Compositions – Preservative agents – Anti-oxidants or chemical change inhibitants
Reexamination Certificate
1999-12-29
2004-05-11
Thexton, Matthew A. (Department: 1714)
Compositions
Preservative agents
Anti-oxidants or chemical change inhibitants
C252S182180, C252S400230, C252S400240, C252S404000
Reexamination Certificate
active
06733693
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to acrylonitrile solutions of maleimides, a method for the preparation thereof, and acrylonitrile based copolymers obtained by the use of the acrylonitrile solutions.
The maleimides represented by N-phenyl maleimide and the like are used as a heat resistance enhancer for such acrylonitrile based copolymers as acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-acrylic rubber-styrene (AAS) resin, acrylonitrile-styrene (AS) resin, and acrylonitrile-chlorinated polyethylene-styrene (ACS) resin.
2 . Description of the Prior Art
The maleimides which are in a solid state at room temperature have been heretofore handled generally in such forms as powder, flakes, and tablets. The maleimides in these solid forms, however, undergo gradual comminution and yield minute particles copiously during the course of transportation and consequently give rise to numerous problems such as deterioration of the work environment. For the solution of these problems, a method for enabling the maleimides to be handled securely in the form of acrylonitrile solutions obtained in advance by dissolving the maleimides together with a polymerization inhibition in acrylonitrile (JP-B-03-12,057) has been proposed. Since this method which permits the maleimides to be handled in the form of acrylonitrile solutions is excellent in having solved the problems mentioned above, it has been finding growing acceptance for industrial applications.
Since the acrylonitrile as the solvent for the acrylonitrile solutions of maleimides constitutes itself the source of the acrylonitrile conpnent of the acrylonitrile based copolymers, the acrylonitrile solutions of maleimides, after being handled as for transportation, are used in their unmodified form for the production of the acrylonitrile based copolymers mentioned above.
The maleimides are yellow and the acrylonitrile solutions obtained by dissolving the maleimides in acrylonitrile are yellow and transparent. So long as the acrylonitrile solutions of maleimides are as yellow and transparent as they were when they were fresh from the production line, the acrylonitrile based copolymers as finished products using the solutions pose no particular problem concerning the color characteristics. In other words, the acrylonitrile based copolymers as the finished products cannot induce such coloration as tends to impair their marketability.
On no occasion, however, the acrylonitrile solutions of maleimides which are fresh from the production line are used immediately for the production of acrylonitrile based copolymers. Generally, the acrylonitrile solutions of maleimides after their production are transported by tank lorries and the like, stored in tanks and the like, or conveyed by the pipeline including pipe, valves, and nozzles (such as, for example, the polymer-feeding line from the storage tank for the acrylonitrile solutions of maleimides) before they are used for the production of acrylonitrile based copolymers. In the present invention, the transportation as by tank lorries, the storage as in tanks, and the conveyance as by the pipeline including pipe, valves, and nozzles (such as, for example, the polymer-feeding line from the storage tank for the acrylonitrile solutions of maleimides) will be referred to collectively as “handling.”
After the acrylonitrile solutions of maleimides have been handled over a specific period, they possibly change color from the inherent yellow color to a brown color, for example, gain in the degree of yellowness (namely, darken the yellow color), or occasionally opacify In this invention, these phenomena will be referred to collectively as “discoloration. ”
The acrylonitrile based copolymers obtained as finished products by using the acrylonitrile solutions of maleimides which have been discolored as described above are colored and have markedly impaired marketability. For the purpose of improving these finished products in marketability, the standards or demands imposed on the color of the acrylonitrile solutions of maleimides have been decisively gaining in exactitude in recent years. In the circumstances, such acrylonitrile solutions of maleimides as are appropriately used for the production of acrylonitrile based copolymers which sparingly incur discoloration due to aging during the course of handling, consequently preclude coloration, and excel in the color characteristics are strongly demanded.
Hereinafter, the acrylonitrile solutions of maleimides will be occasionally referred to simply as “acrylonitrile solutions.”
An object of this invention, therefore, is to provide such acrylonitrile solutions of maleimides as are appropriately used for the production of acrylonitrile based copolymers which preclude coloration and excel in the color characteristics.
Another object of this invention is to provide a method for the production of the acrylonitrile solutions of maleimides mentioned above.
Yet another object of this invention is to provide acrylonitrile based copolymers of excellent color characteristics and high marketability which are obtained by using the acrylonitrile solutions of maleimides mentioned above.
SUMMARY OF THE INVENTION
The objects mentioned above are accomplished by the following aspects (1) to (9) of the present invention.
(1) An acrylonitrile solution of maleimide, characterized by the fact that, in a forced coloration test, the values, &Dgr;L, &Dgr;a, and &Dgr;b, to be calculated in accordance with the following formulas:
&Dgr;L=|L
1
−L
2|(Absolute value)
&Dgr;a=|a
1
−a
1|(Absolute value)
&Dgr;b=|b
1
−b
2|(Absolute value)
wherein L1, a1, and b1 are respectively the values of L, a, and b of the acrylonitrile solution before undergoing the forced coloration test and L2, a2, and b2 are respectively for the values or L, a, and b of the acrylonitrile solution after undergoing the forced coloration test, are respectively not more than 5, not more than 5, and not more than 10.
(2) An acrylonitrile solution of N-phenylmaleimide having azobenzene and N,N-diphenyl hydrazine at a total content of not more than 500 ppm.
(3) A method for the preparation of an acrylonitrile solution set forth in (1) or (2) mentioned above, characterized in that the acrylonitrile solution has a water content of not more than 0.1% by weight.
(4) A method for the preparation of an acrylonitrile solution set forth in (1) or (2) mentioned above, characterized in that the acrylonitrile solution allows the presence therein of at least one member selected from the group consisting of alkyl-substituted hydroxybenzenes and hindered phenols and at least one member selected from the group consisting of phosphorous esters, phosphoric esters, phosphine, and phosphoric acid amides.
(5) A method for the preparation of an acrylonitrile solution set forth in (1) or (2) mentioned above, characterized in that the acrylonitrile solution has a water content adjusted to a level of not more than 0.3% by weight and allows the presence therein of at least one member selected from the group consisting of alkyl-substituted hydroxybenzenes and hindered phenols, phosphorous esters, phosphoric esters, phosphine, and phosphoric acid amides.
(6) A method for the storage of an acrylonitrile solution of maleimide set forth in (1) or (2) mentioned above, characterized in that the molecular oxygen concentration of the gaseous phase portion of the acrylonitrile solution is adjusted to a level in the range of 0.01 to 10% by volume preparatorily to storing the solution as held in contact with a metal.
(7) A method for the preparation of an acrylonitrile solution of maleimide set forth in (1) or (2) mentioned above, comprising the steps of causing a molten maleimide obtained by purifying crude maleimide to allow the presence therein of a primary antioxidant and a secondary antioxidant and subsequently dissolving the solidified maleimide in acrylonitrile.
(8) A method for the preparation of an acrylonitrile solution of mal
Kishino Kazuo
Kita Yuichi
Nakayama Kin-ichi
Shimoyama Fumioki
Mathews, Collins Shepherd & McKay, P.A.
Nippon Shokubai Co. , Ltd.
Thexton Matthew A.
LandOfFree
Acrylonitrile solutions of maleimides, method for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Acrylonitrile solutions of maleimides, method for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Acrylonitrile solutions of maleimides, method for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3253261