using the polyborosiloxane produced by the method of the present invention is particularly suitable for forming an insulating coating having heat resistance of electric wires, but is suitable for use in other applications. It can also be used as an insulating coating paint, and can be preferably used, for example, on a precoated (PC) processed plate or the like which is processed after forming an insulating coating.

[0043]

The present invention will be further described with reference to the following examples.

Example 1 36.1 g (0.3 mol) of dimethyldimethoxysilane and 6.18
g (0.1 mol) of boric acid in a flask
Reflux at 80 ° C. for 3 hours. Analysis of the reaction product by GPC indicated that dimethyldimethoxysilane had been converted to a condensate containing on average about 3 borosiloxane units. Next, 13.6 g (0.1 mol) of phenyltrimethoxysilane and 6.18 g (0.1 mol) of boric acid were added thereto, followed by addition of 3%.
Reflux for hours. Thereafter, by-products were removed by a distillation operation, and the mixture was heated and stirred at 200 ° C. for 3 hours to obtain a polyborosiloxane.

Example 2 In place of dimethyldimethoxysilane of Example 1,
A polyborosiloxane was similarly obtained by using the same molar amount of 1,1,3,3-tetramethyl-1,3-dimethoxysilane as a monomer.

After the reaction of 1,1,3,3-tetramethyl-1,3-dimethoxysilane with boric acid, the reaction product was analyzed by GPC, and found to be 1,1,3,3-tetramethyl-1,3 -Dimethoxysilane had been converted to a condensate containing on average about 3 borosiloxane units.

Example 3 A polyborosiloxane was obtained in the same manner as in Example 1 except that 0.25 mol of dimethyldimethoxysilane and 0.05 mol of diphenyldimethoxysilane were used instead of 0.3 mol of dimethyldimethoxysilane.

After the reaction of dimethyldimethoxysilane and diphenyldimethoxysilane with boric acid, the reaction product was subjected to GPC.
As a result, dimethyldimethoxysilane and diphenyldimethoxysilane were converted to a condensate containing on average about 3 borosiloxane units.

Example 4 24.4 g (0.1 mol) of diphenyldimethoxysilane, 4
3.26 g (0.2 mol) of diphenyldihydroxysilane and 6.18 g (0.1 mol) of boric acid were placed in a flask, heated to 110 ° C. with stirring under a stream of nitrogen, melted and maintained at this temperature for 3 hours. Thereafter, the reaction product was analyzed by GPC, and it was found that diphenyldimethoxysilane and diphenyldihydroxysilane were converted to a condensate containing on average about 3 borosiloxane units.

Then, while the above reaction mixture was kept in a molten state, 6.18 g (0.1 mol) of boric acid was added to the flask, and 24.0 g (0.1 mol) of phenyltriethoxysilane was further added to the flask at 1.2 g / 0.1 g using a tube pump. Minutes (0.005 mol / min). After all of the phenyltriethoxysilane had been added, the reaction was heated to 300 ° C. for 1 hour to allow the remaining monomer to react, yielding a polyborosiloxane.

Comparative Example 1 0.28 mol of diphenyldimethoxysilane and 6.18 g (0.
(1 mol) of boric acid was placed in a flask and refluxed at 80 ° C. for 3 hours in a nitrogen stream. Thereafter, by-products were removed by a distillation operation, and the mixture was heated and stirred at 200 ° C. for 3 hours to obtain polydiphenylborosiloxane.

Comparative Example 2 Instead of 0.2 mol of diphenyldimethoxysilane, 0.2
A polydimethylborosiloxane was obtained in the same manner as in Comparative Example 1 except that 2 mol of dimethyldimethoxysilane was used.

Comparative Example 3 432 g (2 mol) of diphenyldihydroxysilane, 83 g
(1.3 moles) of boric acid, 255 g of 10 centistokes dimethylpolysiloxane silicone oil in a flask and stir in a nitrogen atmosphere for about 6 hours from room temperature.
The mixture was gradually heated to 400 ° C. and further heated and stirred at 400 ° C. for 1 hour to carry out a polycondensation reaction to obtain a polymer.

10 g of each of the polymers obtained in the above Examples and Comparative Examples was dissolved in 10 ml of ethanol, coated on a stainless steel substrate (SUS430) so that the thickness after firing was 10 μm, and dried. Then, it was baked at 200 ° C. for 10 minutes to obtain an insulating film.

The obtained insulating film was evaluated for flexibility, heat resistance, stickiness, moisture resistance and heat loss as follows.

Flexibility The coating obtained above was evaluated by a bending resistance test according to JIS K5400.

Heat resistance The coating obtained above was further baked at 400 ° C. for 1 hour, and the occurrence of cracks in the coating was visually evaluated. ○: No crack occurred, ×: Crack occurred
Indicated by

The coating obtained above was examined for any stickiness by touching it. The case where stickiness was not felt is indicated by ○, and the case where stickiness was felt is indicated by ×.

Moisture resistance The coating obtained above was immersed in water for 10 minutes, and then left standing for one day. Then, the appearance was visually observed to evaluate whether or not devitrification had occurred. The case where no devitrification was observed is indicated by ○, the case where devitrification is slightly observed is indicated by Δ, and the case where devitrification is clearly observed is indicated by ×

Heat loss 10 mg of a polyborosiloxane sample was placed in a platinum pan,
The temperature was raised from room temperature to 400 ° C. at a rate of ° C./min and the reduced weight was expressed as a percentage of the original sample weight (thermogravimetric method). Alumina powder was used as a reference.

The results of the above evaluation are shown in Table 1 below together with the number of moles of silicon compound and boric acid (gram number for silicone oil) used in the production of the polymer.

[0062]

[Table 1] As is evident from the results shown in Table 1, the polyborosiloxane produced by the method of the present invention exhibited flexibility, heat resistance, moisture resistance, stickiness after firing at a low temperature, and loss on heating. However, it is clear that it is significantly superior to that of the comparative example.

[0063]

According to the method for producing a polyborosiloxane of the present invention, it has high flexibility, does not show stickiness when calcined at a relatively low temperature, has little heat loss, and has high heat resistance and moisture resistance. Can be formed.

Claims (5)

[Claims] (1) The following formula (a): (Wherein R represents an alkyl group, an alkenyl group or an aryl group, and X represents an alkoxy group, a hydroxyl group or a halogen atom), and the resulting product is further reacted with a boron compound according to the following formula ( b) Wherein R and X have the same meanings as described above, and a boron compound. 2. The compound of formula (a) and a boron compound are represented by the following formula (c): (Wherein R represents an alkyl group, an alkenyl group or an aryl group). The reaction of the compound of the formula (a) with a boron compound until it is converted into a condensed compound containing an average of 2 to 10 units represented by the following formula: The method of claim 1, wherein: 3. The process according to claim 1, wherein the compound of formula (b) is added to the reaction product of the compound of formula (a) in liquid form with the boron compound. 4. A coating film obtained by applying a coating containing the polyborosiloxane produced by the method according to claim 1 and firing the coating. 5. An inorganic insulated wire having the coating film according to claim 4 as an insulating coating.