The invention relates to a method for the determination of the immune defence activity of blood by the stimulation of white cells in the whole blood, incubation of the whole blood, separation of the supernatant from the sediment and determination of the activity from the separated supernatant. he invention also relates to a test kit for performing the method and to the use of a suitable blood sampling system, particularly a syringe cylinder for this purpose.

1. Field of the Invention
The invention relates to a method for determining the immune defence activity of blood, a test kit for performing the determination and the use of a medical blood sampling system for the determination.
2. Description of the Prior Art
The immune defence activity of blood is determined in order to establish whether blood-conveying organisms, particularly mammals and humans, suffer from a disorder, particularly a weakness of the immune system. In the hitherto known methods blood samples are separated after removal, after which there is a separate treatment and examination of white blood corpuscles. It has been found that as a result of storage and transportation, which can last up to 24 hours and in particular in summer is associated with an undesired thermal effect, a considerable part of the activity of the white blood corpuscles can be lost. Research has revealed that within an hour some cells lose 50% of their activity.
White and red blood cells are separated, because blood red cells are considered responsible for disturbing the activity determination of the white blood cells. Following separation the white blood cells are stored in a buffer medium in the presence of nutrient salts and vitamins. It has been found that an activity change is also possible in such a nutrient solution.
The problem of the invention is therefore to improve the reliability and handling of such activity determinations.
Some blood cells are immediately suitable for testing. However, most cells must be activated in such a way that their metabolism is transposed, i.e. new genes are activated, which generally takes at least 6 to 8 hours. It has now been found that the reliability and reproducibility of activity determination can be significantly improved if an incubation and in particular stimulation of the blood cells is carried out substantially immediately after blood sampling without there being any separation into white and red blood cells. According to the invention the white blood corpuscles are incubated and optionally stimulated for as long as they are in the whole blood. The blood separates itself during incubation without centrifuging being necessary. The supernatant then contains the mesenger substances cytokines) supplied by the white blood cells and which represent a measure for the activity of the cells and which can e.g. be found and determined by ELISA. The expression cytokines, apart from cytokines in the narrower sense, also covers other messenger substances such as e.g. histamine, prostaglandins, leucotrienes, etc.
Thus, the invention provides a method for determining the immune defence activity of the blood by incubating the blood without prior separation, particularly in conjunction with a stimulation of the white blood cells in the whole blood, separation of the supernatant from the sediment and determination of the activity of the blood cells from the separated supernatant.
In many respects the invention leads to the avoiding of errors.
1. Systematic Errors.
Cells normally react on stimulants, e.g. medicaments, not only in an allergic manner, but also on the combination of the stimulants with proteins (carrier proteins), e.g. albumin or lipoprotein, or in combination with other cells, e.g. antigen-presenting cells (APC). In turn, they have surfaces detectable by receptors. The presence of such costimulating signals is additionally necessary in order to bring about a very precise imaging of the natural activities, also to be expected in vivo, of the cells to be examined. Unlike in the case of cultures with isolated leucocytes, whole blood cultures contain said constituents and signals, so that the reaction of the blood cells, for as long as they are present in the whole blood, corresponds more to the natural conditions than in the isolated state. It has also been found that isolated leucocytes have a much greater reaction on stimulants and medicaments than when contained in whole blood, because in whole blood the stimulants and medicaments are frequently bound to erythrocytes and carrier proteins. As a result of this binding the concentration of the stimulants and medicaments is buffered off, which leads to a more gradual release of the messenger substances delivered by the cells.
2. Elimination of Handling Errors.
As stated above, it has been found that the red blood corpuscles do not disturb the activation of the white blood cells (leucocytes) contrary to what has been standing opinion up to now and instead reflect the conditions such as exist in vivo. However, as a result of the separation of the supernatant following incubation it is possible to ensure in a simple manner that the supernatant is not subsequently influenced by the red blood corpuscles (erythrocytes). This has a favourable effect on the storage or dispatch normally necessary after incubation, in that through the introduction of separation the secretion of cytokines in the supernatant is instantaneously prevented and as a result the cell reactions can be ended at a very clearly defined time.
The invention also makes it possible to establish pharmacological and toxicological effects on the immune system.
In a preferred embodiment, without any prior separation, the whole blood is mixed in extracorporeal manner with a blood clotting agent and preferably at least one stimulant (activating agent) for stimulating blood cells, all the blood is incubated in order to stimulate the blood cells, the supernatant form is separated from the sediment and the immune defence activity is determined from the supernatant. The term blood clotting agent more particularly means an anticoagulant with the aid of which the blood is prevented from clotting or coagulating during and after sampling. Incubation preferably takes place in the presence of a nutrient medium. Preferably the nutrient medium is brought together with the blood clotting agent, particularly anticoagulant and in particular with the at least one stimulant before mixing takes place with the blood. As a result the nutrient medium is mixed with the blood in a volume ratio of 5:1 to 1:5, particularly 1:1 to 1:2. The nutrient medium can be placed beforehand in the vessel in which incubation and/or culturing is performed. To obtain reproducible results it is important that incubation is carried out at a constant temperature, more particularly at approximately 37xc2x0 C. This can appropriately take place in a heating block, which preferably has several reception openings for incubation vessels. Besides using heating blocks, the invention also covers the use of other thermostatically controllable devices. Thus, incubation can also take place in a water bath or e.g. in a corresponding thermostatically controlled cabinet or the like. The incubation period can be a few minutes to approximately 60 hours and is in particular between 8 and 60 hours. The appropriate incubation period is 24 or 48 hours. This also aids the acquisition of reproducible values. During the incubation period the red and white blood corpuscles normally automatically settle. The separation of the supernatant from the blood corpuscles is consequently advantageously carried out without prior centrifuging. Particularly with short incubation periods, it can also be advantageous to carry out centrifuging for the sedimentation of the solid constituents of the blood. The activity can be determined on the supernatant by determining the messenger substances (cytokines) separated from the blood cells. Determination more particularly takes place in per se known manner by ELISA or other suitable testing methods.
Generally the whole blood is incubated in the presence of at least one stimulant. However, working can also take place without stimulants, e.g. if it is to be established to what extent the cells are already prestimulated in the body.
Generally activity determination takes place at a different location to the incubation, or for other reasons activity determination does not take place directly after the end of incubation. Thus, it is advantageous according to the invention to store in cooled state the supernatant until activity determination takes place, particularly at temperatures of 0 to 8xc2x0 C., more especially at approximately 4xc2x0 C. Freezing is also possible in special cases. As the supernatant and also preferably the settled blood corpuscles remain in the incubation vessel after separation, the sediment is cooled with the blood corpuscles. It is particularly preferred for the blood sampling system used for sampling purposes to be used also as an incubation vessel. Preferably a conventional syringe cylinder is used as the blood sampling system. However, the invention also covers other blood sampling systems, such as e.g. evacuated glass tubes with a rubber seal on which can be fitted cannulas. The separation of the supernatant from the blood corpuscles is preferably performed in the blood sampling system, particularly with the aid of a temporarily permeable membrane or partition. For this purpose it is particularly advantageous to have a plunger displaceable in the blood sampling system. The blood sampling system used for blood sampling purposes can also be advantageously used, following the separation of the supernatant and blood corpuscles, as a cooling, transportation and in particular dispatch container. Dispatch can take place in so-called cooling or refrigerating blocks, which are filled with a cold storage medium and preferably have a blind hole serving as an insertion opening for receiving the blood sampling system, particularly the syringe cylinder.
The syringe cylinder for performing the method according to the invention can with particular advantage be in the form of the syringe cylinder with the break-off piston rod and a cap on the side of the needle freeing the entire cylinder cross-section commercially available under the name Monovette (registered trademark of Sarstedt). Such syringe cylinders can be handled in the same way as test tubes or centrifuge tubes after breaking off the piston rod. After the incubation period and the settling of the blood corpuscles, a plunger associated with the syringe cylinder can be inserted from above with the cap removed and pressed into the supernatant, which flows through the plunger and at the end of the pressing-in process and the extraction of a press-in rod closes of its own accord, so that subsequently a mixing of the blood corpuscles and supernatant cannot take place. The blood corpuscles trapped in the lower part of the syringe cylinder and the supernatant separated therefrom and located in the upper part are left in the syringe cylinder during further handling until the supernatant is removed for carrying out the activity determination. Syringe cylinders are commercially available which, for blood sampling purposes, contain an anticoagulant, e.g. heparin, particularly in lyophilized form. Such syringe cylinders usually also contain plastic beads in order to bring about a rapid separation of the red corpuscles from the supernatant. In the case of the method according to the invention the syringe cylinder preferably also contains an anticoagulant, but not the normally present plastic beads. Advantageously, in the method according to the invention, the syringe cylinder also contains at least one stimulator, preferably also in dry, particularly lyophilized form. However, it is also possible to separately store the at least one stimulator, e.g. in the form of a stabilized solution and to place it separately in the syringe cylinder, particularly shortly before blood sampling. Prior to blood sampling the desired nutrient medium volume can be introduced into the sydringe cylinder, particularly by suction from a perforating blood. During blood sampling there is then an immediate mixing with the nutrient medium in which also the previously introduced substances are dissolved.
In a further preferred embodiment of the invention at the time of blood sampling the blood sampling system exclusively contains the blood clotting agent, particularly the anticoagulant. This embodiment avoids the risk of an accidental reinjection of the content of the blood sampling system (e.g. stimulants and/or nutrient medium) into the person, where damage may be caused. After blood sampling, in this embodiment, the further additives, such as e.g. stimulants and/or nutrient medium, are added to the blood in the blood sampling system. This can in particular take place by suction from corresponding perforating bottles.
Stimulants can be used alone or combined with one another. Stimulants which can be used are in particular mitogens, which are substances activating cell division. Numerous different types exist and are inter alia used for activating the different subtypes of lymphocytes. There are also particulate activators of granulocytes and monocytes, such as zymosan and bacteria. Granulocytes and monocytes can also be activated by soluble signal substances such as LPS and muramyl peptides. It is also possible to use antigens and allergens, as well as antibodies against surface structures of the cells, in order to stimulate in preferred manner selectively determined cells.
Th2-lymphocytes have a particularly good combined activating action, i.e. using several stimulators. Mitogen and/or phorbol esters combined with antibodies, e.g. anti-CD 28 are suitable. The latter is a costimulating coactivator. Iio channel-forming ion charging agents are also suitable. If the stimulators release competing mediators, e.g. interleukin 4 and interferon gamma from T-cells, then preferably at least two different batches are used. This is particularly important when examining the blood of allergic and atopic subjects, such as those with neurodermatitis, where too much interleukin 4 is formed. The large number of activity determinations which can be performed is illustrated by this non-exhaustive list. It is consequently possible to keep in stock the blood sampling systems, particularly syringe pistons for blood sampling adapted to the particular determination types and which already can contain the specific stimulants in each case.
The invention consequently also relates to test kits for the determination of the immune defence activity of blood cells and which comprise
a) blood sampling instruments with
b) a blood sampling system, particularly a syringe cylinder for blood sampling,
c) an anticoagulant, which is preferably stored in lyophilized form in the blood sampling system, particularly in the syringe cylinder,
d) optionally at least one stimulant for activating the blood cells and which is preferably stored in dried, particularly lyophilized form in the blood sampling system, particularly in the syringe cylinder, or in a separate vessel,
e) a culture solution for culturing the sampled blood and
f) a plunger fitting into the blood sampling system, particularly the syringe cylinder, for the separation of settled, red blood corpuscles from the supernatant in the blood sampling system.
The culture solution is preferably stored in a perforating bottle, the volume of the latter preferably corresponding to the nutrient solution volume suitable for culturing. Through a complete emptying of the storage bottle before or after blood sampling, the correct volume is transferred into the blood sampling system, particularly into the syringe cylinder. Generally the plunger is located outside the blood sampling system and following the settling of the blood corpuscles and following the end of incubation can be introduced into the blood sampling system, particularly the syringe cylinder.
The equipment preferably also includes an aforementioned, thermostatically regulatable device, particularly a heating block, into which can be inserted the blood sampling systems, particularly syringe cylinders, e.g. 20 such cylinders simultaneously, which makes it possible to simultaneously culture several batches. The equipment also includes a suitable cooling device and an adequate number of cooling blocks for transportation. If desired or if special determinations have to be performed, it is also possible to use empty blood sampling systems or those only containing individual substances and then to add to them the substances desired for the special case, such as e.g. combinations of stimulators.
Lyophilized heparin and opsonized zymosan as a possible stimulant are placed in a syringe cylinder, e.g. a Sarstedt Monovette. On the syringe cylinder is mounted the associated needle, after which the entire content of a solution of approximately 3 ml is sucked out of a perforating bottle. The blood clotting agent and stimulant are received in the nutrient medium. From the person whose blood is to be examined is then removed 2 ml of blood, which can place within the framework of multiple examinations. The blood removed is mixed with the culture solution and the substances contained therein. After the removal of the syringe needle the syringe piston remains sealed, because a screw cap provided thereon has a self-sealing perforating membrane. When the syringe piston is drawn downwards, the piston rod is broken off by lateral bending away at a predetermined breaking point, so that the syringe piston is usable in the manner of a test tube with closure. The syringe piston is then placed in a heating block together with other syringe pistons, where similar tests are performed and in the same incubation takes place at a constant 37xc2x0 C. for 24 hours. During this time the cells are stimulated for the delivery of their messenger substances, which are delivered to the serum. During incubation the blood corpuscles settle on the bottom, so that a substantially clear supernatant is left behind. At the end of the incubation period the syringe cylinders are removed from the heating block and opened by removing the cap. With the aid of a ram a plunger, whose external diameter corresponds to the internal diameter of the syringe cylinder, is introduced into the latter and is slowly pressed by the supernatant to just above the sedimented blood corpuscles in the liquid, the valve in the plunge opening and giving rise to a flow of the supernatant into a separate space formed above the plunger. After removing the ram used for this, there is an automatic closure of the valve in the plunger and the syringe cylinder can be resealed by fitting the screw cap. In this way the blood corpuscles are permanently separated from the supernatant, independently of any vibrations to which the syringe piston is exposed thereafter. After the separation of the blood corpuscles and supernatant, the syringe pistons are cooled to a temperature of approximately +4xc2x0 C. and inserted in cooling blocks, which are also cooled to this temperature or a temperature below it. The cooling capacity of these cooling blocks is dimensioned in such a way that they maintain their temperature in dispatch bags, e.g. air cushion bags, for a dispatch period of at least 24 hours without any risk of an undesired temperature rise. In the test laboratory, which is generally at a location different from that where blood sampling and incubation took place, the activity determination can be performed e.g. by ELISA, using predetermined supernatant volumes. Parallel tests have revealed that in this procedure precise, reproducible activity values are obtained.

Method for determining the immune defense of blood and test kit for the same and use of a suitable blood sampling system

EDI (Experimentelle and Diagnostische Immunologie) GmbH


The invention provides a waveguide type liquid crystal optical switch that includes first and second cores so as to form a space therebetween, in which an optical path is switched between the first and second cores; a third core provided apart from the first and second cores, into which nematic liquid crystal orientated by an orientation film along a predetermined direction is filled, the third core overlapping to the space formed between the first and second cores; a first electrode arranged on an opposite side of the first and second cores with respect to the third core so as to overlap to the space between the first and second cores, second and third electrodes arranged on both sides of the first electrode, for orienting liquid crystal molecules along a direction perpendicular to the orientation direction of the orientation film; and a cladding for incorporating the cores and the electrodes.

The present application is based on Japanese Patent Application No. 2002-143335, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention is related to an optical switch employed in, for instance, optical communication systems. More specifically, the present invention is directed to a waveguide type liquid crystal optical switch for controlling switching operations of optical paths between waveguides by way of liquid crystal.
2. Related Art
Since large amounts of information can be transmitted/received in optical communications, very recently, these optical communications are gradually popularized in many homes. These optical communications correspond to transmission systems by employing optical fibers. In order to distribute optical signals to respective terminals of such transmission systems, various sorts of optical components known as fiber type optical couplers, optical wavelength division multiplexers/demultiplexers optical wave guide type branching/combining devices, and optical switches have been developed.
Among these optical components, optical switches may have switching functions of optical paths, and thus, may become important as switching devices for optical communications. Conventionally, various sorts of optical switches utilized in optical communications are known in this technical field. Among these optical switches, since such an optical switching system that while optical waveguides are used, optical transmission paths are switched by utilizing various sorts of physical phenomena is not equipped with any mechanical movable portion, this optical switching system has merits of high reliability and highspeed operations. As such an optical switching system, for instance, various optical switches are known. That is, there are optical switches using dielectric crystal waveguides such as LiNbO3 having either the electrooptic effect or the acostooptic effect; optical switches using semiconductor waveguides, while carrier injection is utilized; and optical switches using silica-system waveguides, while the thermooptic effect is utilized.
Also, among optical switches equipped with similar optical waveguides, optical switches using liquid crystal are known. Liquid crystal may have the electrooptic effect under which refractive indexes are changed by applying electric field to the liquid crystal, in view of abroad sense Also, liquid crystal may have various characteristics, namely, liquid crystal may be driven under low voltages, may have high reliability (actually realized as display devices), may have high productivity, and may be manufactured in low cost. As such optical wavelength type liquid crystal switches, for example, Japanese Unexamined Patent Publication No. H05-165068A describes such a waveguide type liquid crystal optical switch constituted in such a manner that two parallel single-mode optical core patterns are formed on the lower cladding and are equipped with the coupling portions, the partial portions of which are located in close proximity to each other; and furthermore, the lower electrode is formed on the lower cladding of the coupling portions, the coupling portions are filled with the orientated liquid crystal; and the coupling portions are sealed by the glass plate having the upper electrode.
However, in this waveguide type liquid crystal optical switch, since both the liquid crystal and the electrodes are formed in such a manner that the substantially entire portion of the lower cladding is covered, the refractive indexes are changed over the wide range of the lower cladding, so that the guided mode may be disturbed, and large crosstalks happen to occur. Such large crosstalks may cause a fatal defect with respect to optical switches. Moreover, since the three planes of the coupling portion of the waveguide core are made in contact to the liquid crystal, if there are such liquid crystal molecules which are not orientated along the predetermined direction, then the scattering loss caused by these not-orientated liquid crystal molecules is accordingly increased. Also, the lower electrode is located very close to the coupling portion of the waveguide, so that the loss caused by this lower electrode becomes very large. In addition, since this waveguide type liquid crystal optical switch has such a construction that only one pair of upper/lower electrodes are limitedly arranged, this optical switch has another problem that the polarized-wave dependent characteristics thereof are strongly emphasized.
The present invention has been made to solve these problems of the conventional optical switch, and therefore, has an object to provide a waveguide type liquid crystal optical switch capable of improving crosstalk performance and insertion loss and further having no polarized-wave dependent characteristic in addition to tho merits specific to such a waveguide type liquid crystal optical switch, namely, low cost, high reliability, and low power consumption.
To achieve the above-described object, a waveguide type liquid crystal optical switch, according to the present invention, is featured by that in an optical switch equipped with an optical waveguide having one pair of a first core and a second core located in proximity to the first core, for entering light into any one of the first core and the second core and for switching an optical path of the entered light between both the first core and the second core, such a waveguide type liquid crystal optical switch is comprised of: a third core provided apart from both the first core and the second core in such a manner that the third core covers a space sandwiched by both the first core and the second core, into which nematic liquid crystal orientated by an orientation film along a predetermined direction is filled; a first electrode of the third core, arranged on the opposite side with respect to both the first core and the second core in such a manner that a gap portion between the first core and the second core is covered by the first electrode; a second electrode and a third electrode, which are arranged to constitute a pair by sandwiching the first electrode, and cause liquid crystal molecules to be orientated along a direction perpendicular to the orientation direction of the orientation film; and a cladding for incorporating the first core, the second core, the third core, and the first to third electrodes.

Waveguide type liquid crystal optical switch


The present invention concerns a jewelry clasp, for use with necklaces, bracelets and other chain jewelry. The clasp comprises a receptacle, having two parts with a plurality of anchors attached to the inside surfaces of the receptacle. The receptacle may be opened to allow the attachment of chains within the box and then closed and locked to secure the chains. The anchors allow the holding of the ends of a number of pieces of chain jewelry by the clasp. The ends of various pieces of chain jewelry may be attached to any number of the anchors to form new configurations of jewelry. The receptacle may be made to appear decorative so that, if desired, the clasp may be large to facilitate its use and to allow for any number of chain anchors so that the user may attach any number of jewelry chains in a decorative manner.

The present invention concerns a novel jewelry clasp that allows chain based pieces of jewelry to be combined together to form a number of different types of jewelry.
The use of chains as jewelry to hold precious stones, semi-precious stones, pearls, medals and other ornamentation has been one of the most popular forms of personal decoration in history. Chains have been used as necklaces and bracelets, to hold prayer beads, worry beads and pocket watches and as other forms of jewelry.
Chain based jewelry generally is provided with a clasp that connects the ends of a chain together to form a necklace, bracelet or other form of jewelry. In the past, the clasp of such jewelry allowed the jewelry to be worn only for the function for which it was designed. A necklace chain could only be worn as a necklace and a bracelet could only be worn as a bracelet. Further, these clasps have generally been designed to allow the connection of one end of a chain to the other, so that no variation of jewelry could be made. The clasps of these chains generally comprises some variation of male and female pieces, one on each end of a chain, that mechanically fit together to form a necklace or bracelet. Such items as a hook and eye, spring catch and ring, or bolt ring and ring, are common means used to form chain jewelry. These clasps are generally made so as to blend in with the chain so that the clasp will not be noticed.
Jewelry clasp are generally utilitarian device that when worn are worn out of sight, usually behind the neck or on the underside of the wrist, and therefore need not be aesthetically pleasing. Generally, a clasp has not been considered as part of the jewelry, but instead, has been considered as merely a means to fasten the ends of a chain together to form the jewelry. Because of this, and so as to allow the clasp to blend in with the chain, clasps have generally been made very small.
Because of their small size clasps generally cannot be made very strong and often times they will break causing the loss of the jewelry, or the suffering of expensive repair bills. Further, because clasps are made small, they are often difficult to see and can be difficult, particularly for older persons or those with disabilities such as arthritis, to manipulate. Often times, as a result of the size of the clasp, a piece of jewelry is not worn because the clasp is too difficult to use. Also, jewelry has been lost because it had been thought that the clasp was secure when, because of its small size, it could not be seen that it had not been secured.
We have invented a new type of clasp that allows for variations in the manner that jewelry is secured so that for example a bracelet may be reconfigured to be worn as a part of a necklace or an additional piece of jewelry may be added to a necklace or bracelet to change the character of the jewelry or form a unique piece of jewelry. Our clasp can be made relatively large, and yet remain decorative, so that the user can easily manipulate the clasp, check the clasp for security and wear the clasp as part of the jewelry. Further, our clasp allows the user to combine various pieces of chain jewelry together to make new jewelry configurations. Our clasp also allows the addition of pendants, fobs and other jewelry items to make new necklaces, bracelets and other jewelry combinations. In one embodiment of our clasp, we have increased the size of the clasp and made it decorative so that different combinations of jewelry may be made and the clasp may be included as a decorative aspect of the jewelry combination. We have also found that our clasp may be used to replace the clasp originally provided with a piece of chain jewelry, thus either effecting a quick repair or making the jewelry more fashionable by the addition of a decorative clasp.
It is therefore an object of the present invention to provide a jewelry clasp that can be used to reconfigure existing jewelry into new jewelry pieces.
It is another object of the present invention to provide a decorative jewelry clasp that may be made large so that use of the clasp is facilitated.
It is a further object of the present invention to provide a jewelry clasp that is easy to open and close and is strong and durable.
It is a further object to provide a clasp that forms part of the decoration of the jewelry and which can be worn so that reaching the clasp for manipulation, attachment or removal, of the jewelry is made convenient to the wearer.
It is a further object of the present invention to provide a jewelry clasp that allows the connection of multiple jewelry chains, pendants, fobs or other pieces of jewelry to allow the user to manipulate such individual pieces of jewelry together to arrive at new jewelry combinations.
Other objects and advantages of the present invention will become apparent as the description proceeds.
In accordance with the present invention, a jewelry clasp, for use with jewelry chains is provided. The clasp comprises a receptacle having a first portion and a second portion connected to each other. A plurality of anchors are defined in the interior walls of the first and second portions of the receptacle for holding the ends of jewelry chains, such that the jewelry chains may be manipulated, within the clasp, to form a plurality of jewelry configurations.
In the illustrative embodiments, the clasp is generally a hollow box divided into two portions; the portions being rotatably connected to each other by a hinge and being lockable together by conventional means. In the preferred embodiment the second portion comprises a lid and the first portion comprises the remainder of the box. On the inside wall of the second portion of the box, two anchor points, comprising hooks attached to the inner wall of the box, are provided. On the inside wall of the first portion, a single anchor is provided. In the illustrative embodiments, the two hooks on the second portion of the box have their connection points disposed downwardly so that the clasp may be suspended from a chain attached to the two anchor points. The hook on the first portion of the box has its connection point disposed upwardly so that a pendant, or other object, may be suspended from the clasp when the Jewelry is worn.
In the preferred embodiment, the top of the clasp defines openings which allow the two ends of a chain to be anchored within the clasp and emerge from the clasp. The bottom of the clasp defines an opening allowing a pendant, or another chain, to be attached within the clasp and emerge from the clasp. In the illustrative embodiments, when the clasp is in the closed position, the ends of the chain and pendant are inaccessible and the chain and pendant are secured.
In the preferred embodiment, the clasp has been designed in a generally kidney shaped form for decorative purposes. It is to be understood that the clasp may take any decorative form, such as circular, rectangular or heart-shaped, without departing from the novel scope of the present invention.
In the preferred embodiment of the present invention, three anchors, as described above, are provided and are placed so that when the clasp is in the closed position, the anchors are in a triangular relationship. In this way the anchors do not touch each other and there is room for chains to be attached to each without becoming entangled.
In the illustrative embodiments of the invention, a hasp-like device is provided on one portion of the clasp and a knob is provided on the other portion, such that when the first and second portion of the receptacle are rotated together, the clasp may be locked to secure the jewelry chains within the box. It is to be understood, however, that any form of locking device or jewelry safety catch may be provided without departing from the novel scope of the present invention. It is to be further understood that the hinge described above may be replaced by another hasp and knob, or other locking means, and that the first and second portions of the clasp may be separate pieces that may be fit together and locked in two places.
The illustrative embodiments include a method of wearing a necklace, using the clasp of the present invention, such that the clasp is worn on the chest in a decorative manner. In this way, the clasp acts as a decoration, while allowing the wearer easy access so that the chains may be manipulated, the jewelry may be easily secured, and later, when desired, removed.
A more detailed explanation of the invention is provided in the following description and claims and is illustrated in the accompanying drawings.


Powder coating formulations include as a component thereof a silane formula I:

This invention pertains to powder coating and adhesive formulations utilizing organosilane compounds, or their hydrolyzates or condensates, as crosslinkers and/or adhesion promoters.
Powder coatings are an environmentally friendly system, making them a desirable alternative to conventional solvent borne coating systems. Overall, operating and material costs are such that powder coating competes favorably with the solvent and waterborne markets.
Although powder coating represent only a portion of the total market, as compared to solvent type systems, the technology has considerable advantages. Most notably, since powder coating lacks solvent, there are no VOC issues with which to be concerned. Further, since there is less waste generated, the powder coating technique has less impact on the environment.
Powder coating involves several steps, the most critical of which is the premixing of the ingredients. During this initial phase, the binder, together with the other additives are mixed thoroughly in the equipment. Inadequate premix in the first stage could lead to a non-homogenous composition of the coating and poor mechanical properties or surface defects in the final product. The resulting premix is then fed into an extruder. The molten material produced from the extruder is cooled and squeezed into easily breakable strips. The strips are then ready for grinding to a particular particle size range.
The most common method for the application of powder coatings is by electrostatic spraying. The basic principle of this method involves propelling the powder, via compressed air, through a spray gun where it becomes electrostatically charged. In addition to charging the powder the gun also serves to deposit the powder supplied by the feeder. When the electric field is removed, the charged particles are still held on the surface, attracted by charges on the substrate. The uncharged powder in the overspray is collected and reused.
Another commonly used method of powder coating is triboelectric spraying. This is similar to electrostatic spraying, except the particles are positively charged (electrostatically charged particles have a negative charge). A new technique, that is being developed for flat surfaces, employs electromagnetic brush technology which enables efficient high speed application of very thin layers with no recycling.
Among the drawbacks of thermoset powder coating systems is the difficulty in making tough films from ingredients that are low in molecular weight and therefore able to flow easily under shear conditions. Since the application of the powder coating involves overspraying, specialized recovery equipment is also necessary to reclaim the unused powder. Substrates must also be able to withstand the powder coating cure temperatures which typically range between 150 and 190xc2x0 C.
The silanes of the present invention advantageously can be used to improve the physical and chemical properties of thermoplastic powder coatings. These powder coating formulations do not require curing agents and can be applied via the aforementioned electrostatic or tribostatic spray techniques. However, most thermoplastic powder is applied by passing the heated substrate through a fluidized bed.
Silanes are known to be useful in liquid coatings. For example in WO 96/39468 sprayable liquid coating compositions are described which include a film-forming reactive silyl group-containing compound and polymer microparticles insoluble in the liquid coating composition.
One aspect of the invention is a powder coating formulation which includes as a component thereof a silane of the formula:
where R1 is a hydrocarbon, acyl, alkylsilyl or alkoxysilyl group; R2 is a monovalent hydrocarbon group; R3 is alkylene, optionally interrupted with one or more ether oxygen atoms; a is 0 or 1; Z is a direct bond or a divalent organic linking group; X is an m-valent organic group or H; and m is 1 to 20.
Silanes, useful in the present invention, can be prepared via many synthetic routes. For instance, a terminally unsaturated organic compound can be hydrosilylated to give a silane. Further chemical reactions can be carried out on silanes having organo functional groups. Silyl carbamates, useful in the invention can be prepared by reaction of polyol compounds with isocyanatopolyalkoxysilanes. Other carbamates, useful in the invention can be prepared by reaction of polyisocyanates with hydroxyalkylpolyalkoxy silanes. Such silyl carbamates can also be made by reaction of a polyisocyanate with a terminally unsaturated alcohol, and subsequent hydrosilation. Silyl isocyanates can be oligomerized to: uretdiones, allophanates, biurets, isocyanurates. Silyl amines can be reacted with anhydrides to yield amides or with isocyanates to yield ureas.
Powder coatings within the invention may be based on a conventional resin system, in such coatings the silane component of formula I function as property modifying and/or crosslinking additives. Silane compounds of formula I, where m is greater than 1, and especially those in which X is polymeric, may be used as the base crosslinking resin for the coating formulation.
Powder coating systems may be based on a number of thermosetting chemistries. Well known powder coating systems include polyurethane systems based on blocked polyisocyanates and polyols, especially polyester or poly(meth)acrylate polyols; acid functional acrylic or other acid functional polymers cured with epoxy functional curing agents; anhydride/epoxy systems; epoxy/polyol systems; hybrid systems employing epoxide resins and polyesters with both carboxyl and hydroxyl functionality; systems based on hydroxyalkylamides and acid functional polymers. Examples of suitable epoxy resins include bisphenol A-type polyepoxides, glycidyl methacrylate copolymers and epoxy-novolac resins. Typically the systems are designed to melt-flow and to cure concurrently in a single heating step, although in some cases a UV curing system may be employed to separate the film-forming melt flow stage from the curing stage.
Particular powder coating systems in which the inventive compounds are useful include polyester-urethane powder coatings in which hydroxyl-functional polyester resins are cured with polyisocyanates. The polyisocyanates are blocked internally or blocked with a blocking agent. The leading blocking agent is xcex5-caprolactam. When the powder-coated part is heated, xcex5-caprolactam, is volatilized, unblocking the isocyanates groups and leaving them free to react with the hydroxyl functionality on the polyester resin. The most common blocked isocyanate is the caprolactam-blocked IPDI (isophoronediisocyanate) such as Hxc3xcls Vestagon B1530. The polyisocyanates can be blocked internally by a dimerization process to form uretidone. One such uretidone compound that is commercially available is Hxc3xcls Vestagon BF 1540 (an IPDI uretidone).
Typical hydroxyl-functional polyester resins used in polyester-polyurethane systems are derived from condensation polymerization of glycol, dicarboxylic acid and polyol (more than two hydroxyl groups in the monomer). Frequently used glycols are trimethylpentanediol and neopentyl glycol; polyols include trimethylolpropane and trimethylolethane. Dibasic acids include isophthalic acid and terephthalic acid. A standard method of preparation of hydroxyl-functional polyester resin for polyurethane powder coating with reaction details is given in the book of Oldering and Hayward [Oldering, P., and Hayward, G., in Resins for Surface Coatings, Vol. II, SITA Technology, London, 1987, p.137.]. Different patents describe methods for making hydroxyl functional polyester resin for polyurethane powder coatings with minor variations with respect to the acid value, hydroxyl value, functionality of the resin and the choice of the raw materials. The hydroxyl-functional polyester for powder coatings could have an acid number less than 10, a molecular weight of 2800-3200, a hydroxyl number of 84, and a softening point at 95-100xc2x0 C.
A typical IPDI-crosslinked powder coating formulation is as follows: 52-53% hydroxyl polyester, 12-13% IPDI crosslinker, 34% pigment filler 1% flow modifier and small amount of other ingredients.
Other powder coating systems in which the inventive silane compounds are useful are acrylic-urethane powder coatings. In such systems hydroxyl-functional acrylic resins are used to prepare acrylic-urethane powders in essentially analogous way to polyester-urethanes. The hydroxyl-functional acrylic resins can be prepared as a copolymer of methyl acrylate, styrene, acrylate esters, hydroxyethyl methacrylate and acrylic acid. Typically, about 9-10% of hydroxylethylmethacrylate is needed to yield a resin with a hydroxyl value of 40, and about 2% of acrylic acid to result in acid value of 16. Methyl methacrylate and styrene copolymers yield high Tg (e.g. 95xc2x0 C.-105xc2x0 C.) and are usually flexibilized with longer chain acrylates or methacrylates such as butyl, ethyl, or 2-ethylhexyl. Butyl acrylate often is preferred as an acrylic comonomer because its excellent UV resistance combined with high flexibility. The molecular weight of acrylic copolymer resins are usually 5,000-20,000.
Formulations for acrylic-urethane powder coatings are similar to the polyester-urethane formulations except for the use of the acrylic resin in place of the polyester resin.
Still other powder coating formulations in which the silane compounds of the invention may be employed are based on glycidyl functional acrylic resins (especially glycidyl methacrylate copolymers) and compounds having two or more carboxylic acid groups such as dodecanedioic acid. Exemplary glycidyl methacrylate copolymers are made from 15-35 weight percent glycidyl methacrylate, 5-15 weight percent butyl methacrylate and the balance styrene and/or methyl methacrylate; have a number average molecular weight of below 2,500; have a Tg of above 80xc2x0 C.; and have a melt viscosity of less than 400 poise (40 Pascal seconds) at 150xc2x0 C.
The inventive silane compounds also may be employed in TGIC/polyester powder coating systems. In such systems carboxyl-functional polyester resins are cured with TGIC (triglycidyl isocyanurate). A polyester resin suitable for production of powder coatings with TGIC in the formulation is described in the patent of DSM resins BV [DSM Resins BV, Belg. Pat 898 099, 1982]. The resin is obtained by fusion esterification of neopentyl glycol, 1,4-cyclohexanedimethanol, 1,6-hexane diol, trimethylolpropane, terephthalic acid and adipic acid. Products with average molecular weight between 4,500 and 12,500 with acid values of 10-26 mg KOH/g and Tg of 40-85xc2x0 C. are obtained which are suitable for making powder coatings containing 1.4-5.3% by weight of TGIC. The silanes of the present invention can also be used with similar carboxyl functional polyesters that are cured with hydroxyalkylamides.
The powder coating formulations of the invention may also be based on a thermoplastic polymer such as nylon, polyolefins (for instance polypropylene and polyethylene), polyphenylene sulfide or polyvinylchloride.
The softening points of the base components of the powder coating compositions are such that the necessary additives to produce the coating formulations of the invention can be worked in at temperatures between about 80xc2x0 C. and 140xc2x0 C. and yet produce a composition which can be subsequently extruded and ground to a fine free-flowing powder of about 20-120 micrometer size. Solid additives that melt and are compatible with the formulation are preferred. However, compatible liquids can be utilized via a master-batch or on an inert carrier.
A necessary component in the compositions of the present invention is a polyalkoxy or polyacyloxy silane compound, of formula I:
where R1 is a hydrocarbon, acyl, alkylsilyl or alkoxysilyl group; R2 is a monovalent hydrocarbon group; R3 is alkylene, optionally interrupted with one or more ether oxygen atoms; a is 0 or 1; Z is a direct bond or a divalent organic linking group; X is an m-valent organic group; and m is 1 to 20. The number m is preferably 2 to 6, most preferably 2.
The group R1 may be an alkyl, aryl, alkaryl, aralkyl or acyl group, for instance, methyl, ethyl, n-propyl, isopropyl, butyl, t-butyl, phenyl, benzyl, tolyl, benzoyl, or acetyl. R1 may also be an alkylsilyl group, for instance a trialkylsilyl group such as trimethylsilyl, triethylsilyl or tripropylsilyl or an arylalkyldialkylsilyl group such as benzyldimethylsilyl or tolyldimethylsilyl. R1 may also be an alkoxysilyl group, for instance a trialkoxysilyl group such as trimethoxysilyl, triethoxysilyl and tripropoxysilyl; an alkyldialkoxysilyl such as methyldimethoxysilyl, methyldiethoxysilyl, ethyldimethoxysilyl, ethyldiethoxysilyl, methyldipropoxysilyl and ethyldipropoxysilyl; or dialkylalkoxysilyl such as dimethylmethoxysilyl, dimethylethoxysilyl, dimethylpropoxysilyl, diethylmethoxysilyl, diethylethoxysilyl, and diethylpropoxysilyl. Preferably R1 is a linear, branched or cyclic C1-C6 alkyl group or an acetyl group. Most preferably R1 is ethyl or methyl. Suitable R2 hydrocarbon groups are aryl, alkenyl or alkyl groups, which may be linear, branched or cyclic, especially lower (C1-C4)alkyl groups such as methyl or ethyl. R3 is suitably C2-C12 linear, branched or cyclic alkylene, preferably C2-C6 alkylene. Exemplary R3 groups are propylene, ethylcyclohexylene, 3,3-dimethylbutylene, ethylene and methylene.
Z is a direct bond or a divalent organic linking group. Suitable divalent linking groups include ester, amide, urea, uretdione, carbamate, carbonate, aromatic ring, heterocyclic ring, allophanate, biuret, amine, ether and thioether. The Z groups may be the same or different.
The m-valent organic group X is typically a residue of an organic compound having one or more carboxylic acid, halide, alcohol, isocyanate, amine, epoxy, thiol, or other pendant or terminal functional groups which have been reacted in a known manner to form the linkages Z. The residue X may be polymeric, for instance polyacrylate, polycarbonate, polyurethane, polyalkylene, polyester, polyamide, polyether, and combinations of these. Preferably the group X is an aliphatic, cycloaliphatic or aromatic hydrocarbon group, preferably a C4-C24 hydrocarbon group, especially a saturated linear, branched or cyclic aliphatic hydrocarbon group. Exemplary X groups include 2,3-butylene; 1,6-hexylene; 1,4-cyclohexanedimethylene; 1,4-cyclohexylene; 1,7-heptylene; 1,8-octylene; 1,12-dodecylene; 1,10-decylene; 1,9-nonylene; 4,4xe2x80x2-isopropylidenediphenylene; 4,4xe2x80x2-isopropylidenedicyclohexylene; 1,4-butylene; phenylene; methylphenylene, 1,3-(xcex1,xcex1,xcex1xe2x80x2,xcex1xe2x80x2-tetramethyl)xylylene.
Preferred silanes useful in the inventive formulations may be characterized by formula II:
where R1, R2, R3, a, m and X are as previously defined, and A and B are independently xe2x80x94NHxe2x80x94 or xe2x80x94Oxe2x80x94.
Silyl carbamates of formula II, where A=NH and B=O, may be prepared by reaction of polyol compounds with isocyanatoalkylalkoxysilanes. Novel silane carbamates which may be obtained in this manner include carbamates so formed in which the polyol compound is a hydrocarbon diol. Linearly symmetrical diols such as 1,4-cyclohexanediol, 4,4xe2x80x2-isopropylidenedicyclohexanol and 1,4-cyclohexanedimethanol also produce preferred silane carbamate compounds of the invention. Silyl carbamates of this type can also be made by the reaction of a silyl isocyanate with a polymeric polyol, such as a polyether polyol, a polyester polyol, a polybutadiene polyol or a polyacrylate polyol.
Examples of suitable isocyanatoalkylalkoxysilanes are isocyanatopropyltrimethoxysilane, isocyanatopropylmethyldimethoxysilane, isocyanatopropylmethyldiethoxysilane, isocyanatopropyltriethoxysilane, isocyanatopropyltriisopropoxysilane, isocyanatopropylmethydiisopropoxysilane; isocyanatoneohexyltrimethoxysilane, isocyanatoneohexyldimethoxysilane, isocyanatoneohexydiethoxysilane, isocyanatoneohexyltriethoxysilane, isocyanatoneohexytriisopropoxysilane, isocyanatoneohexyldiisopropoxysilane, isocyanatoisoamyltrimethoxysilane, isocyanatoisoamyldimethoxysilane, isocyanatoisoamylmethyldiethoxysilane, isocyanatoisoamyltriethoxysilane, isocyanatoisoamyltriisopropoxysilane, and isocyanatoisoamylmethyldiisopropoxysilane.
Examples of suitable polyol compounds which will produce solid silyl carbamates with isocyanatoalkylalkoxysilanes include 2,3-butanediol; 1,6-hexanediol; 1,4-cyclohexanedimethanol; 1,4-cyclohexanediol; 1,7-heptanediol; 1,8-octanediol; pentaerythritol; 1,12-dodecanediol; 1,10-decanediol; 3,6-dimethyl-4-octyne-3,6-diol; 1,9-nonanediol; bisphenol A; hydrogenated bisphenol A (i.e., 4,4xe2x80x2-isopropylidenedicyclohexanol); and 1,4-butanediol.
The reaction product of polyol and isocyanatopropyltrialkoxysilane can be a liquid of various viscosities or a solid at room temperature.
The isocyanatopropylalkoxysilane preferably has a high purity, i.e. above about 95%, and is preferably free from impurities and/or additives, such as transesterification catalysts, which can promote side reactions. Examples of undesirable transesterification catalysts are acids, bases and organometallic compounds. For isocyanatopropyltrimethoxysilane a purity of at least 98% is preferred. This may be accomplished by distilling commercially available isocyanatopropyltrimethoxysilane, available as SILQUEST(copyright) Y-5187 silane from Witco Corporation, to remove impurities such as (3-trimethoxysilylpropyl)methylcarbamate and others as well as inhibitors, catalysts and other additives.
The preferred glycols are the symmetrical ones such as 1,4-butanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol. While the reaction product of 1,4-butanediol and isocyanatopropyltriethoxysilane is a solid at room temperature, the reaction product of either 1,2-butanediol or 1,3-butanediol with isocyanatopropyltriethoxysilane is a liquid at room temperature. Similarly, the reaction product of 1,4-cyclohexanediol and isocyanatopropyltriethoxysilane is a solid at room temperature but the reaction product of 1,2-cyclohexanediol and isocyanatopropyltriethoxysilane is a liquid at room temperature.
An illustrative reaction to produce silane carbamate compounds from a diol is depicted below:
where R3 and X are as previously defined. The reaction is catalyzed by a tin catalyst such as dibutyltin dilaurate (DBTDL); dibutyltin oxide; dibutyltin dichloride; dibutyltin diacetate; dibutyltin dimaleate; dibutyltin dioctoate; dibutyltin bis(2-ethylhexanoate); tin acetate; tin octoate; tin ethylhexanoate; tin laurate. Other urethane catalysts include: K-KAT(copyright)s (zirconium, aluminum, or bismuth compounds); diazabicyclo[2,2,2]octane (DABCO); N,N-dimethylcyclohexylamine (DMCA); 1,8-diazabicyclo[5,4,0]-undec-7-ene (DBU); 1,5-diazabicyclo[2,3,0]non-5-ene (DBN). The reactions are typically exothermic and the temperature should be controlled to minimize the color in the final product. Excessive exotherm may also introduce impurities by way of side reaction. It is recommended that the exotherm be controlled so as not to allow the temperature of the reaction mixture to exceed 150xc2x0 C., more preferably no more than about 110xc2x0 C.
In a similar way triols, tetrols, pentols and hexols may be reacted with equivalent amounts of isocyanatoalkyltriethoxysilane. Such materials include gylcerine, trimethylolpropane, trimethylolethane, pentaerythritol, inositol, mannitol, sorbitol, fructose, fucose and glucose.
A preferred silane of the invention is the adduct compound prepared from two moles of isocyanatopropyltriethoxysilane and one mole of 1,4-cyclohexanedimethanol.
Examples of these carbamates include bis[3-(triethoxysilyl)propyl]-1,4-cyclohexanedimethyldicarbamate, bis[3-(trimethoxysilyl)propyl]-1,4-cyclohexanedimethyldicarbamate; bis[3-(methyldimethoxysilyl)propyl]-1,4-cyclohexanedimethyldicarbamate; bis[3-triethoxysilyl)propyl]-1,2-cyclohexanedimethyldicarbamate; bis[3-methyldiethoxysilyl)propyl]-1,2-cyclohexanedimethyldicarbamate; bis[3-triethoxysilyl)propyl]-1,4-butanedicarbamate, bis[3-(methyldiethoxysilyl)propyl]-1,4-butanedicarbamate; bis[3-triethoxysilyl)propyl]-2,3-butanedicarbamate; bis[3-(triethoxysilyl)propyl]-1,10-decanedicarbamate; bis[3-(trimethoxysilyl)propyl]-1,10-decanedicarbamate, bis[3-trimethoxysilyl)propyl]-1,6-hexanedicarbamate, tris[3-trimethoxysilyl)propyl]-1,2,3-propanetricarbamate, tris[3-triethoxysilyl)propyl]-1,2,3-propanetricarbamate, tris[3-(methyldimethoxysilyl)propyl]-1,2,3-propanetricarbamate.
Other silyl carbamates of formula II, where A=O and B=NH, may be prepared by reaction of an alkoxysilylalcohol with a polyisocyanate. Such silyl carbamates may also be made by reaction of a polyisocyanate with a terminally unsaturated alcohol, and subsequent hydrosilation.
An illustrative reaction to produce a silyl carbamate from a diisocyanate and an alkoxysilylalcohol is depicted below:
where R3 and X are as previonsly defined. This reaction may be catalyzed by the aforementioned catalysts and the same recommendations apply. Preferred compounds X(Nxe2x95x90Cxe2x95x90O)n are polyisocyanate prepolymers derived from diisocyanates and polyols. In a similar way triisocyanates, such as IPDI isocyanurate and HDI isocyanurate, may be reacted with equivalent amounts of alkoxsilyl alcohol. An alkoxysilyl polyol may be reacted with an equivalent amount of polyisocyanate in this reaction.
Examples of suitable alkoxysilyl alcohols include N(3-methyldiethoxysilylpropyl)-2-hydroxy-1-propyl carbamate;. N(3-methyldiethoxysilylpropyl)-1-hydroxy-1-propyl carbamate; N(3-triethoxysilylpropyl)-2-hydroxy-1-propyl carbamate; N(3-triethoxysilylpropyl)-1-hydroxy-1-propyl carbamate; N-(3-triethoxysilylpropyl)-4-hydroxybutyramide. Other examples are described in U.S. Pat. No. 5,587,502, the teachings of which are incorporated herein by reference. Suitable polyisocanates include, but are not limited to: 1,6-hexane diisocyanate (HDI); isophorone diisocyanate (IPDI); 2,4-toluene diisocyanate; 2,6-toluene diisocyanate; mixtures of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI); diphenylmethane 4,4-diisocyanate (MDI); bis(4-isocyanatocyclohexyl)methane (H12MDI); 1,3-(xcex1,xcex1,xcex1xe2x80x2,xcex1xe2x80x2-tetramethyl)xylene diisocyanate (TXMDI); xcex1,xcex1-dimethylmetaisopropylbenzyl isocyanate (m-TMI); and the dimers, trimers, biurets, allophanates, and other oligomers of such polyisocyanates. The polyisocyanate may also be a polymeric polyurethane xe2x80x9cprepolymerxe2x80x9d, such as those derived from the reaction of the forementioned polyisocyanates and a polyether polyol, a polyester polyol, a polybutadiene polyol or a polyacrylate polyol.
Alternatively carbamates useful in the present invention may be prepared by reaction of a terminally unsaturated alcohol with a polyisocyanate, and hydrosilation of the terminally unsaturated polyurethane intermediate in the presence of a suitable catalyst. An example of this reaction sequence, using allyl alcohol and a platinum catalyst, is depicted below:
where R1 and R2 are as previously defied, X is an organic residue group and n is 1 to 10. For example the isocyanate OCNxe2x80x94Xxe2x80x94(NCO)n can be HDI, IPDI, H12MDI, TDI, MDI, TMXDI, TMI, or a dimer, trimer, allophanate or oligomeric prepolymer thereof. A terminally unsaturated polymeric alcohol can also be used in above sequence in place of allyl alcohol. Similarly, a terminally unsaturated isocyanate can be reacted with a polyol to give a terminally unsaturated carbamate, which can be hydrosilated in lie manner:
Silane urea compounds may also be employed in the formulations of the invention. Such compounds correspond to formula II where both A and B are NH. They are suitably prepared by reaction of an alkoxysilylalkylamine with an organic isocyanate or by reaction of an organic amine with an alkoxysilylalkylisocyanate. The reaction is analogous to the reaction of isocyanate and alcohol but typically does not require a catalyst.
Examples of alkoxysilylalkylamines include 3-aminopropyltriethoxysilane (SILQUEST(copyright) A-1100); 3-aminopropyltrimethoxysilane (SILQUEST(copyright) A-1110); 3-phenylaminopropyltrimethoxysilane (SILQUEST(copyright) Y-9669); N,N-bis(3-propyltrimethoxysilyl)amine (SILQUEST(copyright) A-1170); 3-aminopropyl(methyldiethoxysilane); 3-aminopropyl(methyldimethoxysilane); aminoneohexyltriethoxysilane (SILQUEST(copyright) Y-11637).
Examples of organic (poly)amines include: n-octylamine, n-hexylamine, ethylenediamine; propylenediamine; 1,4-diaminobutane; 1,6-diaminohexane; IPDA; TDA; MDA; H12MDA. The organic amine may be polymeric, such as the JEFFAMINES(copyright) (polyether polyamines).
In all of the foregoing descriptions of synthetic methods it will be understood that if trialkoxysilane starting compounds are replaced by corresponding dialkoxyalkylsilanes, triacyloxysilanes or diacyloxyalkylsilanes, other compounds of formula I will be produced.
Other conventional additives additionally may be employed.
Examples of conventional powder coating additives which may be incorporated into the coating formations of the invention include accelerating catalysts, pigments, leveling agents, flow modifiers, light stabilizers, antioxidants, and fillers, all well known in the art. These ingredients may be employed in the inventive compositions in conventional amounts. The catalysts, typically titanate or tin compounds, are conventionally added in amounts of 0.05%-1.5% by weight, preferably 0.1%-0.5% by weight. The fillers and colorants may be added in large amounts, often as much as 50% or more, and sometimes 60% or more of the total composition weight. Clearcoat formulations may be entirely free of fillers and pigments.
The silane compounds as described above are useful as crosslinkers, as adhesion promoters, and/or as modifiers of such film properties as environmental resistance or mar resistance. At the elevated temperatures used to cure the powder coating, the carbamate groups of the molecules, if present, can react with isocyanate groups to form allophanates and biurets and/or the SiOR1 groups can react with polyols in the coating in exchange reactions.
Silanes of formula I may be employed alone or in combination with conventional crosslinking agents. They may be used to furnish the principal crosslinking network, or they may reinforce conventional crosslinking networks. In compounds where the group X is polymeric and the compound is a meltable solid, the silane of formula I may be employed as the base resin of the coating system.
In addition to the methods described above, polymeric silanes of the present invention can be synthesized by copolymerizing a silane monomer with a non-silane monomer. For example 3-methacryloxypropyltrimethoxysilane, SILQUEST(copyright)A-174, can be added to an alkyl(meth)acrylate monomer such as methyl methacrylate (and/or substituted (meth)acrylates; such as hydroxyethyl acrylate, hydroxyethyl methacrylate, glycidyl acrylate or glycidyl methacrylate) and copolymerized to give a siloxy functional poly(meth)acrylate (or if glycidyl methacrylate was included, a siloxy functionalized GMA resin).
Preferred silane compounds used in the formulations of the invention are meltable solids which make them especially suited for incorporation into conventional powder coating formulations without substantially altering the melt properties of the material. Melting points desirably will fall within the range of from about 30xc2x0 C. to about 170xc2x0 C., preferably from about 40xc2x0 C. to about 120xc2x0 C. and more preferably from about 50xc2x0 C. to about 110xc2x0 C.
The molecular weight of the silane compounds of the invention is preferably about 8000 Daltons or less, more preferably about 5000 Daltons or less.
Although solids are a preferred embodiment of the present invention, silanes in the form of liquids or waxes can be used as additives in conventional powder coating resin systems.
A preferred mode of adding silanes that are not solids is via an inert carrier, such as silica, carbon black or porous polymers. Liquids may also be added in the form of solid solutions, as a xe2x80x9cmaster-batch,xe2x80x9d or encapsulated. Silanes of the present invention may be added to a powder coating formulation via incorporation in/on pigments or fillers. Titanium dioxide is a preferred carrier for these silanes. Silanes in these forms may be added to the powder coating formulation in the same manner as solid silanes.
In a typical powder coating formulation, a useful quantity of the silane additive will be in the range of from about 0.5 to about 30% by weight of the formulation, more preferably from about 2% to about 10% by weight. In some formulations, however, higher or lower amounts may prove beneficial. Further, as noted above, silane compounds of formula I in which X is polymeric may be used as the base resin. Therefore the inventive powder coating formulations should not be considered to be restricted to these quantity ranges.
Powder adhesives may be similarly formulated. Such adhesives may be applied to one or both of the substrates to be joined in the same manner as a powder coating, for instance by electrostatic spraying, triboelectric spraying, electromagnetic brushing or via fluidized bed. The substrates are joined with heating to fuse the coating, and, if curable, allowed to cure. Upon cooling a bonded assembly is formed. Typically the size distribution of such powder adhesives is such that at least 50% by weight will pass through a 200 mesh screen.

Abstract: where R1 is a hydrocarbon, acyl, alkylsilyl or alkoxysilyl group; R2 is a monovalent hydrocarbon group; R3 is alkylene, optionally interrupted with one or more ether oxygen atoms; a is 0 or 1; Z is a direct bond or a divalent organic linking group; X is an m-valent organic group or H; and m is 1-20. The silanes are useful as crosslinkers, property modifiers and/or adhesion promoters. Powder adhesives may be similarly formed with silanes of formula I.