A process for fluidizing bisphenol dust is disclosed. The process entails adding 0.1 to 10 parts by weight of water per 1 part by weight of bisphenol dust. Also disclosed is a process for preparing a bisphenol wherein the fluidized bisphenol dust according to the invention is introduced before, during or after reaction of a phenol with a carbonyl compound.

The present invention provides fluidised bisphenol dust containing bisphenol dust and water, a process for preparing this and a process for preparing a bisphenol, wherein fluidised bisphenol dust is supplied to the process.
Bis(4-hydroxyaryl)alkanes, called bisphenols in the following, are important as starting materials or as intermediates for preparing a large number of commercial products. Bisphenols can be prepared by the condensation of phenols and carbonyl compounds. Substituted or unsubstituted phenols may be used.
The condensation product from the reaction between phenol and acetone, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A, BPA), is of particular industrial importance. BPA is used as the starting material for preparing many different types of polymer materials such as, for example, polyarylates, polyetherimides, polysulfones and modified phenol/formaldehyde resins. Preferred areas of application include the preparation of epoxy resins and polycarbonates.
Processes for preparing bisphenols by acid catalysed reaction of phenols with carbonyl compounds are known, for example, from U.S. Pat. No. 2,775,620 and EP-A-0 342 758.
Bisphenols of the general structure may be prepared by processes which are analogous to the processes for preparing BPA.
Bisphenols and in particular bisphenol A are advantageously converted into the form of so-called prills (prills are spherical solid particles which may be prepared by solidifying molten droplets in a stream of gas) or flakes. This enables simple storage, simple transport and simple handling procedures.
When producing bisphenol prills and bisphenol flakes or when otherwise handling bisphenols, a fine bisphenol dust is produced which consists of high purity bisphenol. The dust is tacky and difficult to handle. Handling this dust involves the risk of dust explosions. For this reason, the bisphenol dust is usually disposed of and, for example, incinerated, which entails a costly manual handling procedure and extensive safety precautions due to the risk of dust explosions. This has the disadvantage that disposal of the dust represents destruction of the valuable raw material bisphenol and in addition this procedure is not economically viable due to the high handling costs.
The present invention is therefore based on the object of providing a process for simplifying the handling of bisphenol dust and the possibility of making economic use of the dust.
This object is achieved by the provision of a process for fluidising bisphenol dust. This process enables the supply of bisphenol dust to the process for preparing bisphenols.
Thus, the invention provides a process for fluidising bisphenol dust, consisting of adding 0.1 to 10 parts by weight of water per 1 part by weight of bisphenol dust.
The invention also provides fluidised bisphenol dust containing 0.1 to 10 parts by weight of water per 1 part by weight of bisphenol dust.
The invention also provides a process for preparing a bisphenol, wherein fluidised bisphenol dust containing 0.1 to 10 parts by weight of water per 1 part by weight of bisphenol dust is supplied to the process before, during or after reaction of a phenol with a carbonyl compound.
Bisphenols in accordance with the invention are any bisphenols at all. Bisphenol A is preferred.
Phenols in accordance with the invention are any substituted phenols at all, unsubstituted phenol being preferred.
Carbonyl compounds in accordance with the invention are any carbonyl compounds at all. Acetone is preferred.
The amount of water used according to the invention is 0.1 to 10 parts by weight, preferably 0.15 to 1 part by weight, particularly preferably 0.2 to 0.4 parts by weight per 1 part by weight of bisphenol.
The fluidised bisphenol dust may preferably be supplied to the process for preparing a bisphenol without removing the water.
The fluidised bisphenol dust is preferably dissolved, preferably in a phenol, before being supplied to the process for preparing a bisphenol. This phenol is preferably the same phenol which is used in the process for preparing the bisphenol.
Supplying the fluidised bisphenol dust to the process for preparing a bisphenol may take place at any point during the process for preparing the bisphenol. Supply preferably takes place at the crystallisation stage in the process for preparing a bisphenol. Another preferred embodiment of the process is that in which supply of the fluidised bisphenol dust takes place at the mother liquor dewatering stage in the process for preparing the bisphenol.
In a preferred embodiment of the present invention, the bisphenol dust has a particle size of less than 1 mm, particularly preferably of less than 0.5 mm, very particularly preferably of less than 50 xcexcm.
According to the invention, the particles which form the bisphenol dust may have any shape at all. They preferably have the form of fragments of geometric shapes, for example fragments of platelets or spheres.
According to the invention, fluidisation is understood to be production of the ability to flow. The ability to flow in this connection means, for example, that the fluidised bisphenol dust, under the effects of only the force of gravity, flows through a 50 cm long tube with a diameter of 20 cm at a sufficiently rapid rate, preferably at a rate greater than 300 kg per 10 minutes.
Bisphenol dust according to the invention preferably has a purity of greater than 95 wt. %.
Bisphenol dust according to the invention may also contain isomers and secondary products which are produced during the preparation of bisphenol.
In particular, so-called xe2x80x9cstart-up materialxe2x80x9d, which is produced in the form of a dust when starting up bisphenol A preparation, is also to be included within the expression bisphenol dust.
The process according to the invention for preparing a bisphenol, wherein fluidised bisphenol dust is supplied to the process before, during or after reaction of a phenol with a carbonyl compound, is preferably performed in such a way that the amount of bisphenol dust supplied to the process is substantially less than the amount of bisphenol produced overall by the process. The amount of bisphenol dust supplied is preferably less than 10% of the amount of bisphenol prepared by the process.
The process according to the invention has a number of advantages. The bisphenol dust fluidised with water does not emit any dust to the surrounding atmosphere when it is handled, as does the same non-fluidised bisphenol dust when it is handled. This means that there is no longer any risk of dust explosions. As a result of the possibility of supplying the fluidised bisphenol dust to the process for preparing bisphenol, difficult and expensive waste disposal of the dust is not required. The valuable raw material bisphenol is recovered.
The process according to the invention for preparing BPA is preferably based on the acid catalysed reaction of phenol and acetone, wherein there is preferably a ratio by weight of phenol to acetone in the reaction of greater than 5:1. The acid catalysts used may be homogeneous or else heterogeneous Brxc3x6nsted acids or Lewis acids, that is, for example, strong inorganic acids such as hydrochloric acid or sulfuric acid. Gel-like or macroporous sulfonated cross-linked polystyrene resins (acid ion-exchangers) are preferably used. The following details refer to a process for preparation which makes use of acid ion exchangers as catalysts.
In order to produce higher selectivity, the reaction of phenol and acetone may be performed in the presence of suitable mercapto compounds as co-catalysts. These may either be homogeneously dissolved in the reaction solution or be fixed to the sulfonated polystyrene matrix via ionic or covalent bonds. The reaction unit is preferably a layer bed or a fluidised bed which is flowed through either upwards or downwards, or a column of the reactive distillation column type.
When reacting phenol and acetone in the presence of acid catalysts and mercapto compounds as co-catalysts, a product mixture is produced which contains, apart from unreacted phenol and optionally acetone, primarily BPA and water. In addition small amounts of typical secondary products of the condensation also appear, that is, for example, 2-(4-hydroxyphenyl)-2-(2-hydroxyphenyl)propane (o,p-BPA), substituted indanes, hydroxyphenyl indanols, hydroxyphenyl chromanes, substituted xanthenes and more highly condensed compounds with three or more phenyl rings in the molecular structure.
The secondary products mentioned such as also water, phenol and acetone, may impair the suitability of the BPA for preparing polymers and have to be removed by suitable methods. High purity requirements are usually specified for the raw material BPA, in particular for preparing polycarbonate.
The working up and purification of BPA is usually performed by a multi-stage cascade of suitable purification processes such as, for example, suspension crystallisation, melt crystallisation, distillation and desorption. In an industrially preferred embodiment, the BPA is separated from the reaction mixture in the form of an approximately equimolar crystalline adduct with phenol by cooling the reaction mixture while the BPA/phenol adduct crystallises out. Crystallisation is preferably performed as suspension crystallisation. Suspension crystallisation is understood to be crystallisation from a liquid, wherein the crystals form a suspension with the liquid. The BPA/phenol adduct crystals are then separated from the liquid phase using suitable equipment for solid/liquid separation such as rotary filters or centrifuges and then subjected to further purification, if so required. The adduct crystals obtained have a purity of typically greater than 99 wt. % of BPA with respect to the secondary components, with a phenol content of about 40 wt. %. Impurities which adhere to the surface of the adduct crystals can be removed by washing with suitable solutions which typically contain one or more components from the group consisting of acetone, water, phenol, BPA and secondary components.
The liquid stream (mother liquor) produced during liquid/solid separation contains phenol, BPA, water produced during reaction and unreacted acetone and is enriched with the secondary components typically produced during the preparation of BPA. In a preferred embodiment, this mother liquor is recycled to the reaction unit. In order to maintain the catalytic activity of the acid ion exchanger, the water produced is first removed, preferably by distillation, wherein any acetone still present is optionally also removed from the mother liquor. The dewatered reaction stream obtained in this way is topped up with phenol and acetone and returned to the reaction unit. Alternatively, water and acetone may be entirely or partly removed by distillation before performing suspension crystallisation of the BPA/phenol adduct.
Some of the phenol present in the reaction solution may also be removed by distillation during the distillation steps mentioned above.
The problem with this type of circulatory mode of operation is that secondary products from BPA preparation are enriched in the circulation stream and can lead to deactivation of the catalyst system. In order to avoid excessive enrichment of secondary components in the circulation stream, some of the circulation stream, optionally after partial or complete recovery of phenol by distillation, is removed from the process chain as BPA resin.
In addition it has proved advantageous to pass some or the entire amount of the circulation stream through a rearrangement unit filled with acid ion exchanger after the solid/liquid separation stage and before or after the removal of water and residual acetone. This unit is generally operated at higher temperatures than the reaction unit. Some of the secondary components from BPA preparation present in the circulation stream are isomerised to BPA in this rearrangement unit under the conditions maintained there so that the overall yield of BPA can be increased.
The BPA/phenol adduct crystals obtained following suspension crystallisation of the reaction solution and solid/liquid separation, as described above, are taken to further purification steps if this is required, wherein the removal of phenol and optionally a reduction in the concentration of secondary components is achieved. The major proportion of the phenol is preferably removed.
Thus, the adduct crystals may be recrystallised, for example, from phenol, from organic solvents, from water or from mixtures of the previously mentioned compounds in accordance with a suspension crystallisation procedure. The phenol present in the adduct crystals may also be entirely or partly removed by the choice of a suitable solvent. Phenol optionally remaining in the BPA after recrystallisation may then be entirely removed by using suitable methods of distillation, desorption or extraction.
Alternatively, phenol may also be removed first from the adduct crystals. Preferred methods for this are desorption of the molten material using hot inert gases, vacuum distillation or a combination of the methods mentioned. It is possible to obtain BPA with a residual phenol content of less than 100 ppm from the adduct crystals in this way. By means of suitable reaction management and optionally the addition of stabilisers, the BPA is not broken down to any noticeable extent under the effects of the heat applied during the removal of phenol by distillation or by desorption.
Depending on the process conditions during suspension crystallisation from the reaction solution and the way solid/liquid separation and crystal growth are performed, BPA is obtained, after removal of phenol from the adduct crystals, which is suitable for preparing polymer materials. In particular for the preparation of high quality materials such as polycarbonate, it may be necessary to take the BPA obtained after the removal of phenol to a further purification operation Final purification may be performed by suspension crystallisation from water or suitable organic solvents, melt crystallisation in the form of a static or dynamic layer crystallisation process, extraction with water, aqueous neutral, acid or basic salt solutions or suitable organic solvents or in the form of a single-stage or multi-stage distillation process. By performing the purification operations mentioned, or a suitable combination of these, it is possible to obtain BPA with a purity greater than 99.9 wt. % which is particularly suitable for preparing high quality polymer materials.
In a preferred embodiment of the present invention, the bisphenol dust fluidised with water is converted in a vessel into which pure phenol or a phenol/water mixture has initially been introduced. If phenol/water mixtures are initially introduced, these preferably consist of a mixture with a ratio by weight of phenol to water of 9:1 to 1:9.
The present invention is explained in the following with reference to a drawing (FIG. 1). The drawing represents a preferred embodiment of the invention. The invention is not restricted to this preferred embodiment.
The bisphenol A dust is located in a storage container 3. This is a bag-like container made of a plastics fabric with a total internal volume of about 1 m3 and with a discharge opening at the base. This storage container is called a xe2x80x9cbig bagxe2x80x9d. The discharge opening at the base of the big bag is pulled over opening 2 in storage tank 1. Water is sprayed in at the lower end of storage container 3, via pipe 4 which terminates in nozzle 5. This causes fluidisation of the bisphenol dust in storage container 3 and the dust falls into storage tank 1 under the effects of gravity. Storage tank 1 is provided with a stirrer 6 driven by a motor 7, by means of which the fluidised bisphenol dust can be homogenised. Nitrogen, as an inert gas, is supplied to the system via opening 8.
The invention is explained in the following by means of examples. The invention is not restricted to these examples.


An ambulatory dialysis system and connector which effectively prevents peritoneal infections such as peritonitis. The connector is comprised of a cylinder containing a disinfecting solution which continuously bathes the male and female connectors of a tube during use. A highly absorbent material is packed in the cylinder and saturated with a disinfectant and bathes the male and female connectors when connection is made and continually bathes them during use. A connection is provided by a male fitting on the end of a tube connected to a container of dialysate fluid or an abdominal opposing tube. A male connector is inserted into the female connector through the cylinder containing the absorbent material saturated with the disinfectant. The absorbent material is packed such that the male connector contacts the absorbent material during insertion to disinfect the opposing ends simultaneously while connection is being made. Once the dialysate fluid is delivered to the patient through the connector, the tube may be pulled off the outer end of the male connector to remove the empty containers. The male connector is then sealed and capped.

This invention relates to connectors for use with ambulatory dialysis devices and more particularly relates to an apparatus which disinfects the connection during connection and use.
There is a new system available for treating patients with loss of kidney function in which a container or bag of dialysate fluid is connected to the abdominal cavity for the purpose of peritoneal dialysis. In this system, the container with the dialysate fluid is connected to a permanent abdominal tube and the dialysate fluid is allowed to flow into the peritoneal cavity. The container and the tubing are then wound around the waist and tied. The dialysate fluid is allowed to remain in the peritoneal cavity for a period of time, allowing toxic waste and water to pass into the fluid. At the end of a predetermined period of time, the container is lowered and the fluid is allowed to flow out and back into the original container. The container is then disconnected and discarded and a new container of dialysate fluid attached to the permanent abdominal tube and the process is repeated.
A frequent problem which occurs from this method of peritoneal dialysis is the danger of peritoneal infection or peritonitis which is extremely high, due to the disconnecting and reattaching of containers with the dialysate fluid. These infections have been occurring even when extreme caution has been taken in making these connections and disconnections. The present method of making the interchange is to thoroughly cleanse the ends of the tubes connected respectively to the container of dialysate fluid and the abdominal connector before the connection is made. Further, as another precaution, the connection is made with surgically sterile rubber gloves to prevent or guard against any possible peritoneal invasion of bacteria.
Even with these precautions, incidents of peritoneal infection or peritonitis are still high. It would be advantageous if the disconnection and reconnection could be made without going through the time-consuming and very great inconveniencing process of putting on surgically sterile gloves, cleaning both tubes, and then connecting a new container of dialysate fluid. It would also be advantageous if the necessity for carrying around the empty container could be eliminated.

Ambulatory dialysis system and connector


A self-contained photohardenable imaging assembly comprising a first transparent polymeric film support, an imaging layer comprising a plurality of photosensitive microcapsules, a developer material and an adhesion promoter, and a second support which may be transparent or opaque is disclosed. Upon image-wise exposure and image development, an image forms in the imaging layer sealed between the supports to form an integral unit having improved peel strength.

The present invention relates to a self-contained imaging assembly and, more particularly, to a self-contained imaging assembly exhibiting improved peel resistance. This invention is an improvement in the invention described in commonly assigned U.S. Pat. Nos. 4,440,846 and 5,783,353, which disclose self-contained imaging assemblies in which a layer of microcapsules containing a chromogenic material and a photohardenable or photosoftenable composition, and a developer, which may be in the same or a separate layer from the microcapsules, is image-wise exposed, the microcapsules ruptured, and an image is produced by the differential reaction of a chromogenic material and the developer. U.S. Pat. No. 5,783,353 more specifically discloses a self-contained media in which the photosensitive microcapsules and the developer are sealed between two plastic films such that the user never comes into contact with the chemicals which form the image unless the media is deliberately destroyed. It would be desirable to have a composite media similar to that disclosed in U.S. Pat. No. 5,783,353 which provides an imaging assembly having increased peel strength without adversely affecting the imaging characteristics.
In the self-contained imaging system of the present invention, the imaging layer comprises a developer, photohardenable microcapsules and an adhesion promoter. The imaging layer is sealed between two support members to form an integral unit having improved peel strength. This sealed format is advantageous because it prevents the developer material and the contents of the microcapsules from contacting persons during handling and, depending on the nature of the supports, it may also prevent oxygen from permeating into the photohardenable material which may improve film speed and the stability of the image. The term xe2x80x9csealedxe2x80x9d as used herein refers to a seal which is designed as a nontemporary seal which results in destruction of the imaging assembly if the seal is broken. Adhesion promoters used in accordance with the present invention increase cohesion and adhesion within and between the layers of the composite imaging sheet to produce an imaging system having overall improved peel strength. The peel strength provides an indication of the integrity of the composite, self-contained imaging system. Increasing the peel strength of the imaging system insures that the benefits associated with having a sealed system are not compromised. The imaging system of the present invention exhibits superior temperature and humidity performance as compared to prior art systems.
In the imaging assembly of the invention, the previously mentioned first support is transparent and the second support may be transparent or opaque. In the latter case, an image is provided against a white background as viewed through the transparent support and in the former case a transparency is provided in which the image is viewed as a transparency preferably using an overhead or slide projector. Sometimes herein the first support may be referred to as the xe2x80x9cfrontxe2x80x9d support and the second support may be referred to as the xe2x80x9cbackxe2x80x9d support.
In order to insure that the imaging system is effectively sealed between the supports, a subbing layer is provided between the supports, a subbing layer is provided between one of the supports and the imaging layer and an adhesive is provided between the other support and the imaging layer. For optical clarity, the subbing layer will typically be located between the first support and the imaging layer. However, which support receives the subbing layer and which support receives the adhesive is a function of which support is coated with the wet imaging layer composition and which is assembled with the coated and dried imaging layer. The support which is coated with the imaging layer composition (which is typically the front support) will be provided with the subbing layer and the support which is assembled with the dried imaging layer will receive the adhesive.
The use of an imaging layer containing both the microcapsules and the developer is desirable because the image is formed in direct contact with the front transparent support through which the image is viewed. It has been found that this provides better image quality than, for example, providing a developer layer which overlies a separate layer of microcapsules, because the assembly can be exposed and viewed from the same side, the image can be viewed against a white background (when the back support is opaque) and, the image lies directly under the support through which it is viewed where it is most intense.
Applicants have discovered that the cohesive strength of the imaging layer containing both the microcapsules and the developer in prior art systems is less than the adhesive bonding strength between any two adjacent layers of the imaging system. Accordingly, the imaging layer is the weak link in the composite structure and tends to separate first when the imaging system is subjected to a peeling force. It would be desirable to have the imaging layer remain intact upon application of a peeling force to the imaging system. In this way the components of the microcapsules and the developer remain sequestered in the imaging layer where they are less likely to come in contact with persons handling the media. In accordance with the present invention, an adhesion promoter is added to the imaging layer to increase cohesion within the imaging layer as well as increase adhesion of the imaging layer to the adjacent layers of the imaging system. The overall increase in peel strength of the imaging system insures that the integrity of the system is maintained. The increased integrity of the sealed imaging system of the present invention also provides benefits in the form of superior temperature and humidity performance.
To record images the imaging material can be scanned with an LED print head and developed by application of pressure to the unit. An image appears on the face of the unit. The media can be printed using a printer which incorporates an LED print head in combination with one LED/developer head of the type described in U.S. Pat. No. 5,550,627. Of course, the media can be exposed and developed using any of the exposure and developing equipment that is taught in the art as it relates to imaging materials employing photosensitive microcapsules of this type, e.g., laser scan, LCD, laser-addressed LCD, reflection imaging, etc. Other development devices such as pressure roller development could be used.
In accordance with one embodiment of the present invention, a self-contained imaging system 1 comprises in order: a first transparent support 10, a subbing layer 11, an imaging composition 12 comprising photohardenable microcapsules 14 and a developer material 16, a layer of adhesive 18, and a second support 20 which may or may not contain an opacifying agent 26.
Images are formed in the present invention in the same manner as described in U.S. Pat. No. 4,440,846. By image-wise exposing this unit to actinic radiation, the microcapsules are differentially hardened in the exposed areas as taught in U.S. Pat. No. 4,440,846. The exposed unit is subjected to pressure to rupture the microcapsules.
The self-contained imaging system after exposure and rupture of the microcapsules, ruptured microcapsules 22 release a color forming agent, whereupon the developer material 16 reacts with the color forming agent to form an image 24. The image formed is viewed through the transparent support 10 against the support 20 which can contain a white pigment. Typically, the microcapsules will consist of three sets of microcapsules sensitive respectively to red, green and blue light and containing cyan, magenta and yellow color formers, respectively, as taught in U.S. Pat. No. 4,772,541. Also useful in the present invention is a silver-based photohardenable microencapsulated system such as that described in U.S. Pat. Nos. 4,912,011; 5,091,280 and 5,118,590 and other patents assigned to Fuji Photo Film Co. Preferably a direct digital transmission imaging technique is employed using a modulated LED print head as mentioned above.
Imaging layer 12 typically contains about 20 to 80% (dry weight) of the developer, about 80 to 20% (dry weight) microcapsules, about 0 to 20% binder and about 0.01 to 10%, preferably 0.5 to 5% of an adhesion promoter. The layer is typically applied in a dry coat weight of about 8 to 20 g/m2. Examples of such a coating formulations are illustrated in the Examples below. Binder materials which may be utilized include polyvinyl alcohol, polyacrylamide, and acrylic latices.
In the self-contained photohardenable imaging assembly the first transparent support 10 through which the image is viewed can be formed from any transparent polymeric film. A film will be selected which provides good photographic quality when viewing the image. Preferably, a film will be used which is resistant to yellowing. The first support 10 is typically a transparent polyethylene terephthalate (PET) support.
The second support 20 is preferably an opaque support such as polyethylene terephthalate (PET) containing an opacifying agent, paper or paper lined with film (polyethylene, polypropylene, polyester, etc.). Most preferably the opaque support is a polyethylene terephthalate support containing about 10% titanium dioxide which provides a bright white opaque support. This support is commercially available from ICI, Ltd. under the product designation Melinex. Typically, each of the front and back PET supports has a thickness of about 2 to 4 mils.
Generally, the opaque support will be available commercially. Some other products which are useful include paper cardboard, polyethylene, polyethylene-coated paper, etc. Opaque films are composites or admixtures of the polymer and the pigment in a single layer, films or coated papers. Alternatively, the opacifying agent can be provided in a separate layer underlying or overlying a polymer film such as PET. The opacifying agent employed in these materials is an inert, light-reflecting material which exhibits a white opaque background. Materials useful as the opacifying agent include inert, light-scattering white pigments such as titanium dioxide, magnesium carbonate or barium sulfate. In a preferred embodiment the opacifying agent is titanium dioxide.
In a preferred embodiment, the opaque second support is sufficiently opaque so that when a self-contained imaging sheet is exposed to radiation through the transparent support, the opaque support is effective to prevent the radiation from penetrating to other imaging sheets which may be stacked behind the imaging sheet during the exposure step. However, if the units are not exposed in a stacked format, the opacity of the support is not critical so long as the support provides the desired background. When both supports are transparent, if they are exposed in a stacked format, each self-contained imaging assembly must be separated from the other by an opaque member such as an opaque sheet or backing which is easily separated from the imaging sheet.
In an alternate embodiment, the imaging layer of the present invention is employed in the construction of a two-sided imaging material in accordance with commonly assigned U.S. Pat. No. 6,037,094. The two-sided imaging material comprises a pair of transparent supports, an opaque support and an imaging layer disposed between each transparent support and the opaque support. The benefits provided by the imaging layer of the present invention are particularly useful in a two-sided imaging material. Adhesion and cohesion characteristics of the composite coating are believed to be more important in a two-sided imaging material because of the additional layers involved in the construction of the imaging assembly.
Adhesion promoters useful in the present invention are materials which improve the cohesive strength of the imaging layer and the adhesion of the imaging layer to other layers in the imaging system without adversely affecting photographic characteristics. Classes of compounds which can be used as adhesion promoters in accordance with the present invention include bis-benzoxazoles, phenylcoumarins, bis-(styryl)biphenyls and triazinyl derivatives of diaminostilbenedisulphonic acids.
The bis-benzoxazole type of adhesion promoters have the general formula (I):
The phenylcoumarins have the general formula (II):
These phenylcoumarins include triazine-phenylcoumarins, benzotriazole-phenylcoumarins and naphtotriazole-phenylcoumarins.
The bis-(styryl)biphenyl type of adhesion promoters have the general formula (III):
The triazinyl derivatives of diaminostilbenedisulphonic acids have the general formula (IV):
Wherein each R independently represents alkyl, alkoxy, phenyls, carboxylic, sulphonic, phosphoric groups, etc. These compounds can be modified appropriately with most organic functional groups for other desired properties.
These compounds are also useful as UV absorbers and have typically been incorporated into the developer layer to prevent yellowing. Surprisingly, applicants have discovered that these compounds improve cohesion and adhesion characteristics of a single, self-contained imaging layer contained in a sealed imaging system. The effectiveness of these adhesion promoters can be enhanced by the synergistic combination of the different classes. Representative examples of commercially available compounds useful as adhesion promoters in the present invention include: Blankophor (BAYER), Fluolite (ICI), Hostalux (HOECHST), Leuckopur, Tinopal, Uvitex (CIBA), and whitefluor (SUMITOMO CHEM., Jpn.).
Various polymers may be applied as the subbing layer 11 between the first transparent support 10 and the imaging layer 12. The subbing layer may be applied in a coat weight of about 0.4 to 4 g/m2 (dry weight). Useful polymers include polyethylene oxide and, more particularly, AQUAZOL, and hydroxy containing polymers which can bond to the microcapsules such as partially hydrolyzed polyesters and sulfonated polyesters of aromatic acids and aliphatic or cycloaliphatic alcohols and salts thereof such as the AQ polymers available from Eastman Chemical, e.g., AQ38 and AQ55.
Adhesive materials useful in the adhesive layer 18 in the present invention must generally provide high initial adhesion and adhesion to plastic substrates like polyester. One adhesive useful in the present invention is an aqueous-based adhesive such as Aerosett 2177 or Aerosett 2550 both of which are commercially available from Ashland Chemical Co.; PD 0681, AP 6903, and W 3320 available from H.B. Fuller, or a solvent-based adhesive such as PS 508 sold by Ashland Chemical Co. or an acrylic solvent based pressure sensitive adhesive such as 300 adhesive from 3M Corp. The adhesives may be used separately or in combination. Preferably, the adhesive is transparent or translucent and most preferably it is a transparent aqueous-based adhesive which remains clear even after subjecting the assembly to radiation and pressure necessary to image-wise expose and rupture the microcapsules. The amount of the adhesive will vary depending upon the nature of the adhesive and the support. The adhesive is generally applied in an amount of about 0.5 to 20 g/m2.
The peripheral edges of the self-contained assembly can be bonded using any of the conventional means used to seal polymeric materials such as polyethylene terephthalate. For example, films can be sealed using an adhesive or they may be heat sealed together or they can be sealed by any other technique. Preferably, the PET is sealed using a heat sealing method such as a heat knife. While the seal is described as being at the periphery, it will be appreciated that the seal can be inset from the periphery, e.g., by the distance of a border, provided that the seal is interposed between the imaging chemicals and the users.
In accordance with one embodiment of the invention, a full color imaging system is provided in which the microcapsules are in three sets respectively containing cyan, magenta and yellow color formers respectively sensitive to red, green, and blue light respectively. However, digital imaging systems do not require the use of visible light and as such, sensitivity can be extended into the UV and IR. For optimum color balance, the visible-sensitive microcapsules are sensitive (xcexmax) at about 450 nm, 540 nm, and 650 mn, respectively. Such a system is useful with visible light sources in direct transmission or reflection imaging. Such a material is useful in making contact prints, projected prints of color photographic slides, or in digital printing. They are also useful in electronic imaging using lasers or pencil light sources of appropriate wavelengths.
The photohardenable composition in at least one and possibly all three sets of microcapsules can be sensitized by a cationic dye-borate complex as described in U.S. Pat. No. 4,772,541. Because the cationic dye-borate anion complexes absorb at wavelengths greater than 400 nm, they are colored and the unexposed dye complex present in the microcapsules in the non-image areas can cause undesired coloration in the background area of the final picture. Typically, the mixture of microcapsules is greenish and can give the background areas a greenish tint. Means for preventing or reducing undesired coloration in the background as well as the developed image include reducing the amount of photoinitiator used and adjusting the relative amounts of cyan, magenta and yellow microcapsules as shown in the example which follows. In this regard it is desirable to include a disulfide compound in the photosensitive composition to reduce the amount of dye-borate that may be required as described in detail in U.S. Pat. No. 5,783,353.
The photohardenable compositions of the present invention can be encapsulated in various wall formers using techniques known in the area of carbonless paper including coacervation, interfacial polymerization, polymerization of one or more monomers in an oil, as well as various melting, dispersing, and cooling methods. To achieve maximum sensitivities, it is important that an encapsulation technique be used which provides high quality capsules which can be differentially ruptured based upon changes in the internal phase viscosity. Because the dye-borate tends to be acid sensitive, encapsulation procedures conducted at higher pH (e.g., greater than about 6) are preferred.
Melamine-formaldehyde capsules are particularly useful. It is desirable in the present invention to provide a pre-wall in the preparation of the microcapsules. See U.S. Pat. No. 4,962,010 for a particularly preferred encapsulation using pectin and sulfonated polystyrene as system modifiers. The formation of pre-walls is known, however, the use of larger amounts of the polyisocyanate precursor is desired. A capsule size should be selected which minimizes light attenuation. The mean diameter of the capsules used in this invention typically ranges from approximately 1 to 25 microns. As a general rule, image resolution improves as the capsule size decreases. Technically, however, the capsules can range in size from one or more microns up to the point where they become visible to the human eye.
The developer materials and coating compositions containing the same conventionally employed in carbonless paper technology are useful in the present invention. Illustrative examples are clay minerals such as acid clay, active clay, attapulgite, etc.; organic acids such as tannic acid, gallic acid, propyl gallate, etc.; acid polymers such as phenol-formaldehyde resins, phenol acetylene condensation resins, condensates between an organic carboxylic acid having at least one hydroxy group and formaldehyde, etc.; metal salts of aromatic carboxylic acids or derivatives thereof such as zinc salicylate, tin salicylate, zinc 2-hydroxy napththoate, zinc 3,5 di-tert butyl salicylate, zinc 3,5-di-(a-methylbenzyl) salicylate, oil soluble metals salts or phenol-formaldehyde novolak resins (e.g., see U.S. Pat. Nos. 3,672,935 and 3,732,120) such as zinc modified oil soluble phenol-formaldehyde resin as disclosed in U.S. Pat. No. 3,732,120, zinc carbonate etc. and mixtures thereof. The preferred developer material is one which will permit room temperature development such as zinc salicylate and particularly a mixture of zinc salicylate with a phenol formaldehyde resin. Especially preferred for use is a mixture of zinc salicylate or a zinc salicylate derivative and phenol-formaldehyde resin and, more particularly, a mixture of 25% HRJ 11177, a phenolic resin from Schenectady Chemical Company and 75% zinc salicylate. The particle size of the developer material is important to obtain a high quality image. The developer particles should be in the range of about 0.2 to 3 microns and, preferably in the range of about 0.5 to 1.5 microns.
A preferred developer material is one which has excellent compatibility with the microcapsule slurry solution. Many materials, including zinc salicylate and some phenolic resin preparations, have marginal or poor compatibility with the MF microcapsule preparation and result in agglomeration which is belived to be due to an incompatibility in the emulsifiers used in preparing the microcapsules and in the developer. The problem manifests itself in increasing solution viscosities or in instability of the microcapsules wall (or both). The microcapsules may become completely disrupted with a complete breakdown or disintegration of the wall. The problem is believed to be caused by the presence of water soluble acid salts in the developer solution. By modifying the acidic salts to make them water insoluble the developer material becomes compatible with the MF microcapsules. Examples of preferred developers which have good stability with MF microcapsules include HRJ-4250 and HRJ-4542 available from Schenectady International.
A suitable binder such as polyethylene oxide, polyvinyl alcohol (PVA), polyacrylamide, acrylic latices, neoprene emulsions, polystyrene emulsions and nitrile emulsions, etc. may be mixed with the developer and the microcapsules, typically in an amount of about 1 to 8% by weight, to prepare a coating composition.
The use of appropriate dispersing agents can enhance the adhesion performance of the adhesion promoters of the present invention. This synergistic effect is particularly evident when the dispersing agents are used in conjunction with phenylcoumarin adhesion promoters. Materials that can be used as dispersants in the present invention include partially and fully hydrolyzed polyvinyl alcohol, polyacrylic acid and sodium salts thereof, polyacrylates, and metal salts of condensed arylsulphonic acids. Representative examples of commercially available dispersants useful in the present invention include Rhoplex, Acumer, and Tamol available from Rohm and Haas, Acronal available from BASF and Joncryl available from Johnson Wax.
The dispersant concentration in the imaging system of the present invention can be varied over a wide range, with the upper limit being determined only by economical and practical considerations based on what properties are desired in the final product. It is preferred that the upper limit be about 10%, more preferably 8%, and most preferably about 5%, by weight of the developer resin. The preferred lower limit is about 0.5%. A more preferred lower limit is about 1.0%, with about 1.5% by weight, based on the total weight of the developer resin, being the most preferred lower limit. The dispersant of the invention is an optional additive and can be used either alone or in combination with other dispersants.
Fillers may be incorporated into the imaging layer of the present invention to improve further the cohesive strength of the coating layer and hence the overall binding capability of the layer within the PET substrates is increased tremendously. Such additives include oxides, carbonates and sulfates of metals such as calcium, aluminum, barium, silicon, magnesium, sodium and mixtures of said oxides, carbonates and sulfates, such as tricalcium aluminate hexahydrate, sodium aluminosilicate, aluminum silicate, calcium silicate, barium sulfates (barytes), clays, talc, micas, and mixtures thereof.
Commercially available fillers useful in the present invention include Diafil 590 (CR Minerals), Ultrex 95 (Engelhard), Opti-white (Burgess Inc.), CaCO3 (OMYA, Inc.), hydrophobic and hydrophilic amorphous silica (Wacker), Zeolex, and Hysafe 310 (Huber Corp.).
Microcapsules useful in practicing the present invention are preferably prepared and blended to form a photohardenable layer as illustrated below. In accordance with the invention, the amount of photoinitiator in the microcapsules has been reduced and the ratio of cyan to magenta and yellow capsules has been adjusted to provide a layer with minimal tint so as not to detract from the whiteness of the background.
The invention is illustrated in more detail by the following non-limiting examples.
Model Laboratory Capsule Preparation
1. Into a 200 ml stainless steel beaker, 110 g water and 4.6 g dry sodium salt of polyvinylbenzenesulfonic acid (VERSA) are weighed.
2. The beaker is clamped in place on a hot plate under an overhead mixer. A six-bladed, 45xc2x0 pitch, turbine impeller is used on the mixer.
3. After thoroughly mixing, 4.0 g pectin (polygalacturonic acid methyl ester) is slowly sifted into the beaker. This mixture is stirred for 2 hours at room temperature (800-1200 rpm).
4. The pH is adjusted to 6.0 with 2% sodium hydroxide.
5. The mixer is turned up to 3000 rpm and the internal phase is added over a period of 10-15 seconds. Emulsification is continued for 10 minutes. Magenta and yellow precursor phases are emulsified at 25xc2x0-30xc2x0 C., Cyan phase is emulsified at 45xc2x0-50xc2x0 C. (oil), 25xc2x0-20-30xc2x0 C. (water).
6. At the start of emulsification, the hot plate is turned up so heating continues during emulsification.
7. After 20 minutes, the mixing speed is reduced to 2000 rpm, and a solution of melamine-formaldehyde prepolymer is slowly added. This prepolymer is prepared by adding 6.5 g formaldehyde solution (37%) to a dispersion of 3.9 g melamine in 44 g water. After stirring at room temperature for 1 hour the pH is adjusted to 8.5 with 5% sodium carbonate and then heated to 62xc2x0 C. until the solution becomes clear (30 minutes).
8. The pH is adjusted to 6.0, using 5% phosphoric acid. The beaker is then covered with foil and placed in a water bath to bring the temperature of the preparation to 75xc2x0 C. When 75xc2x0 C. is reached, the hot plate is adjusted to maintain this temperature for a two hour cure time during which the capsule walls are formed.
9. After curing, mixing speed is reduced to 1800 rpm, formaldehyde scavenger solution (7.7 g urea and 7.0 g water) is added and the solution cured another 40 minutes.
10. After 40 minutes hold time, turn down the mixer rpm to 1100 and adjust the pH to 9.5 using a 20% NaOH solution and then allow to stir at 500 rpm overnight at room temperature.
Three batches of microcapsules are prepared as above for use in a full color imaging sheet using the three internal phase compositions set forth below.
Microcapsules prepared as above can be mixed at different percentage ratios to prepare Cycolor Coating Composition. The ratios can be varied to obtain desired photographic characteristics.
A typical coating composition can be coated on PET support (Melinex) at different dry coat weights.
A typical Cylith composition is:
Different aqueous coating compositions were formulated and coated at 17 g/m2 dry coat weight. These had varying peel strength improvements over the standard coating composition.

Self-contained imaging assembly having improved peel strength