Aminated polysilazane and process for the preparation thereof

Details Aminated polysilazane and process for the preparation thereof Aminated polysilazane and process for the preparation thereof

2000-02-07

2001-10-30

Dawson, Robert (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From silicon reactant having at least one...

C528S029000, C528S031000, C528S033000, C528S038000, C524S858000, C524S869000, C524S588000, C556S412000, C556S413000, C525S474000

Reexamination Certificate

active

06310168

ABSTRACT:

TECHNICAL FIELD
This invention relates to an amine residue-containing polysilazane and a method of preparing same.
BACKGROUND ART
A polysilazane, when heated, is converted into silica or a siliceous substance (hereinafter simply referred to as SiO
2
substances).
The SiO
2
substances thus formed have excellent insulating properties and are utilized in the electric and electronic fields as an insulating film.
Known polysilazanes, however, have a drawback because, without being modified, conversion rate thereof to SiO
2
substances is low and because a high calcination temperature is required for the conversion thereof into SiO
2
substances.
To solve the above problems, such a proposal has been made that a polysilazane is reacted with a reactive compound as a modifying agent to form a modified polysilazane.
JP-A-H6-128529 proposes a modified polysilazane obtained by reacting a polysilazane with an alkanolamine represented by the general formula: NH
n
(ROH)
3−n
(where R is an alkyl group and n is an integer of 0-2).
In the case of this modified polysilazane, however, it is necessary that a polysilazane be reacted with an aminoalcohol in the form of a methanol or ethanol solution, because of strong hydrophilicity of the aminoalcohol. On the other hand, methanol and ethanol are highly reactive with polysilazanes and can easily decompose the polysilazanes. Therefore, an addition of a large amount of an alcohol to a polysilazane causes problems that the siliceous substance films obtained by calcination of the polysilazane films have a reduced density.
It is an objective problem of the present invention to provide a method of modifying a polysilazane with an amine residue-containing hydroxyl compound without using a lower alcohol such as methanol or ethanol and an amine residue-containing polysilazane obtained by such a method.
DISCLOSURE OF THE INVENTION
According to the present invention, there is provided an amine residue-containing polysilazane having a number average molecular weight of 100-100,000 and having a molecular chain containing a silazane structure represented by the general formula (I) shown below and/or a silazane structure represented by the general formula (II) shown below:
wherein R
1
and R
2
each stand for hydrogen, a hydrocarbyl group or a hydrocarbyl group-containing silyl group, A stands for a divalent hydrocarbyl group, B stands for an N-hydrocarbyl group-substituted amine residue or a cyclic amine residue and p is 0 or 1 with the proviso that p is 1 when B is an N-hydrocarbyl group-substituted amine residue and that p is 0 when B is a cyclic amine residue,
wherein R
1
and R
2
each stand for hydrogen, a hydrocarbyl group or a hydrocarbyl group-containing silyl group, A and A
2
each stand for a divalent hydrocarbyl group, B
2
stands for a divalent linear amine residue or a divalent cyclic amine residue and r and q are each 0 or 1 with the proviso that r and q are each 1 when B
2
is a divalent linear amine residue and that r and q are each 1 or 0 when B is a divalent cyclic amine residue.
The present invention also provides a process for the preparation of an amine residue-containing polysilazane having a number average molecular weight of 100-100,000 and having a molecular chain containing a silazane structure represented by the general formula (I) shown below:
wherein R
1
and R
2
each stand for hydrogen, a hydrocarbyl group or a hydrocarbyl group-containing silyl group, A stands for a divalent hydrocarbyl group, B stands for an N-hydrocarbyl group-substituted amine residue or a cyclic amine residue and p is 0 or 1 with the proviso that p is 1 when B is an N-hydrocarbyl groupsubstituted amine residue and that p is 0 when B is a cyclic amine residue, comprising reacting a polysilazane having a molecular chain containing a silazane structure represented by the general formula (III) shown below:
wherein R
1
, R
2
and R
3
each stand for hydrogen, a hydrocarbyl group or a hydrocarbyl group-containing silyl group, with the proviso that at least one of R
1
and R
3
represents hydrogen, with an amine residue-containing monohydroxyl compound represented by the general formula (IV) shown below:
HO—(A)
p
—B  (IV)
wherein A, B and p have the same meaning as above, in an inert organic solvent having no active hydrogen.
The present invention further provides a process for the preparation of an amine residue-containing polysilazane having a number average molecular weight of 100-100,000 and having a molecular chain containing a silazane structure represented by the general formula (II) shown below:
wherein R
1
and R
2
each stand for hydrogen, a hydrocarbyl group or a hydrocarbyl group-containing silyl group, A and A
2
each stand for a divalent hydrocarbyl group, B
2
stands for a divalent linear amine residue or a divalent cyclic amine residue and r and q are each 0 or 1 with the proviso that r and q are each 1 when B
2
is a divalent linear amine residue and that r and q are each 1 or 0 when B
2
is a divalent cyclic amine residue,
comprising reacting a polysilazane having a molecular chain containing a silazane structure represented by the general formula (III) shown below:
wherein R
1
, R
2
and R
3
each stand for hydrogen, a hydrocarbyl group or a hydrocarbyl group-containing silyl group, with the proviso that at least one of R
1
and R
3
represents hydrogen, with an amine residue-containing dihydroxyl compound represented by the general formula (V) shown below:
HO—(A)
r
—B
2
—(A
2
)
q
—OH  (V)
wherein A, A
2
B
2
, r and q have the same meaning as above,
in an inert organic solvent having no active hydrogen.
The polysilazane used as a reaction raw material in the present invention is known per se and contains in its molecular chain a silazane structure represented by the above general formula (III). In the general formula (III), R
1
, R
2
, and R
3
each stand for hydrogen, a hydrocarbyl group or a hydrocarbyl group-containing silyl group, with the proviso that at least one of R
1
and R
3
represents hydrogen. The hydrocarbyl group includes an aliphatic hydrocarbyl group and an aromatic hydrocarbyl group. The aliphatic hydrocarbyl group in turn includes linear and cyclic hydrocarbyl groups. Examples of the hydrocarbyl groups include an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group and an arylalkyl group. The number of the carbon atoms of the hydrocarbyl group is not specifically limited but may be generally 20 or less, preferably 10 or less. Especially preferred is an alkyl group having 1-6 carbon atoms, more preferably 1-2. In the hydrocarbyl groupcontaining silyl group, the hydrocarbyl group preferably has 1-10 carbon atoms and, more preferably, is an alkyl group having 1-6 carbon atoms. The number of the hydrocarbyl groups bonded to Si is 1-3.
The polysilazane used for the purpose of the present invention may possess a linear, cyclic or crosslinked structure. A mixture of these polysilazanes may also be used. Further the polysilazane used for the purpose of the present invention may be a non-modified polysilazane or a polysilazane modified with a modifying agent such as an organic acid, an isocyanate, an amine, a palladium compound or a platinum compound. The number average molecular weight of the polysilazane is 100-100,000, preferably 300-5,000.
The modifying agent used in the present invention is an amine residue-containing hydroxyl compound of the above formula (IV) or (V).
In the amine residue-containing monohydroxyl compound of the above formula (IV), A stands for a divalent hydrocarbyl group, B stands for an N-hydrocarbyl group-substituted amine residue or a cyclic amine residue and p is 0 or 1 with the proviso that p is 1 or 0 when B is a cyclic amine residue.
The divalent hydrocarbyl group A includes a divalent aliphatic hydrocarbyl group and a divalent aromatic hydrocarbyl group. The divalent aliphatic hydrocarbyl group in turn includes linear and cyclic hydrocarbyl groups. Examples of the divalent hydrocarbyl groups include an alkylene group, an alkenylene group,

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