Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2002-08-23
2004-09-21
Sellers, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C525S453000, C525S504000, C525S523000, C548S240000
Reexamination Certificate
active
06794479
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a one-part epoxy resin composition. More specifically, this invention relates to a moisture-curable epoxy resin composition exhibiting excellent storage stability simultaneously with excellent depth curability; a novel latent curing agent which is capable of imparting a moisture-curable resin composition with sufficient storage stability together with satisfactory depth curability; a moisture-curable epoxy resin composition which exhibits excellent storage stability simultaneously with good curability, and in particular, good surface curability; a moisture-curable epoxy resin composition which has excellent surface curability and depth curability as well as excellent storage stability.
The epoxy resin compositions are most often formulated as a two-part formulation, and in use, the epoxy resin part is mixed with a curing agent and a curing accelerator to promote the curing reaction. However, it is quite troublesome to conduct the mixing immediately before use, and such mixing procedure is often associated with inaccurate measurement or erroneous mixing. In view of such situation, there is a strong demand for a one-part curable epoxy resin composition. A one-part curable epoxy resin composition known in the art is the one using dicyandiamide, imidazole, or the like for the latent curing agent. The compositions of this type, however, required the step of heating for their curing.
Latent moisture-curable curing agents which cure at room temperature are known, and ketimine compounds are typical of such agents.
Various investigations have been conducted on the one-part moisture-curable resin compositions utilizing a latent curing agent, and in particular, those utilizing the ketimine compound. The latent curing agents, however, suffered from the problem of poor storage stability and often underwent gradual viscosity increase or gelation when they were stored in sealed condition after their mixture with the epoxy resin due to high nucleophilicity of the nitrogen atom in imine moiety of the ketimine compound.
Under such circumstances, there have been disclosed various inventions where improvement in the storage stability is sought, for example, use of a ketimine compound having the imine moiety which is sterically hindered to a considerable degree as a latent curing agent which enables improved storage stability. The moisture-curable resin composition using such ketimine compound for the latent curing agent enjoyed good balance between the storage stability and the curing speed. Such composition, however, suffered from insufficient depth curability, and when such composition was used, only a very thin cured film could be formed in a short period.
On the other hand, use of an oxazolidine compound for the latent curing agent of the moisture-curable resin composition was also investigated in order to improve the depth curability of the moisture-curable resin composition. However, use of conventional oxazolidine compound resulted in an insufficient storage stability of the resulting moisture-curable resin composition despite the fairly improved depth curability.
In addition, when an oxazolidine compound is used for the latent curing agent of a one-part epoxy resin composition, the resulting composition suffered from inferior surface curability despite its acceptable depth curability and a period as long as several days was necessary for complete cure of the coated surface.
In view of the situation as described above, an object of the present invention is to solve the problems of the prior art as described above, and to provide:
(1) a moisture-curable epoxy resin composition which is a one-part epoxy resin composition having excellent storage stability simultaneously with excellent depth curability;
(2) a novel latent curing agent which is capable of imparting a moisture-curable resin composition with sufficient storage stability together with satisfactory depth curability;
(3) a one part, room temperature-curable, moisture-curable epoxy resin composition which exhibits excellent storage stability and curability;
(4) a moisture-curable epoxy resin composition which exhibits excellent storage stability simultaneously with excellent depth curability and surface curability.
The epoxy resin compositions of the present invention are not limited for their use as a one-part type, and the epoxy resin compositions may be used as a two-part type by mixing with the curing agent immediately before their use.
More illustratively, the present invention provides an oxazolidine compound represented by formula (1):
wherein
R
1
is methyl group or ethyl group;
R
2
is an alkyl group containing 1 to 6 carbon atoms;
R
3
is methyl group or ethyl group;
R
4
is hydrogen atom, methyl group or ethyl group; and
R
5
is hydrogen atom or a hydrocarbon group containing 1 to 6 carbon atoms;
with the proviso that R
2
, R
3
and R
4
may together represent an alicyclic ring or an aromatic ring; and that R
3
and R
5
may together represent an alicyclic ring or an aromatic ring.
In the formula, R
2
is preferably methyl group.
Also provided is a moisture-curable epoxy resin composition comprising a polyepoxy compound having two or more epoxy groups on average in the molecule, and the oxazolidine compound of the present invention represented by the formula (1).
The moisture-curable epoxy resin composition may further comprise a ketimine compound synthesized from a ketone or an aldehyde represented by formula (2):
wherein
R
6
is hydrogen atom or methyl group;
R
7
is an alkyl group containing 1 to 6 carbon atoms;
R
8
is methyl group or ethyl group; and
R
9
is hydrogen atom, methyl group or ethyl group;
with the proviso that R
7
, R
8
and R
9
may together represent an alicyclic ring or an aromatic ring; and that R
6
and R
7
may together represent an alicyclic ring or an aromatic ring; and
a polyamine.
The backbone of the polyepoxy compound may preferably contain up to 10% by mole of hydroxyl group. It should also be construed that the case wherein no hydroxyl group is included in the backbone of the polyepoxy compound is also within the scope of the invention.
The present invention also provides a latent curing agent containing the oxazolidine compound of the present invention represented by the formula (1), or containing the oxazolidine compound and the ketimine compound as described above.
The present invention also provides a moisture-curable epoxy resin composition comprising a polyepoxy compound having at least two epoxy groups on average in the molecule; an oxazolidine compound and/or ketimine compound; and a silyl phosphate ester and/or acidic phosphoric acid.
The present invention also provides a moisture-curable epoxy resin composition comprising a polyepoxy compound having at least two epoxy groups in the molecule; and an oxazolidine compound represented by formula (16):
wherein
R
17
is a hydrocarbon group containing 1 to 6 carbon atoms; and
R
18
and R
19
either independently represent hydrogen atom or a hydrocarbon group containing 1 to 15 carbon atoms, or together represent an alicyclic ring or an aromatic ring.
R
17
is preferably methyl group or ethyl group.
The first positioned carbon atom of R
18
is preferably a branched carbon or a ring member carbon.
The present invention also provides a moisture-curable epoxy resin composition further comprising a ketimine compound.
The carbon atom and/or the nitrogen atom in the ketimine bond (C═N) of the ketimine compound may preferably have tertiary or quaternary carbon at its &agr; position.
PREFERRED EMBODIMENTS OF THE INVENTION
Next, the present invention is described in further detail.
The present invention is directed to an oxazolidine compound, and a variety of moisture-curable epoxy resin compositions which contain an oxazolidine compound as their latent curing agent for the polyepoxy compound. Included in the present invention are the first to fifth aspects of the invention as described below.
First aspect: an oxazolidine compound represented by the formula (1).
Second aspect: a moistur
Ishikawa Kazunori
Okuhira Hiroyuki
Rader Fishman & Grauer
Sellers Robert
The Yokohama Rubber CO, LTD
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