Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-05-05
2001-12-25
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S125000, C528S126000, C528S128000, C528S172000, C528S173000, C528S179000, C528S183000, C528S188000, C528S220000, C528S229000
Reexamination Certificate
active
06333392
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to novel thermosetting amic acid microfine particles, thermosetting imide microfine particles, thermoset (crosslinked) imide microfine particles, and processes for their production.
BACKGROUND OF THE INVENTION
Imides inclusive of polyimides have good heat resistance, resistance to chemicals, and electric insulating properties in addition to favorable mechanical characteristics so that they have been used not only as electric/electronic materials and automotive materials but also broadly as substitutes for metals and ceramics.
While polyimides are classified by skeletal chain morphology into linear polyimides (thermoplastic type) and three-dimensional network polyimides (thermosetting type), the latter thermosetting polyimides are particularly superior in heat resistance, processability, moldability, etc. and, therefore, are generally acknowledged to be of great use as electrical laminate materials, aerospace materials, and various other molding materials.
As regards the thermosetting imide resin, many versions are known, such as the resin produced by a process starting with a bismaleimide and a diamine compound, as represented by KERIMID (trademark, manufactured by Rhone-Poulenc), and the terminal double bond-containing resin such as the adduct type imide resin represented by the PMR series resin (PMR-11, trademark, manufactured by NASA).
The thermosetting imide resin has been produced typically by the method which comprises reacting a tetracarboxylic dianhydride and an acid anhydride having a carbon-carbon double bond with an organic diamine compound in an organic solvent generally at a temperature of 0~100° C. to prepare a thermosetting amic acid solution, pouring this solution in a nonsolvent for the thermosetting amic acid, recovering the resulting precipitate, and subjecting it to cyclization for imidation.
However, when thermosetting imide resin microfine powders are to be produced from a thermosetting amic acid solution as in the above method, the resin block recovered following said imidation reaction must be pulverized by mechanical means, which adds to the complexity of the process. Moreover, a procedure by mechanical pulverization yields only coarse particles so that a monodispersed system of fine discrete particles can hardly be obtained. In addition, by the above production technology, the shape and size distribution of particles can hardly be controlled. For these reasons, there has been a persistent demand for the development of a technology for producing microfine particles of a thermosetting imide with good monodispersibility and other favorable characteristics.
An object of the present invention, therefore, is to provide thermosetting amic acid microfine particles, thermosetting imide microfine particles and crosslinked imide microfine particles each well-controlled in shape and size distribution.
SUMMARY OF THE INVENTION
In view of the above problems with the prior art, the inventors of the present invention made intensive investigations. As a result, they found that the above object can be accomplished by a technology involving the specific steps disclosed herein and have accordingly completed the present invention.
The present invention, therefore, is directed to a technology for producing thermosetting amic acid microfine particles, thermosetting imide microfine particles and crosslinked imide microfine particles, which has the characteristics set forth below.
1. A method of producing thermosetting amic acid microfine particles starting with a tetracarboxylic anhydride, a carbon-carbon double bond-containing acid anhydride and a diamine compound to synthesize a thermosetting amidic acid, which comprises
(a) a first step of preparing a first solution containing said tetracarboxylic anhydride and said carbon-carbon double bond-containing acid anhydride and a second solution containing said diamine compound and
(b) a second step of mixing said first solution with said second solution and precipitating thermosetting amic acid microfine particles from the mixture (the first invention).
2. A method of producing thermosetting imide microfine particles starting with a tetracarboxylic anhydride, a carbon-carbon double bond-containing acid anhydride and a diamine compound to synthesize a thermosetting imide, which comprises
(a) a first step of preparing a first solution containing said tetracarboxylic anhydride and said carbon-carbon double bond-containing acid anhydride and a second solution containing said diamine compound,
(b) a second step of mixing said first solution with said second solution and precipitating thermosetting amic acid microfine particles from the mixture, and
(c) a third step of imidating the resulting amic acid microfine particles to provide thermosetting imide microfine particles (the second invention).
3. A method of producing crosslinked imide microfine particles starting with a tetracarboxylic anhydride, a carbon-carbon double bond-containing acid anhydride and a diamine compound, which comprises
(a) a first step of preparing a first solution containing said tetracarboxylic anhydride and carbon-carbon double bond-containing acid anhydride and a second solution containing said diamine compound,
(b) a second step of mixing said first solution with said second solution and precipitating thermosetting amic acid microfine particles from the mixture,
(c) a third step of imidating the resulting thermosetting amic acid microfine particles to provide thermosetting imide microfine particles, and
(d) a fourth step of heat-treating the resulting thermosetting imide microfine particles (the third invention).
The present invention is further directed to the following thermosetting amic acid microfine particles, thermosetting imide microfine particles and crosslinked imide microfine particles.
4. Thermosetting amic acid microfine particles having a mean particle diameter of 0.03~1 &mgr;m with a coefficient of variation within the range of 3~15% as obtained by the above method according to the first invention.
5. Thermosetting imide microfine particles having a mean particle diameter of 0.03~1 &mgr;m with a coefficient of variation within the range of 3~15% as obtained by the above method according to the second invention.
6. Crosslinked imide microfine particles having a mean particle diameter of 0.03~1 &mgr;m with a coefficient of variation within the range of 3~15% as obtained by the above method according to the third invention.
DETAILED DESCRIPTION OF THE INVENTION
In the production technology of the present invention, the first step of the second invention and that of the third invention are both identical to the first step of the first invention. The second step of the second invention and that of the third invention are also identical to the second step of the first invention. The third step of the third invention is identical to the third step of the second invention. The respective steps are now described in detail.
(1) The First Step
In preparing thermosetting amic acid microfine particles in accordance with the present invention, a first solution containing a tetracarboxylic anhydride and a carbon-carbon double bond (C═C bond)-containing acid anhydride and a second solution containing a diamine compound are respectively prepared in the first place. In carrying the present invention into practice, it is particularly advisable that the tetracarboxylic anhydride and C═C carbon-containing acid anhydride on one hand and the diamine compound on the other hand are prepared as independent solutions.
The First Solution
The tetracarboxylic anhydride is not particularly restricted but any compound heretofore used in imide (polyimide) synthesis can be employed. Thus, the tetracarboxylic anhydride which can be used includes aromatic tetracarboxylic anhydrides such as 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,3,3′,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride (PMDA), 1,3-bis(2,3-dic
Asao Katsuya
Saito Hidenori
Hampton-Hightower P.
Smith , Gambrell & Russell, LLP
Sumitomo Bakelite and Co. Ltd.
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