An image receiving layer comprising an ink receptive crosslinked polymer comprising the reaction product of a multifunctional aziridine crosslinking agent and a polymer containing protonated pyridine substituents. Image receiving layers may also contain at least one swellable polymer and additives such as particulates, mordants, fillers and the like.

The invention relates to image receptor sheets that may be stacked without image offset and more particularly to crosslinkable coating compositions applied to film and paper substrates to provide absorbent, ink receiving layers bearing images of high fidelity and color saturation. Image bearing sheets are durable and scuff resistant in the presence or absence of water.
The presentation of pictorial and textual images requires materials, as image receptors, that retain evidence of the color, tone, resolution and brightness of the original pictorial subject or textual message. Certain characteristics are required of image receptor materials to provide suitable contrast and fidelity of image reproduction. This need applies particularly to receptors used for recording images formed from colored droplets such as those delivered by ink jet printers and copiers. An image recorded as liquid droplets requires a receptor on which the recording liquid dries quickly without running or spreading. High quality image reproduction using ink jet printing techniques requires receptor substrates, typically sheets of paper or opaque or transparent film, that readily absorb ink droplets while preventing droplet diffusion or migration. Ready absorption of ink encourages image drying while minimizing image migration maintains the sharpness of the appearance of the recorded image.
Advances in ink jet printing technology yielded ink jet printers requiring less time for complete image generation. Improvements in printer technology translate into the need for improved receptor materials that satisfy a number of important requirements related to increasing speeds of multicolor printers. In addition to the need for image sharpness and rapid absorption of ink droplets, there is a demand for image receptors that satisfy quality standards with respect to brightness, opacity, internal strength, and resistance to picking and scuffing. An effective receptor material also protects an image from water damage that would extract color from an image or distort its appearance by image bleeding due to spreading of an area of colored dye.
Solutions to problems associated with the use of aqueous ink jet inks include the use of water swellable polymers, and hydrophilic additives to improve liquid absorption and drying rate. The use of mordants provides control of liquid droplets, as deposited, to enhance image sharpness and limit droplet migration that appears as image bleeding.
Despite improvement in the performance of ink jet image receptors a challenge exists to provide sheet materials so that multiple imaged sheets may be stacked in the output tray of ink jet color printers, without evidence of image transfer between sheets in the stack. Such image transfer is also known as image offset or blocking.
Receptor sheet durability is an issue related to the preservation of recorded images which may be damaged by picking and scuffing. Picking and scuffing could occur during stacking of multiple sheets during high speed printing or copying. Therefore, increased durability may allow stacking of imaged sheets with less blocking, in less time. This is becoming important in response to the increasing image generation speed of ink jet printers.
It is known that introducing crosslink sites into a polymer structure may increase its toughness and durability. The benefits of durability of crosslinked polymers may be applied to image receptor layers. In the case of ink jet imaging, coatings for receptor layers typically comprise water soluble polymers that upon crosslinking become less water soluble with reduced tack and increased durability, especially in imaged areas that are saturated with aqueous-based ink.
A known crosslinking reaction that may be applied to image receptor layers involves the interaction of carboxy terminated materials and multifunctional aziridines. Information of crosslinking of carboxylate species using multifunctional aziridines is available in a number of references exemplified by United States Patents including U.S. Pat. No. 3,470,136; U.S. Pat. No. 3,507,837; U.S. Pat. No. 3,817,945; and U.S. Pat. No. 3,959,228. Further evidence of the use of multifunctional aziridine crosslinking agents with carboxylic acid groups is given in U.S. Pat. No. 4,490,505. This patent teaches the benefit of reacting aziridines with carboxylic acid groups rather than other types of groups, such as primary and secondary amine groups, hydroxyl groups and phenolic groups, which react more slowly with the crosslinking agent.
U.S. Pat. No. 5,208,092 describes the use of multifunctional aziridine crosslinkers for carboxylic acid groups in liquid ink-receptive recording sheets. The crosslinking reaction in this case involves compositions containing from 0.5% to about 20% by weight of at least one ethylenically unsaturated monomer having acidic groups in ammonium salt form. Such groups react to form crosslinks in the presence of a multifunctional aziridine, present from 0.5% to about 8.0% by weight. Illustration is provided of a crosslinking scheme. U.S. Pat. No. 5,389,723 also describes ink receptive layers crosslinkable through reaction of acid groups with polyfunctional aziridines such as propane-tris(xcex2-(N-aziridinyl)propionate. The ink receptive layers may contain pendant ester groups, and these can be rendered crosslinkable by hydrolysis.
As indicated, known crosslinking reactions involving multifunctional aziridine crosslinkers appear to emphasize the benefits of the ready reaction of such crosslinkers with carboxylic acid functionality. Reference to the relative slowness of reactions involving other functional groups suggests the potential inferiority of the crosslinked structures they produce. It could also be inferred that accelerating such reactions, e.g. using more vigorous high temperature conditions, may adversely affect performance properties of the resulting product.
Crosslinked systems derived from carboxylic acid group reaction with multifunctional aziridines have produced useful ink receptor materials. Although apparently less reactive, the possibility exists that other crosslinkable compositions may provide ink receptors having similar or improved properties compared to those operating through the reactivity of carboxylic acid functionality. For this reason there is a need to explore other crosslinking schemes involving multifunctional aziridine crosslinkers as well as their application to image recording products.
The present invention provides a coated receptor for images formed from droplets of colorants issuing from discharge elements of image reproducing equipment, such as the nozzles of ink jet printers. A coated receptor, according to the present invention, includes an ink receptive layer comprising up to 80% of a homopolymer of a protonated polyvinylpyridine to provide crosslinked polymer networks by reaction with multifunctional aziridines. As an alternative the polymer requirement for an ink receptive layer may be satisfied using a copolymer including protonated pyridinium substituents. The ink receptive layers comprising pyridine-containing homopolymers or copolymers exhibit improved performance with respect to durability, scuff resistance, and image fidelity. They also exhibit water and moisture stability and limit migration that leads to image bleeding. The use of pigmented inks, applied to receptor layers according to the present invention, typically produces images of higher density with less xe2x80x9cmud cracking.xe2x80x9d Coating compositions, used for ink receptive layers possess improved stability for extended periods of time, compared with previously known, carboxylic acid-containing, polymer structures crosslinked using multifunctional aziridines. Receptor layer compositions according to the present invention dry efficiently, after coating, at temperatures that minimize damage to substrate materials including paper and film substrates.
Preparation of a durable receptor layer according to the present invention relies upon a crosslinked polymer network that may be accomplished in at least two ways. In one embodiment of the invention, the structure of a pyridine-containing polymer, that crosslinks via reaction with a multifunctional aziridine, may contain the maximum number of pyridine substituents using a vinyl pyridine homopolymer. High incidence of pyridine groups increases the probability of high crosslink density during reaction with aziridine crosslinkers. Alternatively, a copolymer of vinyl pyridine, containing fewer pyridine groups will result in a lower level of crosslinking depending upon the amount of vinyl pyridine constituent in the copolymer. Anticipating that the durability of a receptor layer will increase with increased crosslinking, adjustment of proportions of vinyl pyridine to other monomers in a copolymer should allow adjustment of receptor layer durability. Due to the dependence of durability on the concentration of pyridine substituents, effective performance of receptor layers in terms of abrasion resistance and scuff resistance is not particularly dependent upon the selection of other monomers, used to form copolymers with vinylpyridine. A wide variety of copolymers may be used providing they include from about 2% to about 95%, preferably about 15% to about 45% pyridine substituents.
Another approach to varying the crosslink density of polymers and copolymers produced using vinyl pyridine involves the protonation of either all or only a portion of available pyridine substituents. Protonation results from the acidification of pyridine containing polymers and copolymers. Acid treatment of such polymers converts pyridine nuclei to positively charged pyridinium substituents suitable for reaction with multifunctional aziridine crosslinkers. Fully protonated polymers provide more highly crosslinked polymer networks than partially protonated polymers based on the same polymer structure. Durability of receptor layers may be varied, therefore, by changing the amount of vinyl pyridine included in a polymer backbone or adjusting the amount of protonating acid. The facility for adjusting the durability of crosslinked polymers also leads to the preparation of self-supporting image receptor layers that may be formed into sheet and film structures without need for a supporting substrate.
Another benefit of protonation is the formation of an internal mordant in receptor layers according to the present invention. The pyridinium groups produced by acidification of pyridine containing polymers also provide charge centers that are beneficial for reducing dye diffusion that leads to bleeding. This added advantage reduces or eliminates dependency on known mordant compounds that may be added to receptor layer compositions according to the present invention.
The previous discussion shows the multiple advantages of receptor layers comprising vinyl pyridine homopolymers and copolymers. Incorporation of such polymers provides variable durability in terms of layer integrity and resistance to rubbing, scuffing and related abrasion. Durability depends on crosslink density developed using multifunctional aziridine crosslinkers that act as catalysts rather than initiators. The catalytic reaction requires polymer protonation with production of pyridinium ions. Pyridinium ions impart mordant capacity to receptor layers according to the present invention. Pyridine containing polymers provide the dual function of crosslinking site and mordant to improve the performance of ink jet image receptors.
More particularly the present invention provides an image receiving layer comprising and ink receptive crosslinked polymer comprising the reaction product of a multifunctional aziridine crosslinking agent and a polymer containing protonated pyridine substituents. Image receiving layers may also contain at least one swellable polymer selected from the group consisting of polyvinyl alcohol, hydroxypropylmethyl cellulose, polyvinylpyrrolidone, hydroxyethylcellulose, hydroxypropylcellulose, polyacrylamide, polyethylene oxide, gelatins, starches, and copolymers and blends thereof. Additional benefits may be derived by inclusion of particulates, mordants, fillers and the like.
Definitions
Terms used herein have the meaning indicated in the following definitions.
The terms xe2x80x9creceptor layerxe2x80x9d or xe2x80x9cimage receiving layerxe2x80x9d refer to a cured composition that is suitably self supporting to absorb droplets of aqueous-based ink without deteriorating.
A xe2x80x9creceptor sheetxe2x80x9d includes a receptor layer coated on a substrate to provide added support to the receptor layer. A substrate may be in the form of a paper product or an opaque or transparent resin or polymer film.
The term xe2x80x9cink absorptionxe2x80x9d or xe2x80x9cliquid absorptionxe2x80x9d refers to the affinity of a receptor layer for aqueous-based inks and related colored liquids so as to attract them into the body of the layer and away from the surface, thus promoting surface drying.
xe2x80x9cAqueous-based inkxe2x80x9d refers to ink composed of an aqueous carrier and a colorant such as a dye or pigment dispersion. An aqueous carrier may contain water or a mixture of water and a solvent.
The term xe2x80x9cwater stabilityxe2x80x9d refers to the capacity of a receptor layer to remain intact in contact with water, during water soaking or application of water as a continuous stream.
xe2x80x9cA swellable polymerxe2x80x9d is an ink or liquid absorbing material that increases in volume during contact with aqueous-based inks thereby increasing its liquid uptake rate and holding capacity.
The term xe2x80x9cdurabilityxe2x80x9d refers to that property of a receptor layer that protects it from impact, rubbing and scuffing to preserve the integrity of the receptor layer both before and after the deposit of an image of liquid droplets. Receptor layer durability herein accrues from the provision of a crosslinked structure within the layer.
xe2x80x9cA mordantxe2x80x9d is a material that interacts with the dyes contained in inks to decrease or prevent their diffusion through the media. Diffusion of dyes, after imaging, results in the spreading of colors from one area to another, often seen as apparent broadening of fine lines during image storage.
The term xe2x80x9cbleedingxe2x80x9d refers to previously described diffusion of dyes through the media after imaging. Diffusion adversely affects image appearance due to deterioration in the resolution and sharpness of pictorial elements. Bleeding may be lessened or prevented by the use of mordant compounds.
A xe2x80x9cfunctional materialxe2x80x9d herein refers to a material included in a receptor layer to enhance or improve properties associated with recording, retaining and displaying of images, particularly ink jet printed images.
The term xe2x80x9coptional materialxe2x80x9d refers to a material included in a receptor layer to improve non-image properties, such as handling and feeding or receptor sheets according to the present invention.
xe2x80x9cImage offset or blockingxe2x80x9d refers to the indiscriminate transfer of liquid ink by contact with other surfaces and objects when an image of ink droplets remains wet too long on the surface of a receptor layer. The same term may be used to describe transfer, between surfaces, of portions of a receptor layer due to lack of internal cohesion of the layer or lack of adhesion to the substrate of an receptor sheet. Such transfer is detrimental to the stacking of multiple receptor sheets since a wet image or fragile receptor layer will tend to transfer to the backside of the next receptor sheet ejected into the output tray of a high speed ink jet printer.
The term xe2x80x9c(meth)acrylatexe2x80x9d indicates the use of either and acrylate ester or a methacrylate ester.
xe2x80x9cMud crackingxe2x80x9d refers to micro-cracking apparent within imaged areas of receptor layers printed with pigmented inks. Micro-cracking adversely affects image quality.
The terms xe2x80x9cpyridine substituentxe2x80x9d or xe2x80x9cpyridine contentxe2x80x9d refer to pendent groups included in a polymeric structure and the concentration of such groups in a polymer.
xe2x80x9cProtonationxe2x80x9d refers to the addition of a hydrogen ion to a pyridine substituent to produce a positively charged pyridinium ion attached to a polymeric structure.
Having described improvement in durability and internal mordant capacity the enhancements and benefits provided by receptor layers are described in greater detail hereinbelow with respect to several alternative embodiments of the present invention.
The present invention provides receptor layers for images produced during the operation of computer controlled ink jet printers. After application to selected substrates, preferably in the form of sheet materials including paper, and opaque and transparent films, receptor layers preserve desirable appearance characteristics of sharpness without bleeding for images produced by ink jet printers. These characteristics result from properties of the receptor layers that encourage rapid liquid ink absorption yet limit diffusion of ink droplets within the layer. Rapid liquid absorption draws ink away from the surface of a receptor layer to reduce surface spreading or puddling of liquid inks. Removal of surface liquid from imaged sheets produces printed output that is less susceptible to ink transfer between sheets. This, combined with crosslinking, also results in less blocking, during stacking of images from high speed printers. During stacking of imaged sheets, sliding contact occurs between individual sheets as they are delivered to a printer""s output tray. Sliding contact may cause surface scuffing as imaged sheets rub together. Image offset also occurs during such contact unless receptor layers possess properties that lead to rapid surface drying and durability.
A distinguishing feature of the present invention is the provision of receptor layers with scuff resistance and increased durability. Resistance to scuffing is possible by the addition of a crosslinking component to receptor layer compositions according to the present invention. There are few suitable crosslinking systems for use in receptor layers for ink jet images. The crosslinking reaction typically occurs under relatively mild drying conditions as needed to prevent damage to thermally sensitive receptor layer bearing substrates, particularly photopaper backings and transparent backings such as polyester films. Also, maintenance of receptor performance requires a substantially irreversible crosslinking reaction. Preferably the reaction occurs at oven temperatures and dwell times that substantially prevent discoloration or damage either to a substrate or to a receptor layer. It will be appreciated that any discoloration of either a receptor layer or a receptor sheet can be detrimental to the appearance of a printed image. Reference to receptor sheet damage may be appreciated considering the types of surface imperfection produced by many polyethylene coated papers that typically blister if heated above 145xc2x0 C. (290xc2x0 F.) for longer than 2 minutes.
Crosslinking with multifunctional aziridines is one of a few reactions suitable for use with ink jet image receptor layers. As discussed previously, the crosslinking of polymers containing carboxylic acid functionality with multifunctional aziridines represented one of the few practical approaches for increasing the durability of ink jet receptor layers during the process of manufacturing.
The reaction of multifunctional aziridine crosslinking agents with protonated pyridine functionality, instead of carboxylate functionality offers durable receptor layers that in addition possess the properties of a mordant. Also, this crosslinking system provides water resistant receptor layers retaining images that lose relatively little density when soaked in water. They also show extremely good high humidity bleed performance.
Preferred compositions use multifunctional aziridine crosslinkers with polymers containing pyridine substituents, more particularly protonated pyridine substituents, resulting from the addition of acid to pyridine containing polymers. This alternative provides improved control of coating and thermal curing of receptor layers according to the present invention. For example, crosslinking reactions between multifunctional aziridines and protonated pyridine moieties tend to be less vigorous than reactions between carboxylic acid groups and multifunctional aziridines. This reduction of reactivity provides benefits regarding the storage stability of receptor layer compositions before coating.
In addition to providing desirable improvement in the durability of ink jet image receptor layers the use of multifunctional aziridine crosslinking with e.g. polyvinylpyridine polymers yields cationic species associated with the polymer. The presence of cationic sites on crosslinked polymers in receptor layers according to the present invention contributes to increased mordanting of dyes and less bleeding of recorded images. This benefit is not obtainable with polymers crosslinked via reaction of multifunctional aziridines and carboxylic acid functionality.
The added benefits of increased durability and mordant capacity of receptor layers containing polyvinylpyridine and related polymers arise from the use of a highly charged cationic polymer before crosslinking with multifunctional aziridines. High levels of cationic species with pyridine-containing systems usually occur under acidic conditions. Similar conditions existing during crosslinking of typical carboxylic acid functional polymers lead to accelerated crosslinking activity and less stability of receptor layer compositions before coating. This makes even more surprising the fact that highly protonated polymers, containing pyridine and related functionality, remain relatively unreactive in solution, in the presence of multifunctional aziridines. Measurement of dissociation tendencies reveals a pKa value of approximately 4.5 for carboxylic acid groups and approximately 5.2 for protonated pyridine. Although protonated pyridine and carboxylic acids differ by less than an order of magnitude in pKa values, there is, as indicated above, a marked difference in the reactivity of the two systems. Both have conjugate bases with the ability to act as nucleophiles in ring opening of multifunctional aziridines during crosslinking, but at different rates. As the pH of the coating solution approaches from about 1 to about 3 there is an increase in the rate at which multifunctional aziridine disappears from solution. Rapid consumption of aziridine crosslinker leads to premature gelling of coating compositions based upon carboxylic acid functionality. In contrast, gel formation does not normally occur with compositions containing protonated pyridine functionality, e.g. highly protonated polyvinylpyridine. This was demonstrated by adding a solution of 20 parts of a 10% aqueous solution of 90% protonated polyvinylpyridine and 3 parts of a 10% ethanol solution of a trifunctional aziridine (XAMA-7, available from Sybron Chemicals Inc., Birmingham, N.J.) to 100 parts of a solution of 8.4 g polyvinylalcohol in 100 g of 90:10 ethanol: water mixture. This provided a coating composition of pH 6 that showed no gelling when first prepared or after a period of at least one-week. Receptor layers of this composition exhibited substantially the same performance regardless of the use of a newly prepared or aged coating composition. Addition of various cationic materials to crosslinkable protonated polyvinylpyridine, in the presence of multifunctional aziridines may enhance the performance of receptor layers. For example, cationic alumina sols can be added up to 50% of the formulation solids. The presence of such materials provides improvement towards elimination of mud cracking in pigmented areas of imaged receptor layers according to the present invention. Incompatibility of cationic sols, of the type described above, with receptor layer coating compositions containing multifunctional aziridines and carboxylate functional components denies the same benefits to these crosslinkable systems.
The receptor layer compositions described previously contain polyvinyl alcohol as a water absorbing, water swelling polymer capable of rapidly drawing liquid into the layer and away from the receptor surface. Polyvinyl alcohol is one of a number of swellable polymers that rapidly absorb liquid into the receptor surface. Others liquid swellable materials suitable for this purpose include homopolymers and copolymers such as hydroxypropylmethylcellulose available as METHOCEL from Dow Chemical Company, Midland, Mich., Polyvinylpyrrolidone, hydroxyethylcellulose available under the tradename NATROSOL from Aqualon Company, Palatine, Ill., hydroxypropylcellulose available under the tradename KLUCEL from Hercules Inc., Wilmington, Del., starches, polyethylene oxide, polyacrylamides, gelatin and the like. The crosslinking reaction of polyvinylpyridine that is effective in the presence of polyvinyl alcohol and similar swellable polymers is also effective with copolymers containing vinylpyridine. This allows further modification of receptor layer properties. Suitable copolymers include those containing vinyl pyridine from about 2.0% to about 95.0%, preferably about 15% to about 45%, with the remaining composition made up of monomers selected from the group consisting of (meth)acrylate esters, where the ester groups may be alkyl, hydroxyalkyl, alkoxyalkyl, haloalkyl, poly(ethylene glycol) and the like, as well as acrylamides, n-vinyl pyrrolidone, styrene, substituted styrenes, vinyl ethers and the like. Properties of crosslinked receptor layers may also be varied by adjusting the amounts of acid added to pyridine containing polymers and copolymers to vary the level of protonation of a crosslinkable polymer. Other materials that are useful in crosslinking compositions according to the present invention include various pyridine salts including pyridinium chloride, sulfate, acetate, trifluoroacetate and the like.
The previous description indicates the need for receptor layers containing polyvinylpyridine to also include a water swellable polymeric component, for rapid absorption of liquid image droplets. A swellable polymer may also be used in receptor layer compositions comprising copolymers having pyridinium substituents such as those formed by reaction of vinylpyridine with other suitable monomer species and materials that react to form a crosslinked component that contributes durability and scuff resistance to the layer. The polymer component of a receptor layer composition may act as a binder for other materials contained in a receptor layer. Other materials may include functional materials that enhance image characteristics, or optional materials to improve, e.g. handling and feeding of coated sheets for optimum performance with printing and copying equipment.
Functional materials that improve image characteristics of receptor layers include plasticizers, surfactants, particulate materials and mordants. Particulate materials may be added to receptor layer compositions in any way that results in thorough dispersion of particles. Addition of particulate material in a pre-dispersed condition, such as the use of sols or emulsions, offers some useful advantages. Receptor layers according to the present invention may comprise particulates including alumina sols and cationic emulsions, and the like. Surprisingly, particulate materials appear to reduce mud cracking associated with the deposit of pigmented inks on receptor layers.
It is known that particulate materials contribute both liquid absorption and mordant properties to receptor layers for ink jet images. As a mordant, a particulate helps to restrict liquid diffusion in a receptor layer to preserve image sharpness. The liquid absorbing capacity of a particulate aids the speed at which a liquid departs from the surface of a receptor layer. This improves the surface-drying rate of image receptor sheets that thereafter exhibit lower incidence of image offset to facilitate more rapid stacking of imaged sheets, as required by the capabilities of current ink jet printers.
The presence of particulate materials and crosslinked polymers containing pyridinium functionality provides mordant capacity to receptor layers according to the present invention. A mordant is a material that interacts with dyes, contained in the inks, to decrease or prevent their diffusion through the media. Image bleeding reduces image resolution causing the loss of detail from the pictorial presentation captured by an image receptor layer. To further reduce bleeding, known effective mordant compounds may optionally be added to receptor layers. Mordant compounds are well known to those having skill in the imaging and photographic arts. A variety of mordants exist as additives satisfying the image quality needs of receptor layers according to the present invention.
Optional components to improve handling and sheet feeding characteristics may include additives including plasticizers, surfactants and fillers. Suitable plasticizers for receptor layers according to the present invention include, for example, PYCAL 94 (available from ICI Surfactants, New Castle, Del.) sorbitol xylitol, glycerol, mannitol, pentaerythritol, polyethylene glycols and trimethylol propane. Surfactants may be added to aid the coating of receptor layers. They include preferably nonionic or cationic surfactants. Non-limiting examples include surfactants such as various fluorinated materials, including ZONYL FSO, ZONYL FSO 100, ZONYL FSN, and ZONYL FS-330 (available from DuPont Specialty Chemicals, Memphis, Tenn.), alkylphenol ethoxylates, for example TRITON X-100, and TRITON X45 (available from Union Carbide, Danbury, Conn.), polyoxyethyleneglycol derivatives, for example TWEENS 60, TWEENS 61, TWEENS 65 and TWEENS 80 (available from ICI Americas, Inc., Bridgewater, N.J.), polydimethylsiloxane derivatives, such as SILWET L-7600, SILWET L-7605, and SILWET L-7607 (available from OSi Group, Tarrytown, N.Y.), and acetylenic derivatives, for example SURFYNOL 465 and SURFYNOL 486 (available from Air Products and Chemicals, Inc., Orlando, Fla.).
Filler additives may include a variety of types of powder such as silica, alumina, clays, starches, polyolefin powder, polystyrene powders and those having a specific particle shape including spherical particles available in the form of polymeric microspheres and bead polymers such as polymethylmethacrylate (PMMA) beads.
Coatings of receptor layer compositions may be applied by any of a number of methods for applying fluid layers of selected thickness to transparent and opaque substrates. Suitable methods include knife coating, wire bar coating, gravure coating, and extrusion coating.
Receptor layers according to the present invention may be self-supporting. The capability of such layers to retain image fidelity within a single layer, even during soaking with water, demonstrates that they may be used independent of other supports. Preferably, however, a substrate provides support to a coated and thermally cured receptor layer to obtain the benefits to image quality provided by suitable substrates.
For this purpose, suitable substrate materials include paper structures including filled papers developed particularly for quality photographic print presentation. Substrate materials also include opaque and transparent film backings such as cellulose triacetate or cellulose diacetate, polyethylene naphthalate, polystyrene, and polyesters, especially polyethylene terephthalate. Preferred substrates have a caliper between about 50 microns to about 200 microns and develop a strong bond to receptor layers according to the present invention.
To promote adhesion between a substrate and a receptor layer it may be necessary to prime the surface of the substrate using one or more primers applied in single or multiple layers. Coated primers preferably have a thickness less than 2.0 microns. Examples of priming materials include halogenated phenols dissolved in organic solvents, polyvinylidene chloride and gelatin subbing agents. As an alternative, priming of substrate materials may be accomplished using physical priming methods including surface treatment by corona and plasma discharge.
The use of receptor layers according to the present invention primarily addresses the needs of imaging processes associated with ink jet printers and copiers. Receptor sheets produced for this purpose may also find use in other types of imaging processes. Among these imaging processes there may be included electrophotographic methods and related methods based upon image formation using a plurality of image elements such as toner powder particles and wax-containing fluid droplets.
Receptor layers and receptor sheets according to the present invention will be described, as follows, in terms of examples and performance characteristics. Such examples are provided for the purpose of illustration without limiting the scope of the invention.
Solution and Dispersion Preparation
Solution A was prepared by dissolving 8.4 g of AIRVOL 540 polyvinyl alcohol in 100 mls of a 90:10 mixture of distilled water and ethanol
Solution B was prepared by treating 5.0 g polyvinylpyridine with 2.5 g glacial acetic acid and adding water to give 50 g of a solution approximately 10% in polyvinyl pyridine, protonated to 90%.
Solution C was prepared by dissolving 10 g of a multifunctional aziridine (XAMA-2) in 90 g of ethanol.
Solution D was prepared by dissolving 7.5 g METHOCEL K35 in 92.5 g of water.
Solution E was a copolymer prepared as a 25% solids solution in a 90:10 mixture of distilled water and ethanol. The copolymer contained ethyl acrylate (EA), hydroxy propyl acrylate (HPA), N-vinylpyrrolidone (NVP), and vinylpyridine (VPy) in the proportions 20:20:30:30.
Solution F was made from 10 g of Solution E to which 0.35 g glacial acetic acid was added, followed by dilution to 25 g with distilled water.
Solution G was a 20% solution of a mordant (DYEFIX 3152 available from Sybron Chemicals, Birmingham, N.J.) in water.
Solution H was a 20% solution of a mordant (VANTOCIL available from Avecia, Wilmington, Del.) in water.
Solution I was a copolymer containing EA/ HPA/NVP/VPy in the proportions 20:40:10:30 at 24.6% solids in a water ethanol mixture, as above.
Solution J was a 20% solids solution of the copolymer neutralized with trifluoroacetic acid, prepared by adding 3.55 g of ethanol and 1.56 g trifluoroacetic acid to 20 g of Solution I.
Solution K was made by dissolving 10 g polyethyleneimine (water-free grade, available from BASF Corporation, Budd Lake, N.J.) in 267 g water, followed by addition of 13.3 g trifluoroacetic acid.
Dispersion I was an alumina sol containing 25% solids in water and available as DISPAL 23N4-20 from Condea Vista, Tucson, Ariz.
Dispersion II was an experimental alumina sol containing 15% solids in water and available as DISPAL 954-25 from Condea Vista, Tucson, Ariz.
Dispersion III was made by dispersing 5 g of polymethylmethacrylate (PMMA) beads, 40 microns in diameter, in 95 g water.
Coating Preparation
Compositions of Examples 1-3 were coated on a primed white microvoided polyethylene terephthalate at a thickness of 175-200 microns (7 mil). The resulting coated sheet was dried at about 130xc2x0 C. to about140xc2x0 C. (265xc2x0 F. to 285xc2x0 F.) for times in the range of 1 minute to 3 minutes to provide a colorless glossy image receptive layer.
Image Formation
Film sheets coated with receptor layers were imaged using a Hewlett Packard 970C ink jet printer operating in HP Premium Plus Photo Paper Glossy mode. This generates a three color process black, versus a monochrome pigmented black image.
TEST RESULTS


A contraceptive and/or HRT (hormone replacement therapy) kit comprising sequential daily dosage units each containing as the sole contraceptively effective ingredient a progestogen, or as the effective ingredient for HRT a progestogen with or without an estrogen or an estrogen only, and further two or more dosage units comprising an anti-progestogen. The present invention also provides contraceptive and HRT methods comprising administering daily dosage units of a progestogen and anti-progestogen.

The invention relates generally to progestogen-anti-progestogen regimens for use in contraception and hormone replacement therapy, and more specifically for contraception to progestogen-anti-progestogen regimens involving only the administration of a progestogen and an anti-progestogen.
It has been known for some time that contraception can be achieved by the oral administration of sufficient quantities of a progestogen to a female of child-bearing age. Contraceptive preparations that minimize the incidence of menstrual spotting, break through bleeding, variations in menstrual cycle length and amenorrhea are preferred. It is further preferred to use contraceptive regimens that minimize the amounts of estrogens and progestogens used. Preparations that fulfill many of these requirements are disclosed in WO 93/21927, wherein a contraceptive regimen free from estrogens is described, the active ingredient being a progestational agent and intermittently an anti-progestogen. The regimen used is a regimen wherein only levonorgestel is administered as the progestogen, except that on days 1, 30, 60, 90, 120, 150, and 180 a dosage of the anti-progestogen RU 486 is administered. In fact the regimen is a progestogen-only regimen, interrupted by anti-progestogen administration at the beginning of each cycle. Although this regimen is a considerable improvement over existing regimens comprising estrogens, the bleeding profile is still not perfect since it recurs slowly after an almost bleeding-free interval, and further improvement is therefor desirable.
xe2x80x9cProgestogen-only pillsxe2x80x9d are a preferred method of contraception for breast-feeding mothers, older women, women for whom estrogen is contraindicated, women who are hypertensive, and women who develop migraine headaches when taking a combined pill (i.e. one containing an estrogen and progestogen component). See, e.g. xe2x80x9cContraception for women over the age of 35xe2x80x9d, IPPF Medical Bulletin, 22: 3-4 (1988) and P. W. Howie xe2x80x9cThe progestogen-only pillxe2x80x9d, Brit. J. Obstet. Gynaecol., 92: 1001-2 (1985). While different progestogen-only regimens have been described, they are still associated with incomplete ovulation inhibition, and relatively high failure rates. Vessey et al xe2x80x9cProgestogen-only oral contraception. Findings in a large prospective study with special reference to effectivenessxe2x80x9d, Brit. J. Family Planning, 292: 526-30 (1986). It has been suggested to increase the daily dosage of progestogen in order to induce complete ovulation inhibition, however such an increase in dosage also increases the frequency of intermenstrual bleeding (i.e. xe2x80x9cspottingxe2x80x9d), which is clearly not desired. E. Diczfalusy et al, Progestogens in Therapy, p. 150 (Raven Press, NY 1983).
Moreover, a high prevalence of functional ovarian cysts have been reported with progestogen-only contraceptive regimens, which resolve after discontinuation of the progestogen-only contraceptive. Fotherby, K. xe2x80x9cThe Progestogen-pillxe2x80x9d, in: Filshie et al eds. Contraception: Science and Practice, pp. 94-108 (1989), and Howie, supra. A need exists for a progestogen-only contraceptive regimen which more effectively inhibits ovulation, while still not increasing the frequency of intermenstrual bleeding, or leading to persistent functional ovarian cysts. The solution to this need by adding intermittently an anti-progestogen needs further elaboration.
Surprisingly, it has now been found that apart from administering an anti-progestagen at the beginning of a cycle, by selecting one or more additional days during the cycle, preferably one day in the middle of the cycle, on which the anti-progestogen is administered, whereas over the rest of an entire menstrual cycle (e.g. 28 days) desogestrel or 3-ketodesogestrel is administered as the progestogen at certain specified dosages, complete ovulation inhibition is achieved, while retaining good cycle control and almost completely decreasing the amount of spotting.
The invention thus includes a drug delivery system for contraceptive use containing daily oral dosage units, each unit containing a progestogen, and two or more units comprising an anti-progestogen, one of which is administered at the end and the others orderly divided through the cycle (if one: in the middle of the cycle).
The invention also includes a drug delivery system for HRT (hormone replacement therapy) containing daily oral dosage units, each unit comprising a progestogen with or without an estrogen or an estrogen only, and two or more dosage units comprising an anti-progestogen, one of which is preferably administered at the beginning and the others orderly divided through the cycle (if one: in the middle of the cycle).
In general terms the invention relates to a contraceptive and/or HRT (hormone replacement therapy) kit comprising sequential daily dosage units for oral administration each comprising as the sole contraceptively effective ingredient a progestogen, or as effective ingredient for HRT a progestogen with or without an estrogen or an estrogen alone, and further two or more units comprising an anti-progestogen.
If desired the kits may contain placebo pills to bridge two periods of administration of active ingredients. This is usual for contraceptive regimens containing less than 28 dosage units, in order to obtain a kit still having 28 pills (the usual cycle).
The invention also includes a pharmaceutical product (i.e. the dosage units or the package containing the dosage units), a method of using the product, and a process of manufacturing the pharmaceutical product.
The invention also includes a method of providing contraception and/or HRT for a pre-, peri-, or post-menopausal woman involving administering to the woman the above-mentioned regimens.
Progestogens for use with the invention are 3-keto-desogestrel (etonogestrel), desogestrel, gestodene, levonorgestel, norgestrel and other progestogens commonly used for contraception and HRT. Desogestrel has the chemical name 13-ethyl-11-methylene-18,19-di-nor-17xcex1-pregn-4-en-20-yn-17-ol, and is the preferred progestogen. Desogestrel is believed to be metabolized in the body into 3-ketodesogestrel. Preferably the dosage units contain 75 xcexcg of desogestrel or 3-ketodesogestrel, or an amount of other progestogens having the equivalent effect as 75 xcexcg of desogestrel. Based on practically applied doses, levonorgestrel, desogestrel, and 3-keto-desogestrel are relatively equipotent in progestogenic activity. Gestodene is approximately 1.5 times as potent as these compounds. Norgestrel is about one-half as potent as levonorgestrel.
The anti-progestogen can be an inhibitor of progesterone synthesis, such as epostane, azastene or trilostane (Creange, Contraception 24, 289, 1981; Drugs of the Future 7, 661, 1982, van der Spuy et al., Contraception 35, 111, 1987; U.S. Pat. No. 3,296,255) or a progesterone receptor antagonist, or any such pharmaceutically suitable agent that counteracts the normal biological activity of progesterone, such as antibodies or ligands bindable to progestogens or to the progesterone receptor.
A suitable anti-progestogen is a progesterone receptor antagonist. For example RU486, Onapristone, Org 31710 [(6xcex1,11xcex2,17xcex2)-11-(4-dimethylaminophenyl)-6-methyl-4xe2x80x2, 5xe2x80x2-dihydrospiro[estra-4.9-diene-17,2xe2x80x2-(3xe2x80x2H)-furan]-3-one], and Org 33628 [11xcex2,17xcex1)-11-(4-acetylphenyl)-17,23-epoxy-19,24-dinorchola-4,9,20-trien-3-one] are particularly suitable in the practice of the present invention.
Suitable amounts of anti-progestogen are for example 0.1 to 300 mg, and preferably 0.5 to 150 mg of Org 31710 or such amounts of other anti-progestogens which have equivalent activity. The anti-progestogen is administered at the beginning of the cycle, preferably on day 1, and in the middle of the cycle, preferably day 14. More generally, the first of the anti-progestogen dosage units may be administered between days 1 and 3 (the beginning of the cycle), and the second between days 12 and 16 (the middle of the cycle). In the case of more than one additional day of anti-progestagen administration, these additional days may be, e.g., in the middle of the remaining phases, i.e. anti-progestagen then is administered once a week. Maximally, the anti-progestagen can be administered every 4 days, i.e. for a cyclus of 28 days the number of dosage units comprising anti-progestagen is two to seven. Every 5-7 days is preferred, but it is most preferred that anti-progestagen be administered only one time additionally, i.e. in total twice a month. Particularly in the embodiments in which anti-progestagen is administered more than one time additionally, it is preferred to administer it simultaneously with progestagen, i.e. the anti-progestagen does not substitute the progestagen but comes in addition. It is important that the anti-progestagen is administered only one day in a row. For HRT regimens it is desired for the anti-progestogen to be dosed in as low an amount as is capable of inhibiting bleeding, without inducing menses.
In the method of this invention the contraceptive and/or HRT kit consists of four phases, in which the first phase is a single dosage unit comprising an anti-progestogen and optionally a progestogen, the second phase containing progestogen, estrogen or a mixture thereof, the third phase comprising an anti-progestogen and optionally a progestogen, and the fourth phase containing progestogen, estrogen or a mixture thereof.
Preferably the dosage of the anti-progestogen in the third and optional further phases is lower than the dosage of the anti-progestogen in the first phase. More preferably the first phase consists of 10 to 150 mg of Org 31710, and most preferably 25 mg of Org 31710, and the third phase (and any optional subsequent phase) consists of 0.5 to 25 mg, more preferably of 2.5 to 12.5 mg, and even more preferably of 5 mg of Org 31710. In the case of a more than four-phase regimen involving more than two times administration of anti-progestagen, the first phase dosage will generally be the same as above, but it is possible to further decrease the dosage in the subsequent phases.
For HRT regimens dosage units comprising the anti-progestogen units as above and units comprising an estrogen, progestogen or mixtures thereof are envisaged. Estrogens which can be used include 17xcex2-estradiol and ethinyl estradiol. Mestranol (17-xcex1-ethinyl estradiol 3-methylether) and conjugated estrogens are also useful estrogens. Suitable amounts of ethinyl estradiol per dosage unit are between 0.005 and 0.1 mg. Of course amounts having equivalent activity of other estrogens can also be used. As an approximation, 1 mg of 17xcex2-estradiol is equivalent in estrogenic activity to 0.015 mg of ethinyl estradiol and 0.030 mg of mestranol.
The progestogen and anti-progestogen are incorporated into dosage units for oral administration. The term xe2x80x9cdosage unitxe2x80x9d generally refers to physically discrete units suitable as unitary dosages for humans, each containing a predetermined quantity of active material calculated to produce the desired effect, for instance tablets, pills, powders, suppositories, capsules and the like.
Methods and compositions for making such dosage units are well-known to those skilled in the art. For example, conventional techniques for making tablets and pills, containing active ingredients, are described in the standard reference, Gennaro et al., Remington""s Pharmaceutical Sciences, (18th ed., Mack Publishing Company, 1990, see especially Part 8: Pharmaceutical Preparations and Their Manufacture).
For making dosage units, e.g. tablets, the use of conventional additives, e.g. fillers, colorants, polymeric binders and the like is contemplated. In general any pharmaceutically acceptable additive which does not interfere with the function of the active compounds can be used in the one or more of the compositions.
Suitable carriers with which the compositions can be administered include lactose, starch, cellulose derivatives and the like used in suitable amounts. Lactose is a preferred carrier. Mixtures of carriers can also be used.
A process of manufacturing the kit of the invention comprises mixing predetermined quantities of progestogen (for instance desogestrel, 3-ketodesogestrel, or mixtures thereof) or anti-progestogen (for instance Org 31710) with predetermined quantities of excipients and converting the mixture into dosage units containing progestogen or anti-progestogen.
For HRT regimens unit dosages may be obtained by mixing predetermined quantities of progestogen and estrogen.
Preferred kits contain a total of 20 to 32 of said daily sequential dosage units.
Converting the mixture into dosage units generally involves molding the mixture into a tablet, filling a capsule with a dried mixture, or filling a capsule with a wet mixture. A preferred process of manufacturing the pharmaceutical product according to the invention involves incorporating the desired dosages of contraceptive steroid (for example desogestrel, 3-ketodesogestrel, or mixtures thereof) into tablets by techniques such as wet granulation tableting techniques. The package containing the dosage units will contain between 7 and 180, preferably 28, dosage units.
While the description hereinbefore refers to daily dosage units making up the anticonceptive or HRT kit, the method of treatment according to the invention extends to any other suitable form of administration. Therefore, the invention relates to pharmaceutical preparations capable of releasing progestagen and anti-progestagen, optionally simultaneously, in accordance with the regimen described above. Thus the administration in four or more phases of anti-progestagen and progestagen can be effectuated not only through tablets, but also by means of an implant system, a vaginal ring, injectable systems, transdermal systems, or by any combination thereof (particularly: the progestagen administered as a tablet, the anti-progestagen in the form of a non-oral system such as an implant).


An arrangement for fixing a medical-technical sensor, particularly a pulsoximeter sensor, to a patient""s body part includes a carrier for supporting a sensor and a longitudinal opening for receiving the body part. The carrier includes a foam material part elastically deformable for the fixing. The deformation provides a force-accumulation arrangement. The medical-technical sensor for measuring physiological data can be combined with such arrangement. The sensor includes optical electronic measuring parts arranged on the carrier.

The present invention relates to an arrangement for fixing a medical-technical measuring device to a patient""s body part, and to medical-technical measuring device having such fixing arrangement, particularly a pulsoximeter sensor.
DE 37 03 458 C2 discloses a medical-technical measuring device including arrangement fixing it a body part of a patient, particularly to a finger, a toe, an arm or a leg. A first segment of a carrier means includes a longitudinal opening extending in a longitudinal direction to receive the body part, and supports the measuring means. A second segment, adjacent the first segment, extends around the periphery and is elastic. During stressing beyond the material elasticity of the first segment, the stresses pass to the second segment. The disclosed method of manufacture involves casting around the transmitter and receiver elements, during the manufacture of the carrier means.
U.S. Pat. No. 4,685,464 discloses a clothespin-like pulsoximeter. Two arms of a clamp-like carrier means can be brought into clamping contact on the body part of the patient.
The conventional fixing arrangements and measuring devices are disadvantageous in that they include a secure fixing obtained by introduction of a higher force level and essentially pointed or clamping fixing forces, which then, for example, can lead to disturbances of the blood circulation in the body part, or in that they guarantee good blood circulation in the body part by use of reduced fixing forces, which then frequently lead to the fixing arrangement or the measuring device becoming detached from the body part, particularly upon displacement of the body part. This latter arrangement can be an important disadvantage, particularly when it is used for infants or small children and for intensive care medicine. Also, the conventional devices are costly to manufacture and require a high degree of precision and high level of skill with their use.
The present invention involves an arrangement for fixing a medical-technical measuring device to the body as well as a medical-technical measuring device, which overcome the disadvantages of conventional arrangements and devices. Particularly, the present invention ensures a secure fixing, while preventing any disturbances of the blood circulation of the body part of the patient. In addition, the fixing arrangement and measuring device can be manufactured at low cost, and are to be simple to use and to clean.
In pulsoximetry, the oxygen content of the blood of a patient is determined. Preferably, a body part with good blood circulation is exposed to rays or even irradiated with light, for example, of two different wave lengths. The relative oxygen saturation of the blood is calculated from the absorption and/or reflection. Suitable body parts for this type of measuring are, for example, the ear and the nose separating wall, but particularly the extremities such as the fingers or toes. For such medical-technical measuring device, at least one optical transmitter element and at least one optical receiver element are preferably arranged on opposite sides of the body part. On the one hand, the blood circulation of the body part is not to be obstructed. On the other hand, the elements are to be sufficiently secured in their position relative to one another, particularly in their axial alignment, so that the measuring process is not at all negatively influenced even with frequent movements of the body part, for example in the case of infants and/or of intensive care patients.
The arrangement for fixing a medical-technical measuring device according to the present invention has carrier means including a foam part. At least on the surface of the carrier means turned toward or facing the body part, the carrier means is slightly elastically deformable to obtain the fixing. The deformation makes available a force-accumulating arrangement which brings about the fixing, so that a secure fixing is attained with essentially unimpaired blood circulation of the body part. Preferably, the foam of the carrier means completely surrounds the body part, conducting the fixing force over the entire surface of the body part, and particularly is configured as a sheathing or in cap-like configuration. The exterior surface of the carrier means and the interior surface formed by the longitudinal opening can be configured as cylindrical, conical or frustoconical. With the introduction of the body part into the longitudinal opening or the slipping of the carrier means over the body part, deformation of the foam occurs particularly in radial direction in relation to the longitudinal direction. The foam material thus has the advantageous property that it can be pressed together on one fragment of its volume, and thus, makes available a permanent force-accumulation arrangement.
The term xe2x80x9cfoam materialxe2x80x9d is not intended to mean the original material forming the foam, but rather is intended to mean the solid foam product itself, in other words the synthetically produced material of cellular structure. Among other things, rubber, a rubber-plastic mixture and particularly a synthetic resin or plastic can be considered as the raw material to make the foam material. Some synthetic foam materials, which can be used, are cited in Neumuller, Otto-Albrecht: Rompp Chemie-Lexikon, Stuttgart, Francksche Verlagsanstalt [Publisher], 8th Edition, page 3703, under the key word xe2x80x9cSchaumkunststoffexe2x80x9d [xe2x80x9cSynthetic foamxe2x80x9d]. Because of the low density of the foam material, both the device for the fixing and also the medical-technical measuring device are of low mass. The longitudinal opening can be a blind hole or a through-passage opening and can be arranged in the center or eccentrically in relation to the longitudinal axis of the carrier means. Preferably, in any case, the axis of the longitudinal opening extends parallel to the axis of the carrier means. The diameter of the longitudinal opening is preferably somewhat smaller than the diameter of the smallest body part to which the measuring device is to be affixed.
The foam material or the entire carrier means can be manufactured of a semifinished material by stamping or cutting, particularly with use of a water stream or a laser beam. Thus, both the density and the cell dimensions of the foam material, as well as the material of the foam itself, can be adapted optimally to the relevant particular use being proposed. Generally speaking, such manufactured foam material parts or carrier means have neither blind holes nor any structures deviating from a cylindrical shape.
With the foam material part having incisions originating from the longitudinal opening and extending at least some distance in the longitudinal direction, at least two segments are formed by the incisions around the periphery, and extend in peripheral direction. Potential tensile stresses generate a deformation such that disturbing the measuring method is prevented. The number of incisions and the number of segments formed by the incisions can be adapted to the dimensions and configuration of the body part.
The incisions extend radially through at least half of the thickness of the foam part. An appreciable compensation for the deformation of one segment is then guaranteed by the deformation of an adjacent segment. Thus a permanently reliable and tight contact of the foam material on the body part is guaranteed.
The segments are connected with one another on their exterior by a layer of foam material configured of one single piece with the segments. The exterior shape of the carrier means during introduction of the body part or while the arrangement is being slipped over a body part is then not varied noticeably. Optimum contact of the foam material on the body part is guaranteed on all sides. For example, in the case of a measuring device with optical electronic measuring means, when the body part is displaced or turned over, the light is reliably prevented from getting to the receiver either directly from the transmitter or through reflection. This feature can be attained either alternatively or as a supplement by the foam material being colored with a dye. The dye is adapted to an optical electronic measurement to be carried out by the measuring device. Particularly, the radiation originating from a transmitter element is essentially completely absorbed.
The permanently secure fixing is further improved by the shape of the longitudinal opening being designed to be the shape of the body part which will receive it. For example, the longitudinal opening to receive a finger or a toe can be configured in conical shape with at least two padding pieces or beads. The padding pieces or beads are arranged one behind the other in the direction of the longitudinal layout, separated from one another by a narrowed section and rounded either inward or outward.
The carrier means has a transverse opening into which the measuring means is to be inserted, particularly on opposite sides of the body part. A secure and, if necessary, detachable mounting of the measuring means and an exact axial alignment of one to the other are then guaranteed. By such detachable mounting of the measuring means, the carrier means can be exchanged simply and at low cost if it becomes necessary, for instance for hygienic requirements.
A connection to the measuring means can be attached to a point on the exterior of the carrier means. The arrangement for fixing to a body part and the associated measuring device are then simple to manage and operate. Furthermore, fatiguing bending stresses of the connecting line and the connection points are particularly avoided, whereupon the operation and maintenance costs of the measuring device are also lowered considerably. The mounting can be executed by catch devices configured, for example, of one piece and mounted on the exterior.
On its exterior side more distant from the body part, the carrier means can have a rigid casing around the foam material. The stability of the exterior shape of the carrier means as well as a sufficient level of fixing force are then guaranteed. The casing, for example, can be formed by a sheathing of plastic or metal. Alternatively or as a supplement, an integral or structural foam material with solid skin and cellular core, all of one piece can be formed. The exchangeability of the foam material is further simplified when the sheathing is of a plurality of parts, particularly when it can be opened for the introduction of the foam material. For example, the sheathing can have an articulation-like device so that it can be opened, which device is configured preferably of one or more of the sheathing parts integrated into one piece.
The present invention also relates to a medical-technical measuring device for measuring physiological data of a patient, particularly a pulsoximeter sensor, with a fixing arrangement as described above. The measuring device has optical electronic measuring means arranged on the carrier means. A measuring procedure yielding reliable physiological data is then guaranteed by using a measuring device configured according to the present invention. In addition, the measuring device according to the present invention is of low cost to manufacture and maintain, as well as being simple to use.
The measuring means can include at least one optical transmitter element and at least one optical receiver element. The elements are arranged along the same axis through a transverse opening on opposite sides of the carrier means. The axial alignment of transmitter and receiver elements is guaranteed even under the mechanical stress of the arrangement for the fixing, for example, during introduction of the body part or during slipping of the arrangement over the body part. The foam material of the carrier means is essentially impermeable for the radiation emitted from the optical electronic measuring means. Particularly, it can be tinted with a corresponding suitable dye. In this manner, erroneous measurements, occurring for example because of reflections of the emitted radiation on the foam material, are essentially excluded from occurring.

Arrangement for the fixing of a medical-technical measuring device as well as a medical-technical measuring device involving this sort of arrangement, particularly a pulsoximeter sensor


The invention relates to a novel process for the manufacture of functionalized polyphenylene ether resins through redistribution with a functionalized phenolic compound in the polyphenylene ether resin polymerization reaction solution without the addition of an added redistribution catalyst or promoter. The invention also relates to the functionalized polyphenylene ether resin made by the process as well as blends and articles containing the functionalized polyphenylene ether resin made by the process.

Not Applicable
1. Field of the Invention
The invention relates to a novel process for the manufacture of functionalized polyphenylene ether resins through redistribution with a functionalized phenolic compound in the polyphenylene ether resin polymerization reaction solution without the addition of an added redistribution catalyst or promoter.
The invention also relates to the functionalized polyphenylene ether resin made by the process as well as blends and articles containing the functionalized polyphenylene ether resin made by the process.
2. Brief Description of the Related Art
Polyphenylene ether resins (hereinafter xe2x80x9cPPExe2x80x9d) are commercially attractive materials because of their unique combination of physical, chemical, and electrical properties. Furthermore, the combination of PPE with other resins provides blends, which result in additional overall properties such as chemical resistance, high strength, and high flow.
One obstacle to blending PPE with other resins is the lack of compatibility between the resins. This lack of compatibility often manifests itself as delamination and/or poor physical properties such as, for example, poor ductility. One useful method known in the art to improve the compatibility between resins is to generate reaction products between the polymers that will act as compatibilizers for the resins. The reaction products are often thought of as copolymers of the resins.
One challenge in preparing the aforementioned reaction products is the need for reactive sites on the resins that will lead to the formation of reaction products. Some polymers such as polyamides inherently possess both amine and carboxylic acid endgroups that can readily undergo reaction with another resin containing a wide variety of possible reactive moieties. Polymers like PPE contain primarily phenolic endgroups and are in general not sufficiently reactive to result in the aforementioned reaction products in commercially feasible processes.
It should be apparent that methods and processes to introduce functionality into PPE are highly sought after. Redistribution, also known as equilibration, of phenolic compounds containing at least one functional moiety has been shown to afford PPE having desirable functionality. In the redistribution reaction of PPE with phenolic compounds, the PPE are usually split into shorter units with the phenolic compound incorporated in the PPE.
In the redistribution reactions illustrated in the art, the PPE is dissolved in a solvent with the phenolic compound and a catalyst, optionally with a promoter, is add to the reaction mixture. After heating at elevated temperatures, generally between 60xc2x0 C. and 80xc2x0 C., the redistributed PPE is isolated.
In order to utilize the redistribution technology in a commercially feasible manner, a process was needed that would minimize the need for additional processes, reaction vessels, and handling of PPE. It should be apparent that a process that would take advantage of the PPE polymerization process and associated mechanical equipment would be extremely advantageous.
The needs discussed above have been generally satisfied by the discovery of a process for preparing a functionalized PPE through redistribution with a phenolic compound prior to isolation of the PPE from the oxidative coupling reaction mixture and without the addition of a catalyst or a promoter. The oxidative coupling reaction conditions can be adjusted to afford sufficient in situ catalyst for the redistribution reaction.
The description that follows provides further details regarding various embodiments of the invention.
Not applicable
This invention provides for a process for the preparation of low molecular weight PPE, preferably about 0.05 dl/g and 0.5 dl/g, preferably about 0.08 dl/g and 0.4 dl/g, more preferably having an intrinsic viscosity between about 0.08 dl/g and 0.16 dl/g, by oxidative coupling at least one monovalent phenol species, preferably at least a portion of which have substitution in at least the two ortho positions and hydrogen or halogen in the para position, to produce a PPE having an intrinsic viscosity of greater than about 0.16 dl/g as measured in chloroform at 25xc2x0 C. using an oxygen containing gas and a complex metal-amine catalyst, preferably a copper (I)-amine catalyst, as the oxidizing agent, redistributing at least one additional phenol species to produce a PPE having an intrinsic viscosity within the range of about 0.05 dl/g and 0.5 dl/g, preferably about 0.08 dl/g and 0.4 dl/g, more preferably about 0.08 dl/g to about 0.16 dl/g, and extracting at least a portion of the metal catalyst as a metal-organic acid salt with an aqueous containing solution, and isolating the PPE through devolatilization of the reaction solvent. In one embodiment, the additional phenol species comprises a functionalized phenol species. In another embodiment, the additional phenol species is equilibrated into the PPE without additional initiator.
The PPE employed in the present invention are known polymers comprising a plurality of structural units of the formula
wherein each structural unit may be the same or different, and in each structural unit, each Q1 is independently halogen, primary or secondary lower alkyl (i.e., alkyl containing up to 7 carbon atoms), phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and each Q2 is independently hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy or halohydrocarbonoxy as defined for Q1. Most often, each Q1 is alkyl or phenyl, especially C1-4 alkyl, and each Q2 is hydrogen.
Both homopolymer and copolymer PPE are included. The preferred homopolymers are those containing 2,6-dimethyl-1,4-phenylene ether units. Suitable copolymers include random copolymers containing such units in combination with (for example) 2,3,6-trimethyl-1,4-phenylene ether units. Also included are PPE containing moieties prepared by grafting vinyl monomers or polymers such as polystyrenes and elastomers, as well as coupled PPE in which coupling agents such as low molecular weight polycarbonates, quinones, heterocycles and formals undergo reaction in known manner with the hydroxy groups of two poly(phenylene ether) chains to produce a higher molecular weight polymer, provided a substantial proportion of free OH groups remains.
The PPE are typically prepared by the oxidative coupling of at least one monohydroxyaromatic compound such as 2,6-xylenol, 2,3,6-trimethylphenol, or mixtures of the foregoing. Catalyst systems are generally employed for such coupling and they typically contain at least one heavy metal compound such as a copper, manganese, or cobalt compound, usually in combination with various other materials.
It will be apparent to those skilled in the art from the foregoing that the PPE contemplated in the present invention include all those presently known, irrespective of variations in structural units or ancillary chemical features.
The polymerization of the phenolic monomer may be carried out by adding the phenolic monomer or monomers to a suitable reaction solvent and preferably, a copper-amine catalyst. It is preferred to carry out the polymerization in the presence of a cupric salt-secondary amine catalyst such as, for example, cupric chloride and di-n-butylamine. The polymerizations are advantageously carried out in the presence of an inorganic alkali metal bromide or an alkaline earth metal bromide. The inorganic bromides may be used at a level of from about 0.1 mole to about 150 moles per 100 moles of phenolic monomer. These catalyst materials are described in U.S. Pat. No. 3,733,299 (Cooper et al.). Tetraalkylammonium salts may also be employed as promoters if desired. These promoters are disclosed in U.S. Pat. No. 3,988,297 (Bennett et al.).
The primary, secondary or tertiary amine components of the catalyst complex generally correspond to those disclosed in U.S. Pat. Nos. 3,306,874 and 3,306,875 (Hay). Illustrative members include aliphatic amines, including aliphatic mono- and di-amines, where the aliphatic group can be straight or branched chain hydrocarbon or cycloaliphatic. Preferred are aliphatic primary, secondary and tertiary monoamines and tertiary diamines. Especially preferred are mono-, di- and tri(lower) alkyl amines, the alkyl groups having from 1 to 6 carbon atoms. Typically, there can be used mono-, di- and tri-methyl, ethyl, n-propyl i-propyl, n-butyl substituted amines, mono- and di-cyclohexylamine, ethylmethyl amine, morpholine, N-(lower) alkyl cycloaliphatic amines, such as N-methylcyclohexylamine, N,Nxe2x80x2-dialkylethylenediamines, the N,Nxe2x80x2-dialkylpropanediamines, the N,N,N,xe2x80x2-trialkylpentanediamines, and the like. In addition, cyclic tertiary amines, such as pyridine, alpha-collidine, gamma picoline, and the like, can be used. Especially useful are N,N,Nxe2x80x2,Nxe2x80x2-tetraalkylethylenediamines, butane-diamines, and the like.
Mixtures of such primary, secondary and tertiary amines may be used. A preferred mono alkyl amine is n-butyl amine; a preferred dialkyl amine is di-n-butyl amine; and a preferred trialkyl amine is triethylamine. A preferred cyclic tertiary amine is pyridine. The concentration of primary and secondary amine in the reaction mixture may vary within wide limits, but is desirably added in low concentrations. A preferred range of non-tertiary amines comprises from about 2.0 to about 25.0 moles per 100 moles of monovalent phenol. In the case of a tertiary amine, the preferred range is considerably broader, and comprises from about 0.2 to about 1500 moles per 100 moles of monovalent phenol. With tertiary amines, if water is not removed from the reaction mixture, it is preferred to use from about 500 to about 1500 moles of amine per 100 moles of phenol. If water is removed from the reaction, then only about 10 moles of tertiary amine, e.g., triethylamine or triethylamine, per 100 moles of phenol need be used as a lower limit. Even smaller amounts of tertiary diamines, such as N,N,Nxe2x80x2Nxe2x80x2-tetramethylbutanediamine can be used, down to as low as about 0.2 mole per 100 moles of phenol.
Typical examples of cuprous salts and cupric salts suitable for the process are shown in the Hay patents. These salts include, for example, cuprous chloride, cuprous bromide, cuprous sulfate, cuprous azide, cuprous tetramine sulfate, cuprous acetate, cuprous butyrate, cuprous toluate, cupric chloride, cupric bromide, cupric sulfate, cupric azide, cupric tetramine sulfate, cupric acetate, cupric butyrate, cupric toluate, and the like. Preferred cuprous and cupric salts include the halides, alkanoates or sulfates, e.g., cuprous bromide and cuprous chloride, cupric bromide and cupric chloride, cupric sulfate, cupric fluoride, cuprous acetate and cupric acetate. With primary and secondary amines, the concentration of the copper salts is desirable maintained low and preferably varies from about 0.2 to 2.5 moles per 100 moles of monovalent phenol. With tertiary amines, the copper salt is preferable used in an amount providing from about 0.2 to about 15 moles per 100 moles of the monovalent phenol.
Cupric halides are generally preferred over cuprous halides for the preparation of the copper amine catalyst because of their lower cost. The use of the copper (I) species also greatly increases the rate of oxygen utilization in the early stages of the polymerization reaction and the lower oxygen concentration in the head space of the reactor helps in reducing the risk of fire or explosion in the reactor. A process for the preparation and use of suitable copper-amine catalysts is in U.S. Pat. No. 3,900,445 (Cooper et al.).
In the practice of the invention, the catalyst (also known as an initiator) for the redistribution reaction is preferably generated in situ during the oxidative coupling process. Backward dimer, tetramethyldiphenylquinone (TMDQ), is normally made during coupling of 2,6-dimethylphenol and is a preferred catalyst. Other diphenylquinones may also be present depending on the phenolic species being oxidatively coupled.
Reaction conditions that favor generation of the backward dimer are preferred and can be readily controlled. When the level of monomer is increased during the early stages of oxidation, higher levels of TMDQ are produced. Likewise, a slower initial reaction rate with the copper (I) based catalyst also results in an increased accumulation of unreacted monomer and an increase in the amount of TMDQ produced. The copper amine ratio affects the amount of TMDQ generated with a higher ratio of amine to copper favoring an increase in the amount of TMDQ. Additionally, allowing the reaction mixture to heat, preferably from the reaction exotherm, also results in higher levels of TMDQ. Generally, the reaction mixture is maintained between about 30xc2x0 and 45xc2x0 C., however allowing the temperature to increase to even 50xc2x0 C. results in an increase in the level of TMDQ. Preferably the level of catalyst is less than 10% by weight with respect to the PPE.
Numerous studies conducted to determine conditions that can lead to increased levels of backward dimer (e.g., TMDQ) during the oxidative coupling process have resulted in a number of other unexpected factors that affect the formation of backward dimer. First, increasing the ratio of phenolic monomer to solvent (e.g., 2,6-xylenol:toluene ratio) leads to higher backward dimer ratios as does a high addition rate of phenolic monomer to the reaction mixture. As previously discussed, increases in the reactor temperature also leads to increased levels of backward dimer. Finally, running the oxidative coupling at a lower percentage of oxygen in the reactor (i.e. a lower phenolic to oxygen ratio) also leads to increased amounts of backward dimer.
If no additional functionalized phenolic compound is added at the equilibration step of the process, the TMDQ (or any other backward dimer) becomes incorporated into the PPE and can lead to a high hydroxyl PPE. It should be clear that the present invention also includes processes to increase the hydroxyl level on PPE by increasing the level of backward dimer (e.g., TMDQ) during the oxidative coupling process and incorporating at least a portion of the TMDQ through redistribution (i.e. equilibration). For example, a PPE oxidative coupling reaction that has a TMDQ level of about six weight percent based on the weight of the PPE at the end of reaction had a hydroxyl number of about 360 xcexcmol/g after equilibration.
The polymerization reaction is preferably performed in a solvent. Suitable solvents are disclosed in the above-noted Hay patents. Aromatic solvents such as benzene, toluene, ethylbenzene, xylene, and o-dichlorobenzene are especially preferred, although tetrachloromethane, trichloromethane, dichloromethane, 1,2-dichloroethane and trichloroethylene may also be used. The weight ratio between solvent and monomer is normally in the range from 1:1 to 20:1, i.e., up to a maximum 20-fold excess of solvent. The ratio between solvent and monomer is preferably in the range from 1:1 to 10:1 by weight.
The temperature to carry out the polymerization stage of the invention generally ranges from about 0xc2x0 C. to about 95xc2x0 C. More preferably, the temperature range is from about 35xc2x0 C. to about 55xc2x0 C. with the higher reaction temperature near the end of reaction. At substantially higher temperatures, side reactions can occur leading to undesirable reaction by-products and at temperatures substantially lower, ice crystals form in the solution. As previously discussed, allowing the reaction mixture to increase above about 50xc2x0 C. results in an increase in the level of backward dimer produced that can be used to catalyze the redistribution reaction.
The process and reaction conditions for the polymerization, such as reaction time, temperature, oxygen flow rate and the like are modified based on the exact target molecular weight desired. The endpoint of the polymerization is conveniently determined with an in-line viscosity meter. Although other methods such as making molecular weight measurements, running to a predetermined reaction time, controlling to a specified endgroup concentration, or the oxygen concentration in solution may also be utilized.
After the end of the oxidative coupling reaction as determined by the desired molecular weight of the PPE, at least one phenolic compound is added to the reaction mixture and allowed to circulate while maintaining the temperature preferably between about 20xc2x0 and about 150xc2x0 C., preferably between about 60xc2x0 and 80xc2x0 C. The reaction mixture is maintained at temperature for about 30 to about 90 minutes, although longer times are possible. During this redistribution step, the flow of oxygen has been preferably halted as the oxidative coupling has been completed. Generally, higher redistribution conversions are obtained under air as opposed to nitrogen.
In the process of the invention, the functionalized phenolic compound is chosen from the following:
A) phenolic compounds with formula
xe2x80x83wherein R1 represents a hydrogen-atom or an alkyl group and X represents an allyl group, an amino group, a protected amino group (e.g., protected by a tertiary-butyl carbonate), a carboxyl group, a hydroxy group, an ester group or a thiol group, wherein R1 is an alkyl group when X represents an hydroxy group or an ester group, wherein X may be separated from the phenol ring through an alkyl group and wherein the total number of carbon atoms in the alkyl groups attached to the phenol ring is not more than six;
B) bisphenol compounds with formula
xe2x80x83wherein each X, independently of the other X represents a hydrogen atom, an allyl group, an amino group, a protected amino group (e.g., protected by a tertiary-butyl carbonate), a carboxyl group, a hydroxy group, an ester group or a thiol group, with the proviso that not more than one X group represents a hydrogen atom, R2 and R3 represent an hydrogen atom or an alkyl group with 1-6 carbon atoms and each R4 represents independently of the other R4 a hydrogen atom, a methyl group or an ethyl group;
C) a phenolic compound with at least one of the formulas:
xe2x80x83wherein m and n have values from 2-20;
D) phenolic compounds with formula
xe2x80x83wherein x has a value of 12-20 and y has a value of 1-7 or a derivative thereof;
E) multifunctional phenolic compounds with formula
xe2x80x83wherein R5 represents a hydrogen atom, an alkyl group, an allyl group, an amino group, a protected amino group (e.g., protected by a tert-butyl carbonate), a carboxyl group, a hydroxy group, an ester group or a thiol group; or
F) phenolic compounds with amino groups with formula
wherein R6 represents independently of one another a hydrogen atom, an alkyl group or a methylene phenol group.
At the end of the redistribution, the functionalized PPE has a lower intrinsic viscosity, and hence a lower molecular weight, than does the PPE at the end of the oxidative coupling reaction. The degree of the decrease is determined at least in part by the amount of phenolic compound utilized and the amount of catalyst, e.g., TMDQ, present. In a preferred embodiment, the functionalized PPE has a weight average molecular weight of at least 1000, preferably between about 3000 and about 70,000 as compared to polystyrene standards. In another preferred embodiment, the functionalized PPE has an intrinsic viscosity of between about 0.05 dl/g and 0.50 dl/g, preferably between about 0.08 dl/g and 0.30 dl/g as measured in chloroform at 30xc2x0 C. The PPE may have a bi-modal distribution of molecular weights.
Preferably after completion of the redistribution reaction, the complex catalyst is chelated to convert the catalyst into a water soluble metal complex. It is also possible to add the chelating agent with the phenolic compound or even before the phenolic compound. In either case, it is preferable to add the phenolic compound within a short time frame after the oxygen flow has been discontinued as the TMDQ will begin redistributing and can become consumed before serving as a catalyst for the phenolic compound.
Many diverse extractants or chelating agents may be used in the practice of the invention to complex with the catalyst. For example, sulfuric acid, acetic acid, ammonium salts, bisulfate salts and various chelating agents may be used. When these materials are added to a PPE reaction solution, the copper-amine catalyst becomes poisoned and further oxidation does not take place. Many different materials may be used but it is preferred to employ those chelating agents that are disclosed in U.S. Pat. No. 3,838,102 (Bennett et al.).
The useful chelating agents include polyfunctional carboxylic acid containing compounds such as, for example, sodium potassium tartrate, nitrilotriacetic acid (NTA), citric acid, glycine and especially preferably they will be selected from polyalkylenepolyamine polycarboxylic acids, aminopolycarboxylic acids, aminocarboxylic acids, aminopolycarboxylic acids, aminocarboxylic acids, polycarboxylic acids and their alkali metal, alkaline earth metal or mixed alkali metal-alkaline earth metal salts. The preferred agents include ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid and their salts. Especially preferred are ethylenediaminotetraacetic acid or a mono-, di-, tri- and tetrasodium salt thereof and the resulting copper complex can be referred to as a copper carboxylate complex.
The chelated metallic catalyst component can be extracted with the water produced in the polymerization reaction by through the use of a liquid/liquid centrifuge. The preferred extraction liquid for use in the process of the invention is an aqueous solution of lower alkanol, i.e., a mixture of water and an alkanol having from 1 to about 4 carbon atoms. Generally from about 1% to about 80% by volume of an alkanol or glycol may be employed. These ratios may vary from about 0.01:1 to about 10:1 parts by volume of aqueous liquid extractant to discrete organic phase.
The reaction media generally comprises an aqueous environment. Anti-solvents can also be utilized in combination with the aqueous media to help drive the precipitation of the copper (I) species. The selection of an appropriate anti-solvent is based partially on the solubility co-efficient of the copper (I) species that is being precipitated. The halides are highly insoluble in water, log K[sp] values at 25xc2x0 C. are xe2x80x944.49, xe2x80x948.23 and xe2x80x9411.96 for CuCl, CuBr and CuI, respectively. Solubility in water is increased by the presence of excess of halide ions due to the formation of, e.g., CuCl2, CuCl3, and CuCl4 and by other complexing species. Non-limiting examples of anti-solvents would comprise low molecular weight alkyl and aromatic hydrocarbons, ketones, alcohols and the like which in themselves would have some solubility in the aqueous solution. One skilled in the art would be able to select an appropriate type and amount of anti-solvent, if any was utilized.
After removal of the catalyst, the PPE containing solution is concentrated to a higher solids level as part of the isolation of the PPE. Precipitation using standard non-solvent techniques typical for PPE having I.V.""s greater than 0.28 dl/g are not generally useful for isolation of low molecular weight PPE due to the small PPE particle size and friability of the particles. Very low yields are obtained with undesirable fractionation of oligomeric species. A total isolation process is preferred for isolating the PPE. As part of the total isolation, a portion of the solvent is preferably removed in order to reduce the solvent load on the total isolation equipment.
Concentration of the PPE containing solution is accomplished by reducing the pressure in a solvent flash vessel while preferably increasing the temperature of the PPE containing solution. Pressures of about 35 to 50 bar are desirable with solution temperatures increased to at least 200xc2x0 C., preferably of at least 230xc2x0 C. A solids level of PPE of at least 55%, preferably of at least 65% or higher is desirable.
The isolation of the PPE is typically carried out in a devolatilizing extruder although other methods involving spray drying, wiped film evaporators, flake evaporators, and flash vessels with melt pumps, including various combinations involving these methods are also useful and in some instances preferred. As previously described, total isolation is preferably from the viewpoint that oligomeric species are not removed to the same degree as with precipitation. Likewise, isolation yields are extremely high and are near quantitative. These techniques require however that the catalyst removal be completed in the prior process steps, as any catalyst remaining in solution will necessarily be isolated in the PPE.
Devolatilizing extruders and processes are known in the art and typically involve a twin-screw extruder equipped with multiple venting sections for solvent removal. In the practice of the present invention, the preheated concentrated solution containing the PPE is fed into the devolatilizing extruder and maintained at a temperature less than about 275xc2x0 C., and preferably less than about 250xc2x0 C., and most preferably between about 185-220xc2x0 C. with pressures in the vacuum vent of less than about 1 bar. The resultant solvent level is reduced to less than about 1200 ppm, preferably less than about 600 ppm, and most preferably less than about 400 ppm.
When using a devolatilization extruder for the total isolation of the PPE, it was found that traditional underwater or water spray cooling of strands of extrudate followed by chopping the extrudate into pellets gave unacceptable results presumably due to the low melt strength and inherent brittle nature of low molecular weight PPE. It was found that special pelletization techniques could overcome these difficulties. Useful techniques include die-face pelletization, including underwater pelletization and flaking, declining angle strand pelletization using water spraying, and vibration drop pelletization with underwater pelletization especially suitable.
It was unexpectedly found that underwater pelletization resulted in a significantly lower color in the PPE as compared to the standard stranding with water/air cooling followed by pelletization techniques. Yellowness index (YI) numbers of less than 30, and even less than 25 are achievable as compared to YI greater than 50 achieved with the standard stranding technique. It should be apparent that the present process affords a method of preparing a PPE with a YI of less than about 30, preferably less than about 25.
The collected PPE pellets can be dried using techniques standard in the art including centrifugal dryers, batch or continuous oven dryers, fluid beds, and the like. Determination of an appropriate set of conditions can be readily determined by one of skill in the art without undue experimentation.
One unexpected advantage of the present invention to make functionalized PPE is using the inherent backward dimer produced in situ by the oxidative coupling reaction to catalyze the redistribution reaction during the polymerization reaction process without a prior isolation of the PPE. This process has advantages for cost reduction simply by reducing the number of handling steps involved. Moreover, the PPE is subject to fewer heat treatments than isolating the PPE followed by re-dissolving the PPE into a suitable solvent for redistribution. The process also affords a method to make a low molecular weight (i.e. PPE with an intrinsic viscosity between about 0.08 dl/g and about 0.16 dl/g) functionalized PPE.
All patents cited by reference are incorporated herein by reference.

Process for the manufacture of low molecular weight polyphenylene ether resins through redistribution