Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2000-09-08
2002-03-26
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S918000
Reexamination Certificate
active
06362243
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method for the production of a porous cross-linked polymer which carries out continuously the component steps thereof ranging from a step of supplying a water-in-oil type high internal phase emulsion (hereinafter referred to briefly as “HIPE”) through the step of performing polymerization thereof in the production of the porous cross-linked polymer, preferably a porous cross-linked polymer having continuous cells having communicating pores formed in the surface and the interior thereof (hereinafter referred to also as “open cells”) by the polymerization of HIPE. More particularly, this invention relates to a method for the production of a porous cross-linked polymer which carries out continuously the component steps thereof ranging from a step of supplying the HIPE through a step of polymerizing the HIPE, and can be widely applied to (1) liquid absorbent materials such as, for example, {circle around (1)} core materials in disposable diapers to be used for absorbing water and excrements including urine; and {circle around (2)} agents for disposing of a waste oil and agents for disposing a waste solvent to be used for absorbing oils and organic solvents; (2) energy absorbent materials such as, for example, sound insulating materials and heat insulators in automobiles and buildings to be used for absorbing sound and heat; and (3) chemical impregnating substrates such as, for example, products of toiletry goods impregnated within aromatic agent, a detergent, a lustering agent, a surface protecting agent, and a flame-retarding agent. Further, this invention aims at providing a method for the production of a porous cross-linked polymer which, by selecting the quality of the material for the part destined to be exposed to the HIPE during the course of polymerization, is endowed with a structure having continuous cells (open cells) having communicating pores formed in the surface and the interior of the porous cross-linked polymer, has an improved liquid-passing speed, a liquid-absorbing ratio, and a liquid-absorbing capacity, and is awarded ample freedom in the selection of the composition of HIPE, the device for polymerization, and the conditions of polymerization.
BACKGROUND
Methods for producing a porous cross-linked polymer by polymerizing the HIPE are disclosed in WO-A-97-27240 and WO-A-97-37745, for example.
WO-A-97-27240 discloses as a method for producing a porous cross-linked polymer by the polymerization of the HIPE through the medium of a film a method for the combined continuous-batch polymerization which comprises continuously filling the HIPE in a vertical (perpendicular) ribbon-like zippered bag of resinous film, reeling the filled bag, and polymerizing the HIPE in the bag batchwisely. It further discloses an operation of slicing the porous cross-linked polymer. It also contains a description to the effect that polypropylene (PP) is a preferred material for the film because it is sparingly adhesive to the porous cross-linked polymer, inexpensive, and capable of being recycled.
Then, WO-A-97-37745 discloses a method for producing a porous cross-linked polymer by coating the HIPE on the surface of a porous substrate (such as a felt), allowing at least a part of the HIPE to impregnate the porous substrate, and polymerizing the HIPE lodged in the substrate. It further discloses the necessity for polymerizing the HIPE as held in contact with such a polar material as PET, glass, or water for the purpose of endowing the porous cross-linked polymer with open cells.
Z. Bhumgara (Filtration & Separation, March, 1995, 245-251) describes the fact that in a copolymer of styrene and divinylbenzene, a porous cross-linked polymer with open cells is obtained by using PET, nylon 66, glass, or steel.
The method for polymerizing the HIPE which is disclosed in the official gazette of WO-A-97-27240, however, has the possibility of suffering the bag packed with the HIPE to acquire a larger thickness in the lower part thereof after the elapse of time from the packing operation and yet allowing the uniformity of thickness thereof to be upped to a certain extent by the subsequent reeling operation. Since the product of this method tends to give an increased thickness to the lower part thereof because of the weight of the HIPE itself and, worse still, tends to induce vertical deviation and separation of the oil phase and the liquid phase, it entails problems such as imposing limits on height (width) and thickness, rendering retention of uniformity of thickness, performance, and quality difficult, and permitting no free control of width and thickness. Further, since the operations ranging from packing the bag with the HIPE through polymerizing the packed HIPE cannot be continuously carried out and consequently the successive stages from the continuous step of packaging the bag with the HIPE through the batch step of polymerizing the HIPE in the bag constitute themselves rate-governing processes, the product has the problem of failing to make the most of the advantage of a continuous packing process. Further, since the method uses a bag made of film and, therefore, obtains exclusively a porous cross-linked polymer unique in terms of property, it entails the problem of failing to obtain a porous cross-linked polymer having different properties on the opposite surfaces thereof.
Though the official gazette of WO-A-97-37745 mentioned above has a description to the effect that the polymerization may be carried out by a batch operation or a continuous operation, whichever may fit the occasion better, it has absolutely no specific suggestion as to a method for continuous production of a HIPE using jointly a porous substrate and a polar material.
It is, therefore, an object of this invention to provide a method for the production of a porous cross-linked polymer which allows the produced porous cross-linked polymer to acquire a controlled surface property, permits free control of the width and the thickness of the polymer to be produced, and enables the operations ranging from supplying the HIPE through polymerizing the HIPE to be carried out continuously.
Further, the invention disclosed in the official gazette of WO-97-27240 neither contemplates selecting a film in view of durability at elevated temperature nor takes into due consideration the property fit for cyclic use of the product. The films disclosed by the prior inventions mentioned above use materials of limited quality. Such prior inventions have absolutely no specific suggestion about selecting a film which is excellent in durability fit for polymerization at elevated temperature (such as resistance to heat, resistance to monomer, resistance to hydrolysis, and suitability for cyclic use) and capable of controlling the surface properties (smoothness, capability of forming a texture with open cells, resistance to preclude formation of pinholes, and property of forming voids) of the produced porous cross-linked polymer.
Further, Z. Bhumgara (Filtration & Separation, March, 1995, 245-251) describes that a copolymer of styrene and divinylbenzene, by using PET, nylon 66, glass, or steel, is enabled to produce a porous cross-linked polymer with open cells. The PET is caused as by calcium chloride contained as a constituent component in the HIPE to succumb readily to hydrolysis with an alkaline water-phase component and this trend of the PET is particularly conspicuous when the temperature of polymerization is high. The nylon has a high water absorbing property and shows a phenomenon of swelling and consequently inducing a dimensional variation. The glass is brittle and deficient in heat transfer. The steel forms rust.
The official gazette contains no mention of a material which forms open cells during the copolymerization of a monomer mixture containing an acrylic ester. Neither does it contain any mention of continuous sheet polymerization.
It is another object of this invention, therefore, to provide a method for the production of a porous cross-linked polymer which, by selecting a sheet material contai
Kadonaga Kenji
Minami Kenji
Mitsuhashi Akiko
Nogi Kozo
Sakamoto Katsuhiko
Foelak Morton
Nippon Shokubai Co. , Ltd.
LandOfFree
Method for production of porous cross-linked polymer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for production of porous cross-linked polymer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for production of porous cross-linked polymer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2884962