Switch with a fixed set of contacts and a movable set of contacts. The fixed set of contacts comprises at least one pair of fixed contacts arranged a distance apart and each having an auxiliary contact part and a main contact part. The movable set of contacts comprises at least one auxiliary contact element and a main contact element, which, when the switch is closed, are in contact, under mechanical pre-stress, with the surface of the auxiliary contact part and of the main contact part of the pair of fixed contacts and bridge the distance between the free end edges thereof facing one another, the various features being such that when the switch is closed the auxiliary contact element and the main contact element make contact more or less simultaneously with the auxiliary and with the main contact parts of the pair of fixed contacts.

The invention relates to a switch with a fixed set of contacts and a movable set of contacts, the fixed set of contacts comprising at least one pair of fixed contacts arranged a distance apart and each having an auxiliary contact part and a main contact part and the movable set of contacts comprising at least one auxiliary contact element and a main contact element, which, when the switch is closed, are in contact, under mechanical pre-stress, with the surface of the auxiliary contact part and of the main contact part, respectively, of the pair of fixed contacts and bridge the distance between the free end edges thereof facing one another, the various features being such that when the switch is closed the auxiliary contact element and the main contact element make contact more or less simultaneously with the auxiliary and with the main contact parts, respectively, of the pair of fixed contacts.
A switch of this type is disclosed in European Patent 0 281 622.
The auxiliary contact element, also referred to as the arcing contact, and the main contact element can be sliding contacts which when the switch is closed slide over the fixed contacts into their final position, that is to say the position in which the switch is fully closed. Contact rollers are generally used for closing on large short-circuit currents, for example greater than 30 kA, but contact blades can also be used. However, it is the case that the use of rollers provides a facility for using lighter weight mechanics. In principle, it is necessary only to construct the auxiliary contact elements as rolling contacts. European Patent 0 281 622 describes a switch that is suitable in particular as a current breaker. This current breaker is provided with contact rollers, all contact rollers in a set of contact rollers having the same diameter, but each pair having a different length. The two shortest rollers are positioned closest to the fixed contacts, whilst the longest rollers are furthest removed from the fixed contacts. The fixed contacts are of stepped construction at those edges thereof which face the set of contact rollers, the height of each step corresponding to the difference in length of the contact rollers. The distances between opposite steps are greater than the corresponding longitudinal dimensions of the rolling contacts, so that there is an air gap at every point between the movable contact rollers and fixed contacts when the switch is in the open position.
In the open position the movable rolling contacts are thus separated from the fixed contacts. In order to bring the switch into the closed position, the contact rollers are moved towards the fixed contacts, after which the contact rollers make contact more or less simultaneously with the pair of fixed contacts and then roll, under spring pre-stressing, over the surface of the pair of fixed contacts. In the closed position, the contact rollers are thus in contact, under mechanical pre-stress, with the surface of the pair of fixed contacts and bridge the distance between those free end edges of these fixed contacts which face one another.
The life of the known current breaker is increased by using pairs of contact rollers which as far as possible simultaneously break the contact with the fixed contacts on opening.
From FR-A-2638017 a switch with a fixed set of contacts and a movable set of contacts is known. The fixed set of contacts comprises at least one pair of fixed contacts arranged a distance apart and each having an auxiliary contact part and a main contact part. The movable set of contacts comprises at least one auxiliary contact element and a main contact element, which, when the switch is closed, are in contact under mechanical pre-stress, with the surface of the auxiliary contact part and of the main contact part of the pair of fixed contacts and bridge the distance between the free and edges thereof facing one another.
This known switch is closed and opened in three phases. For this purpose a first pair of movable knifes and a second pair of movable knifes are provided, on which a first set of main contacts and a second set of main contact together with auxiliary contacts are attached. During the closing operation first the movable and fixed auxiliary contacts contact each other, after which the first set of movable main contacts contacts the corresponding fixed contacts and finally the second set of movable main contacts may contact with the corresponding fixed main contacts. A short distance between the second movable main contacts and the second fixed main contact is provided when the first set of movable main contacts begin to engage corresponding fixed main contacts. In FR-A-2638017 a short distance between an auxiliary contact and one of the sets of main contacts are not disclosed nor clearly specified. However, from the figures of FR-A-2638017 one could derive that when the switch is closed, the main contact element makes mechanical and electrical contact with the main contact part of the fixed contacts only after the auxiliary contact element has travelled a distance over the surface of the auxiliary contact part of the fixed contacts.
The aim of this invention is to provide a switch of the type mentioned in the preamble with which the life of the switch is lengthened without additional contacts.
Said aim is achieved according to the invention in that said travelled distance is at least 2 mm
In FR-A-2638017 absolutely no indication is given that a minimum leading distance of the auxiliary contact is of essential importance when the swith is closed and absolutely not a specified minimum distance of 2 mm. The measure known per se of leading is primary used for preventing contact burning when the switch is switched out. By recognizing and using the minimal distance of the 2 mm it is possible to prolong the life of the switch without adding extra contacts. In the switch of FR-A-2638017 two set of main contacts are needed. Herein after on page 8, lines 1 and 2 it is indicated that the switch according to the present invention is suitable for closing on very high short circuit currents. Under these conditions it is just important that the condition of abovementioned minimal distance is met because just under these circumstances longer vibration time should be taken into account.
By the above-mentioned distance of 2 mm a distinct separation is obtained between the time when the movable auxiliary contact element comes into contact with the fixed contacts and the time when the main contact element comes into contact with the fixed contacts. All switching operations are now, as it were, carried out by the auxiliary contact element and virtually not by the main contact element and all closing and opening phenomena which occur during switching occur only at the auxiliary contact element and the associated auxiliary contact part of the fixed contacts. The consequence of this is that the auxiliary contact element is damaged, whilst the main contact element remains undamaged. Since the main contact element carries the major proportion of the current it is important that this main contact element remains undamaged, even when closing on a short-circuit current. An undamaged main contact element then also contributes significantly to a longer life of the switch. The phenomenon of switching with the arcing contacts only and not with the main contacts has already been known for some time from power switch technology. However, in the latter case it is not xe2x80x9cslidingxe2x80x9d contacts but xe2x80x9cbuttxe2x80x9d contacts that are concerned, as a result of which a completely different embodiment has been produced with the associated different problems. In the case of the present contact construction the contacts are pressed onto one another on short circuiting by the electromagnetic forces that arise. In the case of a contact construction with butt contacts these forces have the effect of reducing the contact pressure.
The switch according to the invention is particularly suitable as a load switch, which in general is connected in series to a safety fuse for breaking and limiting the short-circuit current and in particular is connected in series to a current-breaking and/or current limiting device. The main contact element according to the invention switches only when the short-circuit current has been clipped or limited.
In a first embodiment the movable main and auxiliary contacts are integrated in one contact.
In a second embodiment of the invention the main contact parts of the fixed contacts are located in a first plane and the auxiliary contact parts of the fixed contacts are located in a second plane that is some distance away from and parallel to the first plane and the plane of movement of the main contact element is parallel to the first plane a small distance away and the plane of movement of the auxiliary contact element is parallel to the second plane a small distance away.
In a third embodiment of the invention the main contact parts and auxiliary contact parts of the fixed contacts are located in one plane and the planes of movement of the main contact elements and the auxiliary contact elements are coincident, whilst these planes correspond to the plane of the main and auxiliary contact parts of the fixed contacts, the lengths of the auxiliary and main contact elements differing from one another in the bridging direction and the spacing of the fixed contacts in the switching direction being reduced stepwise.
It is possible to use more auxiliary contact elements one after the other in the plane of movement with more steps in the fixed contacts, the auxiliary contact elements making contact more or less simultaneously with the associated auxiliary contact parts of the fixed contacts when the switch is closed, in order to distribute the current over the auxiliary contact elements at the start of contact.
In European Patent 0 281 622 it is stated that a reduction in the repellent forces during the closing operation (repellent forces are electromagnetic forces which arise when a high current passes between two contacts brought into contact with one another) is achieved by the use of the parallel rollers. The repellent forces referred to here are forces which arise perpendicularly to the surface of the fixed contact. Another force which arises is the repulsion force. In principle, the repulsion force has the same physical background but is oriented parallel to the surface of the fixed contact. In this invention use is made of the fact that the repellent forces reduce when there are more parallel contacts, but then only if the contacts are fully engaged, for example when short-circuit currents pass through. Repulsion forces, however, arise only when a switch is closed and directly oppose the mechanics and do so significantly in the case of short circuits, as a result of which the mechanics have to be of heavier construction than is necessary.
In a further development of the second embodiment of the invention the repulsion force when the switch is closed is reduced in that a slot is made between the auxiliary contact part and the main contact part of the fixed contacts.
By making the slot in the fixed contacts the course of the current path therein is influenced in such a way that the length of the part of the current path that runs parallel to the direction of movement of the movable auxiliary contact elements in the auxiliary contact part of the fixed contacts is reduced. This reduced length results in a lower repulsion force, which is important in particular when closing on a short circuit and any reduction that can be achieved in the repulsion force translates directly back into lighter weight mechanics, which is desirable for many reasons.
It is pointed out that in German Patent Application DE 32 23 654 A1 laid open for inspection a recess is made in a fixed contact, but this recess does not run through the entire thickness of the fixed contact and thus does not have the effect of the slot according to the invention.
Furthermore, it is also pointed out that a slot in the fixed contact is known per se from German Patent DE 3 504 605 C2, but the function of this slot is to lengthen the arc when opening the switch and this cannot reduce the repulsion force of the moving contacts.
Embodiments of the slot that are preferably to be used are described in the dependent claims.
In one embodiment of the invention the auxiliary contact part of the fixed contact is narrowed to an L-shape, the free end of the leg extending in the opposing direction to the direction of movement for closing the movable auxiliary contact element and forming the track for the element. Preferably, a projection is formed on the free end of the leg, which projection extends from the track in a direction away from the free space between the fixed contacts, the free end of the movable auxiliary contact element not coming into contact with the projection when the switch is closed.
The advantage of this projection is that the foot of the arc that is produced when the switch is opened will move rapidly towards both the point of the movable auxiliary contact element and the point of the projection, as a result of which any damage will manifest itself there. These two damaged parts will, however, not come into contact with one another or with other contact parts when the switch is closed, which means that the closing and opening characteristics as well as the current-carrying characteristics are also not changed as a result of any damage as a consequence of the arc, as a result of which the life of the switch is prolonged. If this projection were not present, the arc would damage the rising edges of the contact, which has an adverse effect on the closing characteristics. This adverse effect is observed in particular when closing on short circuits and the durability of the switch will also deteriorate substantially at this point.
Embodiments of the projection which are preferably to be used and the associated part of the auxiliary contact element are described in the further dependent claims.


This invention relates to a novel process of manufacture of nanoparticles of substantially water insoluble materials from emulsions. The emulsions have the ability to form a single liquid phase upon dilution of the external phase, instantly producing dispersible solid nanoparticles. The formed nanoparticles have average diameter of about 10 to 200 nm and are suitable for drug delivery and targeting of water insoluble therapeutic or diagnostic agents. Examples of such agents are methotrexate, progesterone, testosterone, prednisolone, and ibuprofen. Such agents can be used in a wide range of therapeutic and diagnostic treatments including treatment for cancer, hormonal therapy, and pain management.

This invention relates to nanoparticles of substantially water insoluble materials, methods of preparation, and use thereof. In particular, the invention relates to nanoparticles of therapeutic and diagnostic agents, method of preparation thereof, and pharmaceutically useful dispersions containing these nanoparticles. This invention further relates to methods of treatment using these nanoparticles.
Nanoparticles of substantially water insoluble materials (i.e. materials that have water solubility of less than 0.1%) have a wide variety of applications, including therapeutic and diagnostic agents, paints, inks, dyes, and semiconductors. In most cases, performance of these nanoparticles dramatically improves as the nanoparticle size is reduced to 200 nanometers or less. Nanoparticles of therapeutic and diagnostic agents, in particular of a pharmaceutical compound (xe2x80x9cdrugxe2x80x9d) are customarily delivered with a solid or liquid carrier. Liquid containing nanoparticles such as emulsions, microemulsions and liposomes, however, usually suffer from the inherent physical instability of fluids resulting from globule dissociation. Solid polymeric or lipid nanoparticles have more structural stability, yet the rate of biodegradation of the nanoparticles and/or controlled release of the agent in the nanoparticles may not take place as intended, thereby adversely affecting optimal agent delivery and targeting. In addition, only a relatively small amount of the agent or drug can be encapsulated in fluid or solid carriers, requiring large, and sometimes impractical size dosages.
Carrier-free nanoparticles, made entirely of a water insoluble therapeutic agent or drug, have been introduced as an alternative solution for the above limitations and drawbacks. There are two major techniques described in the prior art, to produce solid drug nanoparticles. These techniques are known as wet grinding, and antisolvent precipitation. Other general techniques for nanoparticle formation, such as solvent evaporation and emulsion polymerization, are either not suitable or have not proved to be successful in making carrier-free drug nanoparticles.
Wet grinding involves the mechanical crushing of brittle crystalline drug particles, using hard beads made of glass, porcelain, zirconium oxide, or similar materials (of about 1-2 mm diameter), and aqueous solution of a hydrophilic material. The hydrophilic solution, which can be a surface active agent, surface modifier, or surface stabilizer, prevents aggregation or caking of the ground particles. An aggregate or a cake of drug particles is usually elastic in nature due to entrapped air or liquid within the void spaces between the particles and is not susceptible to further size reduction by bead bombardment. Accordingly, the wet grinding technique is not suitable for making nanoparticles from elastic materials. In addition, because the hard grinding beads can erode during grinding, remnants of the grinding beads can become incorporated in the nanoparticles, causing particle contamination.
The liquid antisolvent technique involves dissolving the water insoluble compound in suitable organic solvent, and diluting that solution with a non-solvent, which is miscible in the solution. The non-solvent neither dissolves the compound nor causes its precipitation from the original solvent. Solid nanoparticles are then generated by carefully controlling the precipitation step by addition of an antisolvent liquid (usually water or an aqueous solution). Since the formation of the nanoparticles is solely dependent on the diffusion of totally miscible liquids under non-structural geometry, or boundaries, resultant particle size, surface, and shape are critically sensitive to minimal changes in the precipitation conditions. The drawbacks of this process are that it is difficult to control and requires considerable preparation. Recently, the use of a supercritical fluid antisolvent, such as pressurized carbon dioxide, gained considerable attention because of the simpler clean up and recovery of the nanoparticles. However, supercritical fluid precipitation requires high pressure, which greatly increases the difficulty in controlling the process.
It would be desirable to have an alternative method for the preparation of substantially water insoluble nanoparticles without the drawbacks of the prior art methods.
According to one aspect, this invention provides a method of making nanoparticles of substantially insoluble water compounds and more specifically, nanoparticles of a water insoluble pharmaceutical compound (or xe2x80x9cdrugxe2x80x9d) from an emulsion in which a solution of said material forms the globules of the dispersed phase. These emulsions are readily transformed into a single uniform liquid phase, in which nanoparticles of the diagnostic or therapeutic agent are suspended, upon further dilution with the external or continuous phase. The resulting dispersed solid nanoparticles are generally less than 200 nm average diameter.
An advantageous feature of this invention is that therapeutic or diagnostic nanoparticles so produced can be utilized for intravascular injections to treat or diagnose local or systemic diseases. Another advantageous feature is that extravascular injections containing these particles can provide controlled release of the drug at the site of injection for prolonged drug effects, and minimize multiple dosing. Yet another advantage of this invention is improved drug transport across absorption barriers such as mucosal gastrointestinal barriers, nasal, pulmonary, ophthalmic, and vaginal membranes, and other distribution barriers, such as the bloodxe2x80x94tissue and bloodxe2x80x94tumor barriers of various organs and tissues. For example, anti-cancer nanoparticles of less than 50 nm diameter can migrate through the compromised, more permeable vascular bed to reach tumor tissues. Once the nanoparticles are inside the tumor tissue they will provide local cytotoxic action against the tumor cells. In the case of highly protected organs such as the brain, with its tight vascular bed surrounding the normal tissues, drug nanoparticles will preferentially concentrate in the tumor tissue, with minimal or no toxicity to the healthy brain tissue. A further advantage of this invention is the improved oral bioavailability of poorly absorbed drugs.
The formation of oil-in-water or water-in-oil emulsions is a well-known process. Emulsions suitable for generating nanoparticles of therapeutic or diagnostic agent in accordance with this invention comprise a dispersed or internal phase in which the agent is totally soluble, an appropriate emulsifier, e.g., a surfactant, and a continuous or external phase with limited solubilizing affinity to the dispersed phase.
While not intending to be confined by a particular theory, the nanoparticles described above appear to be formed by the following mechanism. After emulsification, the system comprises generally spherically shaped globules of agent surrounded by a protective sheath of emulsifier molecules. Those globules are dispersed throughout a bulk of the external phase. The emulsion will be intact as long as the protective sheath is intact and the external phase cannot dissolve the molecules of agent in the dispersed phase. Further dilution of the emulsion with the external phase will cause the sheath to become thinner, allowing the external phase to dissolve some or all of the internal phase globules. The dissolution of the internal phase globules in the external phase results in the production of nanometer-sized particles of the therapeutic or diagnostic agent. Aside from the novel procedure by which these nanoparticles are formed, a fundamental and unique feature of this invention is that precipitation of solid drug nanoparticles from the emulsion globules provides ultimate control over nanoparticle size because the resulting nanoparticles are less than or at least similar to the globule size of the initial emulsion.
Unlike the wet grinding technique, this invention can be practiced with a wide variety of therapeutic and diagnostic agents in either the crystalline or the amorphous state. Therapeutic and diagnostic agents with the following utilities can be employed in this invention:
Examples of agents that are useful include substances capable of treating or preventing an infection systemically or locally, as for example, antibacterial agents such as penicillin, cephalosporins, bacitracin, tetracycline, doxycycline, quinolines, clindamycin, and metronidazole; antiparasitic agents such as quinacrine, chloroquine and vidarabine; antifungal agents such as nystatin; antiviral agents such as acyclovir, ribarivin and interferons; anti-inflammatory agents such as hydrocortisone and prednisone; analgesic agents such as salicylic acid, acetaminophen, ibuprofen, naproxen, piroxicam, flurbiprofen and morphine; local anesthetics such as lidocaine, bupivacaine, benzocaine, and the like; immunogens (vaccines) for stimulating antibodies against hepatitis, influenza, measles, rubella, tetanus, polio and rabies; peptides such as leuprolide acetate (an LH-RH agonist), nafarelin and ganirelix.
Also useful is a substance or metabolic precursor thereof, which is capable of promoting growth and survival of cells and tissues or augmenting the functioning of cells, as for example, a nerve growth promoting substance such as a ganglioside, a nerve growth factor, and the like; a hard or soft tissue growth promoting agent such as fibronectin (FN), human growth hormone (HGH), a colony stimulating factor, bone morphogenetic protein, platelet-derived growth factor (PDGF), insulin-derived growth factor (IGF-I, IGF-II), transforming growth factor-alpha (TGF-a), transforming growth factor-xcex2 (TGF-xcex2), epidermal growth factor (EGF), fibroblast growth factor (FGF) and interleukin-1 (IL-1); an osteoinductive agent or bone growth promoting substance such as bone chips and demineralized freeze-dried bone material; and antineoplastic agents such as methotrexate, 5-fluoroacil, adriamycin, vinblastine, cisplatin, tumor-specific antibodies conjugated to toxins and tumor necrosis factor.
Other useful substances include hormones such as progesterone, testosterone, and follicle stimulating hormone (FSH) (birth control, fertility-enhancement), insulin metal complexes and somatotropins; antihistamines such as diphenhydramine and chlorpheneramine; cardiovascular agents such as digitalis glycosides, papaverine and streptokinase; anti-ulcer agents such as cimetidine, famotidine and isopropamide iodide; vasodilators such as theophylline, B-adrenergic blocking agents and minoxidil; central nervous system agents such as dopamine; antipsychotic agents such as risperidone, olanzapine; narcotic antagonists such as naltrexone, maloxone and buprenorphine.
Preferred therapeutic and diagnostic agents are water insoluble anticancer drugs such as carmustine (BCNU), antiviral drugs such as azidothymidine (AZT) and other nucleosides, HIV Protease inhibitors such as saquinavir and retinovir immune-modulating agents such as cyclosporine, natural and synthetic hormones and hormone regulators such as contraceptives. Light imaging contrast materials for x-ray imaging such as iodinated materials (Iodepamide derivatives), Magnetic Resonance imaging contrast agents such as metal oxides (Iron Fe3O4 and Fe2O2) and markers for diagnostic nuclear medicine used in scintegraphy as radio-labeled Technetium sulphur or Technetium oxide. Other preferred therapeutic agents are steroidal and non-steroidal anti-inflammatory agents such as hydrocortisone, prednisolone, ketoprofen, celecoxib and ibuprofen. Further preferred therapeutic agents are centrally acting medicines such as antiseptics, antidepressants and sedatives and cardiovascular drugs such as anti-hypertensives and blood lipid lowering agents. Particularly preferred therapeutic agents are water insoluble anti-cancer drugs, hormones, analgesics, cardiovascular, antimicrobial or anti-viral agents. This technique is also suitable for immune modulators and drugs that are soluble in dilute acids or bases. Methotrexate is a preferred drug substance that is soluble in dilute alkaline solutions.
Once the principle of the invention is understood, people experienced in the field can select suitable emulsion systems for each agent. Preferred emulsion systems are triethyl citrate-water, dimethylsulphoxide-triglyceryl cabroate and ethyl citrate-water. Alkaline or acidic aqueous solutions comprising triethyl citrate are especially useful for emulsion systems for agents of pH-selective solubility. Acids in liquid form, such as hydrochloric, acetic, phosphoric, and lactic acids are preferred for acid soluble agents. Ammonium hydroxide, triethanolamine and ethylenediamine are preferred for alkali-soluble agents.
The choice of a suitable emulsifier or a combination of emulsifiers can readily be made by those in the field.
Surfactants
Surfactants which may be used for this purpose have preferably HLB value of 1 to about 20. Examples of them are as follows:
(a) Reaction products of natural or hydrogenated vegetable oils, and ethylene glycol; i.e., polyoxyethylene glycolated natural or hydrogenated vegetable oils: for example polyoxyethylene glycolated natural or hydrogenated castor oils. Surfactants commercialized under the trade names Cremophor RH-40, Cremophor RH60, Cremophor EL, Nikkol HCO-40 and Nikkol HCo-60 may be used in the composition according to the present invention. Cremophor RH40 and Cremophor El are preferred.
(b) Polyoxyethylene sorbitan fatty acid esters: e.g., mono- and tri-lauryl, palmityl, stearyl and oleyl esters; e.g. products of the trade name xe2x80x9cTween,xe2x80x9d which includes polyoxyethylene sorbitan mono-laurate (Tween), polyoxyethylene sorbitan mono-palmitate (Tween 40), polyoxyethylene sorbitan mono-oleate (Tween 80), etc. depending on the kind of fatty acid. Tween 20 and Tween 40 can be used preferably in the composition according to the present invention.
(c) Polyoxyethylene fatty acid esters: for example, polyoxyethylene stearic acid esters of the type known and commercially available under the trade name Myrj as well as polyoxyethylene fatty acid esters known and commercially available under the trade name xe2x80x9cCetiol HE.xe2x80x9d
(d) Polyoxyethylene-polyoxypropylene co-polymers: e.g. of the type known and commercially available under the trade names xe2x80x9cPluronicxe2x80x9d and xe2x80x9cEmkalyx.xe2x80x9d
(e) Polyoxyethylene-polyoxypropylene block co-polymers: e.g. of the type known and commercially available under the trade name xe2x80x9cPoloxamer.xe2x80x9d
(f) Dioctylsuccinate, dioctylsodiumsulfosuccinate, di-[2-ethylhexyl]-succinate or sodium lauryl sulfate.
(g) Phospholipids, in particular lecithins: especially, soybean lecithin.
(h) Surfactants such as non-ionic polyoxyethylene fatty acid derivatives, in particular, polyoxyethylene sorbitan fatty acid esters (spans) such as sorbitan sesquiolate are preferred for use as emulsifiers.
Emulsification is usually performed by applying mechanical force to break down the internal phase liquid into small globules, in the range of 10 to 200 nm, more preferably less than 200 nm, and even more preferably less than 50 nm in diameter, and molecules of surfactant molecules forming a barrier between the globules and the bulk of the external liquid. Such mechanical force can be applied by mechanical stirring, ultrasonic probes, or by passing the emulsion components through narrow space, as in the case of colloidal mills, or through narrow tubes, valves or orifices. The preferred emulsification technique is passing the liquid through narrow tubes.
To obtain solid nanoparticles, the emulsion should be diluted to allow total miscibility of the liquid dispersed phase inside the continuous phase. The miscibility of the liquid dispersed phase is accompanied by the formation of the nanoparticles from the resulting one liquid phase system. The dilution step can be carried out with either an additional portion of the continuous phase solution or a liquid that is miscible with both the dispersed and continuous phases. Diluting with the same continuous phase solution is preferred.
Separation of nanoparticles can be performed using dialysis, filtration, centrifugation, or other known techniques. Nanoparticles can then be formulated into a suspension dosage form according to standard procedures in the art for injection or non-injection use. Nanoparticles can also be dried and reconstituted prior to use.
The composition of this invention enables sustained, continuous delivery of drugs, medicaments and other biologically active agents to tissues adjacent to or distant from an administration site. The biologically-active agent is capable of providing a local or systemic biological, physiological or therapeutic effect. For example, the agent may act to control infection or inflammation, enhance cell growth and tissue regeneration, control tumor growth or enhance bone growth, among other functions.
The nanoparticles of the invention can be administered using a pressure applicator such as injection into tissue through a syringe, needle, pump or similar article or by techniques known for delivering medication to parts of the human body, such as orally in a suspension, hard or soft capsules, or by topical application on the skin, to the eye, or into a mucous membrane or body cavity.
The nanoparticles of therapeutic or diagnostic agent are administered in an amount effective to provide the desired level of biological, physiological, pharmacological and/or therapeutic effect. The active agent may stimulate or inhibit a biological or physiological activity. There is generally no critical upper limit on the amount of the agent being administered. The concentration of the bioactive agent should not be so high that the composition has a consistency that inhibits its delivery to the administration site by the desired method. The lower limit of the amount of agent will depend on the activity of the agent and the period of time desired for treatment. The agent is gradually released by dissolution of the nanoparticles.
For further examples of agents that may be used in the present invention, see U.S. Pat. No. 5,324,519, the entire disclosure of which is incorporated by reference herein.
The invention is further described below with reference to various specific and preferred embodiments and techniques. The following examples are presented for illustration purposes only and are not to be taken as limiting the present invention in any way.

Method of making nanoparticles of substantially water insoluble materials

Coventry House, Apt. B2 8048 Oxford Ave.


Embodiments of the invention provide IGBT circuit modules with increased efficiencies. These efficiencies can be realized in a number of ways. In some embodiments, the gate resistance and/or voltage can be minimized. In some embodiments, the IGBT circuit module can be switched using an isolated receiver such as a fiber optic receiver. In some embodiments, a single driver can drive a single IGBT. And in some embodiments, a current bypass circuit can be included. Various other embodiments of the invention are disclosed.

The Insulated Gate Bipolar Transistor (IGBT) is a minority-carrier device with high input impedance and large bipolar current-carrying capability. Many designers view IGBTs as devices with MOS input characteristics and bipolar output characteristics that are voltage-controlled bipolar devices. The IGBT is a functional integration of Power MOSFET and BJT devices in monolithic form and combines the best attributes of both to achieve optimal device characteristics.
The IGBT is suitable for many applications in power electronics, especially in Pulse Width Modulated (PWM) servo and three-phase drives requiring high dynamic range control and low noise. It also can be used in Uninterruptible Power Supplies (UPS), Switched-Mode Power Supplies (SMPS), and other power circuits requiring high switch repetition rates. IGBT improves dynamic performance and efficiency and reduces the level of audible noise. It is equally suitable in resonant-mode converter circuits. Optimized IGBTs are available for both low conduction loss and low switching loss.

This patent is subject to a terminal disclaimer.


The invention relates to a composition based on an ethylene-vinyl alcohol copolymer comprising:

This application is related to a concurrently filed application entitled, xe2x80x9cComposition Based On An Ethylene-Vinyl Alcohol Copolymer And Its Usexe2x80x9d the inventors being, Denis Bertin, and Yves Germain, based on priority French application 99/00490 filed Jan. 19, 1999, said application being incorporated by reference herein.
The present invention relates to a composition based on an ethylene-vinyl alcohol copolymer (EVOH) and to its use.
EVOH copolymers provide a barrier to many gases and in particular to oxygen. Thus, many articles of food packaging comprise a layer consisting of an EVOH film.
The present invention relates more particularly to compositions comprising (the total being 100%):
50 to 98% by weight of an EVOH copolymer
1 to 50% by weight of a polyethylene (A)
1 to 15% by weight of a polymer (B) resulting from the reaction (i) of a copolymer (B1) of ethylene and of an unsaturated monomer X grafted or copolymerized with (ii) a polyamide (B2).
In general, EVOH copolymers have various excellent properties such as oxygen impermeability, mechanical strength, etc., and find application, as they are, in many uses as films, sheets, materials for containers, textile fibres, etc. However, this copolymer gives rise to a variation in the thickness of the product in the moulding process for manufacturing a film or a sheet, with a consequent reduction in the marketability of the product, and, because of the shortcoming in stretchability and flexibility, gives rise to non-uniform drawing during deep drawing and other processes involving a stretching force, or pinholes during the use of the product, thus imposing serious limitations on its application as a raw material for packaging. The oxygen barrier of EVOH copolymers is greatly reduced when the relative humidity (RH) increases.
In order to overcome these drawbacks, it has been attempted to laminate a material made of an impermeable resin, such as a polyolefin film, on a sheet of EVOH copolymer or to improve the stretchability and flexibility of the moulding by incorporating a polyolefin into the EVOH copolymer.
Patent Application EP 820,381 describes blends of an EVOH copolymer and 5 to 60% by weight of a polar polymer chosen from ethylene-acrylic ester copolymers, ethylene-vinyl acetate copolymers and ethylene-acrylic ester-carboxylic acid anhydride or acrylic acid copolymers. These blends become very difficult to convert as soon as the amount of polar polymer exceeds 10% by weight. The dispersion of the polar copolymer is very poor, which in turn gives poor mechanical properties. If the amount of polar copolymer exceeds 40% by weight the blend is no longer an oxygen barrier.
Application EP 440,535 describes blends of 50 to 99.5% of an EVOH copolymer, 0.4 to 50% of a polyethylene having a relative density of between 0.900 and 0.940 and of the product of the reaction of a polyolefin grafted by an unsaturated carboxylic acid with a polyamide oligomer. The compositions of the present invention are an oxygen barrier and can be easily converted. Further advantages will be described in the following text.
The invention will now be described in detail.
The EVOH copolymer is also called a saponified ethylene-vinyl acetate copolymer. The saponified ethylene-vinyl acetate copolymer to be employed according to the present invention is a copolymer having an ethylene content of 20 to 60 mol %, preferably 25 to 55 mol %, the degree of saponification of its vinyl acetate component not being less than 95 mol %.
With an ethylene content of less than 20 mol %, the property of oxygen impermeability under high humidity conditions is not as high as would be desired, whereas an ethylene content exceeding 60 mol % leads to reductions in the oxygen impermeability property, in the printability and in other physical properties. When the degree of saponification or of hydrolysis is less than 95 mol %, the oxygen impermeability property and the wet strength are sacrificed. Among these saponified copolymers, those which have melt flow indices in the range of 0.5 to 100 g/10 minutes are particularly useful.
It should be understood that this saponified copolymer may contain small amounts of other comonomer ingredients, including xcex1-olefins, such as propylene, isobutene, xcex1-octene, xcex1-dodecene, xcex1-octadecene, etc., unsaturated carboxylic acids or their salts, partial alkyl esters, complete alkyl esters, nitriles, amides and anhydrides of the said acids, and unsaturated sulphonic acids or their salts.
The oxygen permeability of the EVOH copolymer films, measured according to ASTM D 3985, is expressed in cm3 of oxygen per m2 for 24 hours for a pressure difference of 1 bar and a thickness of 25 xcexcm. To simplify matters, the oxygen permeability is called O2GTR in the rest of the text.
O2GTR varies inversely proportionally to the thickness of the film.
An EVOH comprising 38 mol % of ethylene units has an O2GTR of 0.72 at 0% RH and 3.1 at 75% RH.
An EVOH comprising 29 mol % of ethylene units has an O2GTR of 0.1 at 0% RH and 1.41 at 75% RH. These grades are produced on an industrial scale and are commercially available.
One or the other of these grades is used in different thicknesses depending on the required barrier (type of product to be preserved, preservation time, etc.). The Applicant has discovered that the compositions of the invention, based on an EVOH copolymer containing 29 mol % ethylene, have, in film form, the same barrier properties as a film essentially consisting of an EVOH copolymer containing 38 mol % ethylene but can be very easily converted. This is because the EVOH copolymer, although it is a thermoplastic, is very rigid. Its flexural modulus is about 2000 MPa. The compositions of the invention have a flexural modulus of 1500 MPa as soon as the proportion of polyethylene (A) is at least 15% by weight.
The Applicant has also discovered that films consisting of the compositions of the invention are much less sensitive to moisture, that is to say that O2GTR at 75% RH is only 1.3 to 9 times the O2GTR at 0% RH and preferably 1.3 to 3.5 times, whereas this factor is 14 in the case of films made of EVOH containing 29% ethylene.
The invention is particularly suitable for EVOH copolymers having an ethylene content ranging from 25 to 45 mol % and MFIs (Melt Flow Index according to ASTM D 1238) ranging from 1.5 to 4 (g/10 minutes at 190xc2x0 C./2.16 kg) and from 5 to 30 (g/10 minutes at 230xc2x0 C./2.16 kg).
With regard to the polyethylene (A), this is chosen from ethylene homopolymers or ethylene copolymers.
By way of comonomers, mentioned may be made of:
alpha-olefins, advantageously those having from 3 to 30 carbon atoms.
Examples of alpha-olefins having 3 to 30 carbon atoms as possible comonomers comprise propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, 1-dococene, 1-tetracocene, 1-hexacocene, 1-octacocene and 1-triacontene. These alpha-olefins may be used by themselves or as a mixture of two or more of them;
the esters of unsaturated carboxylic acids such as, for example, alkyl (meth)acrylates, the alkyls possibly having up to 24 carbon atoms.
Examples of alkyl acrylates or methacrylates are, especially, methyl methacrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate and 2-ethylhexyl acrylate;
vinyl esters of saturated carboxylic acids such as, for example, vinyl acetate or vinyl propionate;
unsaturated epoxides.
Examples of unsaturated epoxides are especially:
aliphatic glycidyl esters and ethers, such as allyl glycidyl ether, vinyl glycidyl ether, glycidyl maleate, glycidyl itaconate, glycidyl acrylate and glycidyl methacrylate, and
alicyclic glycidyl esters and ethers, such as 2-cyclohexen-1-yl glycidyl ether, diglycidyl cyclohexene-4,5-dicarboxylate, glycidyl cyclohexene-4-carboxylate, glycidyl 2-methyl-5-norbornene-2-carboxylate and di-glycidyl endo-cis-bicyclo[2.2.1]hept-5-ene-2,3-dicar-boxylate;
unsaturated carboxylic acids, their salts and their anhydrides.
Examples of anhydrides of an unsaturated dicarboxylic acid are, especially, maleic anhydride, itaconic anhydride, citraconic anhydride and tetrahydrophthalic anhydride;
dienes such as, for example, 1,4-hexadiene.
(A) may comprise several comonomers.
Advantageously, polymer (A), which may be a blend of several polymers, comprises at least 50% and preferably 75% (in moles) of ethylene. The density of (A) may be between 0.86 and 0.98 g/cm3. The MFI (viscosity index at 190xc2x0 C./2.16 kg) is advantageously between 1 and 1000 g/10 min.
By way of example of polymers (A), mention may be made of:
low-density polyethylene (LDPE);
high-density polyethylene (HDPE);
linear low-density polyethylene (LLDPE);
very low-density polyethylene (VLDPE);
polyethylene obtained by metallocene catalysis, that is to say polymers obtained by the copolymerization of ethylene and of an alpha-olefin such as propylene, butene, hexene or octene in the presence of a single-site catalyst generally consisting of a zirconium or titanium atom and of two alkyl cyclic molecules linked to the metal. More specifically, the metallocene catalysts are usually composed of two cyclopentadiene rings linked to the metal. These catalysts are frequently used with aluminoxanes as cocatalysts or activators, preferably methyl aluminoxane (MAO). Hafnium may also be used as the metal to which the cyclopentadiene is fixed. Other metallocenes may include transition metals of Groups IVA, VA and VIA. Metals from the series of lanthanides may also be used;
EPR (ethylene-propylene rubber) elastomers;
EPDM (ethylene-propylene-diene monomer) elastomers;
ethylene-alkyl (meth)acrylate copolymers possibly containing up to 60%, and preferably 2 to 40%, by weight of (meth)acrylate;
ethylene-alkyl (meth)acrylate-maleic anhydride copolymers obtained by copolymerization of the three monomers, the proportions of (meth)acrylate being as in the above copolymers, the amount of maleic anhydride being up to 10% and preferably 0.2 to 6% by weight;
ethylene-vinyl acetate-maleic anhydride copolymers obtained by copolymerization of the three monomers, the proportions being the same as in the previous copolymer.
Advantageously, (A) is chosen from copolymers of ethylene and alkyl (meth)acrylates. The alkyl may have up to 24 carbon atoms. Preferably, the (meth)acrylates are chosen from those mentioned above. Copolymers (A) advantageously comprise up to 40% by weight of (meth)acrylate and preferably 3 to 35%. Their MFI is advantageously between 0.1 and 50 (at 190xc2x0 C./2.16 kg).
With regard to polymer (B), the starting point is the preparation of (B1) which is either a copolymer of ethylene and an unsaturated monomer X, or a polyethylene onto which an unsaturated monomer X is grafted. X is any unsaturated monomer that can be copolymerized with ethylene or grafted onto polyethylene and having a functional group that can react with a polyamide. This functional group may be a carboxylic acid, a dicarboxylic acid anhydride, an epoxide, etc.
By way of examples of monomer X, mention may be made of (meth)acrylic acid, maleic anhydride etc., unsaturated epoxides such as glycidyl (meth)acrylate. Advantageously, maleic anhydride is used. With regard to grafted polyethylenes, it is possible to graft X onto the polyethylenes that were described under (A). The grafting is an operation known per se. With regard to the copolymers of ethylene and the monomer X, that is to say those in which X is not grafted, it is advantageous to use ethylene-maleic anhydride and ethylene-alkyl (meth)acrylate-maleic anhydride copolymers. These copolymers comprise from 0.2 to 10% by weight of maleic anhydride and from 0 to 40% by weight of alkyl (meth)acrylate. Their MFI is between 1 and 50 (190xc2x0 C./2.16 kg). The alkyl (meth)acrylates have already been described above in the case of polymer (A).
Polyamide (B2) should be understood to mean the products of the condensation:
of one or more amino acids, such as aminocaproic, 7-aminoheptanoic, 11-aminoundecanoic and 12-aminododecanoic acids or of one or more lactams, such as caprolactam, oenantholactam and lauryllactam;
of one or more salts or mixtures of diamines, such as hexamethylenediamine, dodecamethylenediamine, metaxylylenediamine, bis(p-aminocyclohexyl)methane and trimethylhexamethylenediamine with diacids, such as isophthalic, terephthalic, adipic, azeleic, suberic, sebacic and dodecanedicarboxylic acids;
or of mixtures of several monomers, thereby resulting in copolyamides.
Blends of polyamides may be used. Advantageously, PA-11, PA-12, the copolyamide containing nylon-6 units and nylon-12 units (PA-6/12) and the copolyamide based on caprolactam, hexamethylenediamine and adipic acid (PA-6/6,6) may be used.
(B2) is a polyamide or a polyamide oligomer. Polyamide oligomers are described in EP 342,066.
The polyamides B2 may have acid, amine or monoamine terminal groups. For the polyamide to have a monoamine terminal group, all that is required is to use a chain stopper of formula:
in which:
R1 is hydrogen or a linear or branched alkyl group containing up to 20 carbon atoms;
R2 is a group having up to 20 linear or branched, alkyl or alkenyl carbon atoms, a saturated or unsaturated cycloaliphatic radical, an aromatic radical or a combination of the above. The stopper may, for example, be laurylamine or oleylamine.
Advantageously, B2 is a PA-6, a PA-11 or a PA-12.
The proportion of B2 in B1+B2 by weight is advantageously between 0.1 and 60%.
The reaction of (B1) with (B2) preferably takes place in the molten state. (B1) and (B2) may, for example, be blended in an extruder at a temperature generally of between 230 and 250xc2x0 C. The average residence time of the melt in the extruder may be between 10 seconds and 3 minutes, and preferably between 1 and 2 minutes.
According to a preferred embodiment of the invention, polyethylene (A) is an ethylene-alkyl (meth)acrylate copolymer and copolymer (B1) is an ethylene-alkyl (meth)acrylate-maleic anhydride copolymer. Preferably, the (meth)acrylates of (A) and (B1) are the same.
Particularly advantageous compositions comprise (the total being 100%):
55 to 98% EVOH copolymer
1 to 44% polyethylene (A)
1 to 10% polyethylene (B)
and preferably
55 to 75% EVOH copolymer
15 to 25% polyethylene (A)
5 to 15% polyethylene (B).
The compositions of the invention may be prepared by melt blending them in extruders (single-screw or twin-screw), BUSS kneaders, BRABENDER mixers and, in general, the usual devices for blending thermoplastics.
The compositions of the invention are particularly suitable for conversion by the usual techniques for thermoplastics. They may be made into film, for example by casting or by extrusion-blowing.
The compositions of the invention are useful as a barrier layer in multilayer packaging. They comprise, for example, a polyolefin layer, a binder, a layer of the compositions of the invention, a binder layer and a polyolefin layer.
They may be in the form of flexible packaging or of bottles or containers.
Such packaging is manufactured by coextrusion or by injection-blow moulding. The applicant has also discovered that the compositions of the invention exhibit a good adhesion to PET; thus in the previous packagings, bottles and containers it is not necessary to put a binder between the compositions and the PET. This property is usefull in coinjection to make preforms of bioriented bottles an flasks.

Composition based on an ethylene-vinyl alcohol copolymer and its use

Abstract: 1 to 15% by weight of a polymer (B) resulting from the reaction (i) of a copolymer (B1) of ethylene and of an unsaturated monomer X grafted or copolymerized with (ii) a polyamide (B2). It also relates to a multilayer structure comprising a layer consisting of this composition. This structure is useful for making packaging. The composition of the invention also adheres well to PET, this property being useful in coinjection to make bioriented preforms.


A holder for attaching articles to the belt of a user includes at least one aperture though which the belt is threaded. The belt goes between the front side of the holder and the back side of a pants belt loop. An article strap which is connected to an article such as a tool is then threaded in front of the top of the holder, behind the belt, and again in front of the bottom of holder. In this fashion, the pants belt loop and the article strap serve to retain the holder in place with respect to the pants belt loop.

The present invention pertains to devices for holding articles, and more particularly to a holder for tools, knives, keys, and the like, which is attached to the belt and pants belt loop of a user.
Devices for holding articles on belts are well known in the art. U.S. Pat. No. 5,582,338 shows a tool holder for carrying a cutting implement, such as a pair of lopping shears, having a plurality of blades attached by a pivot to a pair of elongated handles. The tool holder includes a support backing containing a plurality of vertically extending slots. A waist belt may be passed through the vertically extending slots so that the tool holder may be suspended from the waist belt.
U.S. Pat. No. 5,176,302 illustrates a holder for the handle of a container comprising a substantially rigid, continuous wire-like member bent to form a belt receiving portion and an integral handle receiving portion. The belt receiving portion stabilizes the position of the holder and the handle receiving portion is provided with first and second locking portions through which the container handle must pass before resting at the bottom of the handle receiving portion. The container is thus maintained in a stable, convenient position when the wearer is moving his body and/or walking, freeing the user""s hands for other operations while at the same time permitting convenient access to the contents of the can.
U.S. Pat. No. 4,986,459 discloses a tool holder which efficiently organizes a bartender""s tools. The tool holder has a pliable support, a first pocket for holding a pen, a hook attached to the first side of the support for holding a bottle opener, a second pocket attached to the first side of the support for holding a lighter, a third pocket attached to the first side of the support for holding a knife, and a ring attached to the first side of the support for holding a towel. The support may be secured to the body of a user by way of a belt so that the second side of the support is adjacent a hip of the user. A hook-and-pile fastening arrangement may be used to releasably fasten the support to the belt at a desired position.
U.S. Pat. No. 4,917,281 shows a holster for carrying a rechargeable electric drill. The holster has a contoured tapering back panel terminating at an upper end in an elongated strap including a snap fastener for securement around a wearer""s belt.
U.S. Pat. No. 4,805,819 illustrates a sheath for housing a retractable knife both in its retracted or unretracted state. The sheath has a pair of pockets, one adapted to receive the knife blade and a second adapted to receive the knife when the blade is housed within its handle. The sheath is additionally capable of being folded into a more compact form when housing a retracted knife.
U.S. Pat. No. 4,790,461 shows a holder for a claw hammer having an elongated handle and a claw and head member carried by and projecting generally from one end of the handle. The holder has a waist belt, a support pad carried by the waist belt, and a cradle-like collar defining a tool storage opening for receiving the tool including a partial loop and a hinged gate.
U.S. Pat. No. 4,718,585 is directed to a holster for carrying a hand gun in a compartment on its outer surface. A belt loop is provided on the inner surface of the body. A first tab and a second tab are joined to opposite sides of the body. The tabs include belt loops on their respective inner surfaces. The tabs are aligned on the body so that the belt loops of the first tab, second tab and body can simultaneously receive a belt. When worn, a trouser belt loop can be inserted between the first tab loop and the body loop, or between the second tab loop and the body loop, to prevent the holster from sliding with respect to a belt.
U.S. Pat. No. 2,817,887 pertains to a limb holder for use by fruit pickers, orchardists, and other persons who need to manipulate the limbs and branches of shrubs and trees. The limb holder is removably attached to a person""s trouser belt.
The present invention is directed to a holder for holding articles such as tools. The articles are attached to the holder using an article strap. The present invention is useful in any situation where the user wants to hold an article to his or her belt. The holder is attached to the belt of the user, and cooperates with the belt, a pants belt loop, and the article strap. The interwoven spatial arrangement of the holder, belt, belt loop, and article strap combine to lock the holder to the pants belt loop, even when the user takes the pants off.
In accordance with a preferred embodiment of the invention, the holder includes a flat plate having a first end, an opposite second end, a front side, and an opposite back side. The first end has a first aperture for receiving the belt, and the second end has a second aperture for receiving the belt. The first aperture also receives the article strap. The plate also has a protruding portion which has a hole. The hole may be used to attach a second article or tool.
In accordance with another preferred embodiment of the invention, (1) the back side of the plate is placed on the front side of the pants belt loop, (2) the belt is threaded (feed) through the first aperture, then under the back side of the pants belt loop, then behind the back side of the plate, and through the second aperture, and (3) the article strap is threaded between the front side of the plate and the belt, along the back side of the belt, and between the front side of the plate and the belt again, thereby retaining the holder in place with respect to the pants belt loop.
In accordance with another preferred embodiment of the invention, the second aperture is eliminated, and the holder will still be held in place with respect to the pants belt loop.
In accordance with an important aspect of the invention, the plate is curved to better fit the contour of the user""s waist.
In accordance with an important feature of the invention, the front side of the plate has an area upon which indicia such as advertising may be disposed.
In accordance with another important aspect of the invention, the width of the first aperture is wider than the sum of the widths of the pants belt loop and the article strap. In this fashion both the pants belt loop and the article strap will fit in the first aperture.
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.

Holder for articles which attaches to a belt and a pants belt loop and method of use


Acylphosphine initiators used in making ophthalmic lenses are stabilized by the addition of an acid to the monomer mix used to make the lenses.

This invention relates to the use of photoiniators. More particularly, it relates to the stabilization of photoinitiators useful in processes for making ophthalmic lenses.
Ophthalmic lenses such as contact lenses are often made in processes that employ photoinitiated polymerization reactions. UV and visible radiation are most frequently used to initiate cure in these reactions. It is often desirable to prepare a mixture of materials together with an initiator or initiator system (where initiation involves more than one component) and other additives that will ultimately form the lens upon completion of the reactions. These types of mixtures are referred to as the xe2x80x9cmonomer mixxe2x80x9d in this context. Stability of the initiator can be a crucial factor in the working time and shelf life of the monomer mix. Increasing the working time of the monomer mix is desirable since it reduces the need for preparation of starting materials and the possibility of introducing lot to lot and intra-lot variations in lens production. Acylphosphines are an interesting and useful class of initiators for free radical polymerations of the type frequently used to made ophthalmic lenses. Reaction mechanisms for many of these materials are described in Reaction Mechanism of Monoacyl- and Bisacyiphoine Oxide Photoinitiators Studied by 31P, 13C-, and 1H-CIDNP and ESR, Ursul Kolczak, Gunther Rise, Kurt Dietliker, and Jacob Wirz, 118 J. Am. Chem. Soc., 6477 (1996). Bisacylphosphines and their use are further described in U.S. Pat. No. 5,534,559 and JP-A-8-259642 incorporated herein by reference.
Unfortunately, this class of compounds tends to be unstable in a variety of environments lessening its potential as an active initiator. EP 849,296 proposes a method of stabilizing bisacylphosphine initiators used in the production of urethane (meth)acrylate polymers used for coatings. The method involves combining the monomer components together with the initiator in the presence of a tertiary amine and in the absence of a tin component. Japanese patents JP-A-4-6125; JP-A-296315; JP-A8-127630 propose similar methods of stabilizing monoacylphospine photoinitiators in the presence of a tin compound used as a polymerization catalyst.
Unfortunately, these solutions are not desirable when applied to monomer mixes used to make ophthalmic lenses because of the potentially deleterious effect they may have on various components of the monomer mix. This is particularly true where the monomer mix is used to make silicone hydrogel lenses.
A new method for stabilizing acylphosphine initiators is desirable.
The invention is a stable monomer mix for making ophthalmic lenses. The stable monomer mix is made by admixing a monomer mixture, an initiator, and an acid.
In another aspect of the invention a silicone hydrogel monomer formulation is made by admixing a silicone hydrogel forming mixture, an initiator, and an acid.
In yet another aspect of the invention, a method of stabilizing an initiator system comprises lowering the pH of the initiator system.
In yet another aspect of the invention, a process for stabilizing a silicone hydrogel monomer formulation in an admixture of a reactive silicone macromer and a photoiniator comprises admixing an acid with the admixture of macromer and photoinitiator.
The initiators of this invention are those having the following structure:
wherein, R1, R2, and R3 are each independently H or a C1-12 substituted or unsubstituted alkyl cycloalkyl, or aromatic moiety provided that at least one of R1, R2 and R3 has the following structure:
and is attached to the P at the acyl carbon, and wherein, R4-R8 are independently, H or a C1-3 substituted or unsubstituted alkyl or alkoxy moiety.
In each case, where an R1-R8 group is substituted, the substituent can comprise a hydroxy or C1-4 alkyl alkoxy, alkenyl, or alkynyl group. Substitution with hetero atoms such as nitrogen, sulfur, and halo atoms is possible but is not favored.
It is preferred that R1 and R2 are both Structure II moieties with R4 and R8 substituents. It is most preferred that R4 and R8 are methoxy groups. It is further preferred in this embodiment that R3 is a C1-10 alkyl alkoxy, or alkenyl group substituted with C1-2 alkyl groups; most preferably a substituted pentyl group.
In the most preferred embodiment, R1 and R2 are both Structure II moieties with R4 and R8 being methoxy groups; R1 is a trimethyl pentyl group. Thus, the most preferred embodiment has the following structure:
Theses initiators can be used alone or in combination with other initiators such as benzoin methyl ether, 1-hydroxycyclohexyl phenyl ketone, Irgacure 1850 brand photoinitiator, 1-hydroxy cyclohexyl phenyl ketone (commercially available as xe2x80x9cIrgacure 184xe2x80x9d); 2-benzyl-2-n-dimethylamino-1-(4-morpholinophenyl)-i-butanone (commercially available as xe2x80x9cIrgacure 369xe2x80x9d); 1-hydroxycyclohexyl phenyl ketone (50% by weight) plus benzophenone(commercially available as xe2x80x9cIrgacure 500xe2x80x9d); 4-(2-hydroxyethoxy) phenyl-(2-hydroxy propyl)ketone (commercially available as xe2x80x9cIrgacure 2959xe2x80x9d); 2,4,6-Trimethyl benzoyl diphenyl phosphineoxide (TPO) (50% by weight) plus 2-hydroxy-2-methyl-1-phenyl-propan-1-one (HMPP) (50% by weight) (commercially available as xe2x80x9cDarocur 4265xe2x80x9d); 2,2-dimethoxy-2-phenylacetophenone (BDK) (commercially available as xe2x80x9cIrgacure 651xe2x80x9d); bis (n1-2,4-cyclopentadien-1-yl), bis (2,6-difluoro-3-(IH-pyrrol-1-yl)phenyl) Titanium (CGI-784); 2-methyl-1-(4-(methylthio)phenyl)-2-morpholino propan-1-one (MAP) (commercially available as xe2x80x9cIrgacure 907xe2x80x9d); 2-hydroxy-2-methyl-1-phenyl-propan-1-one (HMPP) (commercially available as xe2x80x9cDarocur 1173xe2x80x9d); or mixtures thereof. Mixtures that include a UV and visible light initiator system are preferred as they permit more flexible use of UV blockers in the monomer mix.
The stabilizers useful in this invention are acids. These are preferably weak organic acids but may include strong inorganic acids as well as Lewis acids. Additionally, precursors capable of generating acids in the reaction mixture can also be used. The most preferred acids are acetic acid, formic acid, propionic acid, and acrylic acid.
The inorganic acids include, for example, hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, hydroiodic acid, hydrofluoric acid, sulfurous acid, nitric acid, nitrous acid, phosphorous acid, perchloric acid, chloric acid, chlorous acid, iodic acid, bromic acid, arsenic acid, carbonic acid, selenium hydride, tellurium hydride, phosphonic acid, hypophosphoric acid, diphosphonic acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acid, selenic acid, selenious acid, telluric acid, tellurous acid, arsenious acid, antimonic acid, antimonous acid, borofluoric acid, etc.
The organic acids include, for example, the sulfonic acids such as hydroxymethanesulfonic acid, trifluoromethanesulfonic acid, beta-bromoethanesulfonic acid, allylsulfonic acid, 2-methyl-2-[(1-oxo-2-propenyl)amino]-1-propanesulfonic acid, D-10-camphorsulfonic acid, benzenesulfonic acid, m-nitrobenzenesulfonic acid, m-benzenedisulfonic acid, methanesulfonic acid, ethanesulfonic acid, 2-hydroxyethanesulfonic acid, 2-(cyclohexenylamino)methanesulfonic acid, (3-cyclohexenylamino)methanesulfonic acid, p-ethylbenzenesulfonic acid, alpha-naphthalenesulfonic acid, beta-naphthalenesulfonic acid, p-toluenesulfonic acid, p-chloromethylbenzenesulfonic acid, p-phenolsulfonic acid, 2-pyridylhydroxymethanesulfonic acid, 2,6-naphthalenedisulfonic acid, etc.; the organic sulfinic acids such as benzenesulfinic acid, p-toluenesuifinic acid, etc.; the organic phosphoric acids such as phenylphosphonous acid, butyphosphonous acid, methylphosphonous acid, dibenzenephosphinic acid, dibutylphosphinic acid, benzenephosphonic acid, methylphosphonic acid, phenylphosphinic acid, methylphosphinic acid, dibenzenethiophosphinic acid, dibutylthiophosphinic acid, benzenethiophosphonic acid, methylthiophosphonic acid, phenylthiophosphinic acid, methylthiophosphinic acid, benzenethiophosphonous acid, dibutylthiophosphonous acid, diethyl dithiophosphate, alpha-hydroxybenzylphosphonous acid, toluenephosphonous acid, etc.; the substituted or non-substituted aliphatic carboxylic acids include for example mandelic acid, acetic acid, lactic acid, ascorbic acid, phenylacetic acid, bromoacetic acid, trichloroacetic acid, chlorodifluoroacetic acid, thioacetic acid, glycolacetic acid, glyoxylic acid, acrylic acid, beta chloroacrylic acid, cyanoacetic acid, ethoxyacetic acid, beta-chloropropionic acid, perfluoropropionic acid, propiolic acid, n-butyric acid, isobutyric acid, alpha-hydroxyisobutyric acid, crotonic acid, mucochloric acid, cyclopropanecarboxylic acid, isovaleric acid, 1-methylcyclopropanecarboxylic acid, 1-cyanocyclopropanecarboxylic acid, cyclobutanecarboxylic acid, cyclopentanecarboxylic acid, 2-ketobutyric acid, levulinic acid, pivalic acid, tert-butylacetic acid, coumarinic acid, 3-cyclohexenecarboxylic acid, beta-2-furylacrylic acid, 3-pyridylacetic acid, phenylthioacetic acid, m-chlorophenylacetic acid, o-nitrophenylacetic acid, p-fluorophenylacetic acid, o-hydroxyphenylacetic acid, phenoxyacetic acid, o-chlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, 2,4,5-richlorophenoxyacetic acid, cyclohexylacetic acid, 1-methyl-1-cyclohexanecarboxylic acid, 6-acetamidohexanoic acid, heptylic acid, dl-terebic acid, benzoylformic acid, cinnamic acid, o-chlorocinnamic acid, 2,4-dichlorociniumic acid, m-nitrocinnamic acid, o-hydroxycinnamic acid, d-2-phenoxypropionic acid, 3-phenoxypropionic acid, 3-phenylpropionic acid, 3-(p-hydroxyphenyl)propionic acid, 2-(2,4,5-trichlorophenoxy)propionic acid, 4-methoxyphenylacetic acid, p-chloro-2-methylphenylacetic acid, 3,4-methylenedioxyphenylacetic acid, 4-chloro-2-methylphenoxyacetic acid, m-tolylacetic acid, alpha, alpha, alpha-trifluoro-m-tolylacetic acid, p-hydroxyphenylpyruvic acid, alpha-cyanocinnamic acid, p-methoxycinnamic acid, m-trifluoromethylcinnamic acid, 3,4-methylenedioxycinnamic acid 3,4 dimethoxyphenylacetic acid, (xe2x88x92)-alpha-methoxy-alpha-trifluoromethylphenylacetic acid, 1,4-benzdioxane-6-acetic acid, 3-phenyl-n-butyric acid, 1-phenyl-1-cyclopropanecarboxylic acid, 2-(p-methoxyphenyl)-acetylene-1-carboxylic acid, 3-benzoylpropionic acid, 2-(p-chlorophenoxy)-2-methylpropionic acid, alpha-naphthylacctic acid, beta-naphthoxyacetic acid, 3,4,5-trimethoxyphenylacetic acid, diphenylacetic acid, bis(p-chlorophenyl)acetic acid, 1-menthoxyacetic acid, diphenyleneacetic acid, 1-phenylcyclopentanecarboxylic acid, 1-(p-chlorophenyl)-1-cyclopentanecarboxylic acid, dl-3-camphorcarboxylic acid, palmitic acid, stearic acid, benzilic acid, desoxycholic acid, linolic acid, oleic acid, alpha-acetamidocinnamic acid, etc.; the aromatic carboxylic acids include for example benzoic acid, salicylic acid, o-toluic acid, alpha, alpha, alpha-trifluoro-m-toluic acid, p-ethylbenzoic acid, 2,6-dimethylbenzoic acid, 2,4,6-trimethylbenzoic acid, p-tertbutylbenzoic acid, p-bromomethylbenzoic acid, 2-biphenylcarboxylic acid, 4,4xe2x80x2-methylenebis(3-hydroxy-beta-naphthoic acid), alpha-naphthoic acid, p-benzoylbenzoic acid, phthalamic acid, o-phthalaldehydic acid, m-nitrobenzoic acid, 3,4-dinitrobenzoic acid, m-cyanobenzoic acid, thiosalicylic acid, gallic acid, m-hydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 1-hydroxy-2-naphthoic acid, o-anisic acid, 3,4-dimethoxybenzoic acid, 4-hydroxy-3-methoxybenzoic acid, 4-hydroxy-3,5-dimethoxybenzoic acid, 4-n-butoxybenzoic acid, 3-phenoxybenzoic acid, piperonylic acid, o-acetamidobenzoic acid, p-chlorobenzoic acid, 3,5-dichlorobenzoic acid, o-fluorobenzoic acid, m-fluorobenzoic acid, 2,6-difluorobenzoic acid, 2,6-dichlorobenzoic acid, 2,3,5-triiodobenzoic acid, 4-chlorosalicylic acid, 3-nitrosalicylic acid, 5-bromosalicylic acid, 2-chloro-3-nitrobenzoic acid, 3-chloro-4-hydroxybenzoic acid, 3,5-dichloro-4-hydroxybenzoic acid, 3-chloro-4-methylbenzoic acid, 3-methoxy-4-nitrobenzoic acid, 3-methoxy-4-hydroxybenzoic acid, 3-methoxy-4-methylbenzoic acid, 3-methyl-2-nitrobenzoic acid, 3-hydroxy-4-nitrobenzoic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, o-thymotinic acid, etc.; the heteroaromatic carboxylic acids include for example N-methylpyrrole-2-carboxylic acid, 2-furancarboxylic acid, 5-bromo-2-furancarboxylic acid, pyrrole-2-carboxylic acid, 3-furancarboxylic acid, nicotinic acid, isonicotinic acid, citrainic acid, alpha-picolinic acid, etc.; the substituted or non-substituted aliphatic polyhydric carboxylic acids include for example succinic acid, fumaric acid, maleic acid, malic acid, tartaric acid, citric acid, oxalic acid, malonic acid, ethylmalonic acid, hydroxymalonic acid, methylsuccinic acid, 2-methyl-2-phenylsuccmnic acid, 2-ethyl-2-methylsuccinic acid, 2-isopropylsuccinic acid, bromosuccinic acid, 2,3-dibromosuccinic acid, alpha-ketoglutaric acid, 3-ethyl-3-methylglutaric acid, glutaconic acid, itaconic acid, mesaconic acid, citraconic acid, adipic acid, camphoric acid, diglycollic acid, acetylenedicarboxylic acid, dimethylcyclopropanedicarboxylic acid, etc.; the aromatic dicarboxylic acids include for example phthalic acid, isophthalic acid, terephthalic acid, homophthalic acid, 3-nitrophthalic acid, 4-hydroxyisophthalic acid, tetrachlorophthalic acid tetrachloroterephthalic acid, nitroterephthalic acid, pyrazine-2,3-dicarboxylic acid, o-phenylenediacetic acid, 5,5xe2x80x2-methylenedisalicylic acid, etc.; the phenols include for example picric acid, 2,4-dinitrophenol, 2,6-dinitrophenol, 2,6-diiodo-4-nitrophenol, 2,6-dichloro-4-nitrophenol, 2,5-dichloro-4-nitrophenol, 2,6-dibromo-4-nitrophenol, 2-bromo-4-chloro-6-nitrophenol, 2-dichloro-6-nitrophenol, etc.; and the substituted or non-substituted dithiocarbamic acids include for example 2-cyclohexenyldithiocarbamic acid, 2-cycloheptenyldithiocarbamic acid, methyldithiocarbamic acid, dimethyldithiocarbamic acid, ethylenebis(dithiocarbamic acid), etc.
Lewis acids include, for example, boron trifluoride, boron trichloride, boron tribromide, aluminum fluoride, aluminum chloride, aluminum bromide, aluminum iodide, aluminum sulfate, iron fluoride, iron chloride, iron bromide, iron nitrate, iron sulfate, gallium fluoride, gallium chloride, antimony fluoride, antimony chloride, antimony sulfte, indium fluoride, indium chloride, tin fluoride, tin chloride, tin bromide, tin iodide, arsenic fluoride, arsenic chloride, zinc fluoride, zinc chloride, zinc bromide, zinc iodide, copper chloride, barium chloride, silver chloride, etc.
It is generally desirable that acids used in the practice of this invention are of such molarity or concentration that they imbue the monomer mix in which they are to be used with a pH of 3 to 8. Preferably, it is less than 7. While the upper end of the pH scale to which the monomer mix could be lowered is slightly alkaline, the addition of acid lowers the pH to point that it would not otherwise reside. In any event, in the case of a monoprotic acid such as HCL, about 0.1 to about 10 weight % of acid is used in the monomer mix. Based on this, the skilled artisan can readily determine equivalent ranges for other acids useful in the practice of this invention.
Making the lenses of this invention is conducted by combining the components of the monomer mix together with the initiators and stabilizers described above according to well known methods of lens formation such as photoinitiated casting in lens molds.
Silicone hydrogels have high oxygen permeability making them particularly desirable for use in the lenses of this invention. When the monomer mix comprises components for the preparation of silicone hydrogels, it is referred to herein as a silicone hydrogel forming mixture. Silicone hydrogels are preferably prepared by polymerizing a mixture containing at least one silicone-containing monomer and at least one hydrophilic monomer. Either the silicone-containing monomer or the hydrophilic monomer may function as a crosslinking agent or a separate crosslinker may be employed. Crosslinking agents are monomers having multiple polymerizable moieties. The term xe2x80x9cmonomerxe2x80x9d when used in this sense refers to a material used in forming the ultimate polymer system The crosslinking agent can be monomeric, dimeric, trimeric, or polymeric molecules and still be considered a monomer with respect to the silicone hydrogel ultimately produced from it. The polymerizable functionalities generally bond to more than one polymer chain creating a network or network-like polymeric structure. There are numerous silicone-containing monomeric units commonly used in the formation of silicone hydrogels. U.S. Pat. Nos. 4,136,250; 4,153,641; 4,740,533; 5,034,461; 5,070,215; 5,260,000; 5,310,779; and 5,358,995 provide some useful examples and each is incorporated herein by reference.
Hydrophilic monomers that have previously been found useful for making silicone hydrogels include: unsaturated carboxylic acids, such as methacrylic and acrylic acids; acrylic substituted alcohols, such as 2-hydroxyethylmethacrylate and 2-hydroxyethylacrylate; vinyl lactams, such as N-vinyl pyrrolidone; and acrylamides, such as methacrylamide and N,N-dimethylacrylamide. Still further examples are the hydrophilic vinyl carbonate or vinyl carbamate monomers disclosed in U.S. Pat. No. 5,070,215, and the hydrophilic oxazolone monomers disclosed in U.S. Pat. No. 4,910,277 and each is incorporated herein by reference.
The preferred components of the monomer mix used to make the silicone hydrogel lenses of this invention include, for example, siloxanes and acrylic/methacrylic acid and derivatives, polyvinyl, typically di- or tri-vinyl monomers, such as di- or tri(meth)acrylates of diethyleneglycol, triethyleneglycol, butyleneglycol and hexane-1,6-diol; divinylbenzene. In the preferred embodiment, the siloxane component is a polydimethyl siloxane. It is combined with a hydrophilic monomer such as hydroxyethyl methacrylate or acrylate derivative. In the most preferred embodiment, the monomers comprise mono-alkyl terminated polydimethylsiloxanes (xe2x80x9cmPDMSxe2x80x9d) such as monomethacryloxy propyl terminated polydimethyl siloxane and a macromer comprising the reaction product of 2-hydroxyethyl methacrylate, methyl methacrylate, methacryloxypropykris(trimethylsiloxy)silane, mono-methacryloxypropyl terminated mono-butyl terminated polydimethylsiloxane, and 3-isopropenyl-xcex1,xcex1-dimethylbenzyl isocyanate. Additionally preferred monomers include, for example, methacryloxypropyl tris(trimethyl siloxy) silane, xe2x80x9cTRISxe2x80x9d; N,N-dimethyl acrylamide, xe2x80x9cDMAxe2x80x9d; triethyleneglycoldimethacrylate, xe2x80x9cTEGDMAxe2x80x9d. Other monomers and crosslinking agents known in the art for making silicone hydrogels can also be used.
The employment of mPDMS is noteworthy as it is thought to be responsible for imbuing the resulting hydrogel with improved mechanical properties such as reduced elastic modulus and tan xcex4 (loss modulus of the material divided by its elastic modulus or Gxe2x80x3/Gxe2x80x2) without compromising monomer compatibility during the polymerization process. Unlike many of the siloxanes predominantly used at present, mPDMS has no polar functionality and is of relatively high molecular weight. Measures to improve its incorporation are thus welcome. The structure of mPDMS can be described as follows:
where b=0 to 100, and R57 is any C1-10 aliphatic or aromatic group which may include hetero atoms; provided that R57 is not functionalized at the point at which it is bonded to Si. C3-8 alkyl groups are preferred with butyl groups, particularly sec-butyl groups, being most preferred. R56 is any single polymerizable vinyl group. Preferably it is a methacryl moiety but it can also be an acryl or styrenic moiety or other similar moiety.
The monomer mix also includes the initiators and acids described above. These can be added to the mix before, during, or after the mix is combined in a lens mold or other vessel for lens formation.
It is also desirable to carry out the cure in the presence of a diluent. Suitable diluents include alkanols, N,N-dimethylformamide acetamide, acetonitrile, N,N-diethylacetanide, heptane, dimethyl sulfoxide, acetone, tert-butyl acetate, ethyl acetate, isopropyl acetate, and N-methyl-2-pyrrolidone. Low molecular weight (C5-12) akanols are preferred. Dimethyl-3octanol is most preferred.


A device for dispensing animal scents, for the attracting of animals such as deer comprising a cylindrical outer housing, an inner assembly, slidably received within the housing and an absorbent wick disposed within the inner assembly for saturation with a liquid attractant such as deer urine. The inner assembly comprises a hollow cylinder with a wick disposed there through, and has a plurality of holes allowing the scent given off from the liquid attractant to diffuse into the air. The device can be selectively closed when so desired to prevent unnecessary dissipation of the attractant, and further prevent unnecessary evaporation.

The present invention relates to aroma dispensers. Specifically this invention relates to an aroma dispensing apparatus for selectively dispensing animal attractant scents, but the apparatus may also be used for dispensing other materials, such as room deodorizers and the like.
The use of scents or lures to attract animals is well known. The use of deer scents such as doe urine to attract deer, particularly bucks, has become more popular in recent years. While baiting game animals is generally illegal, the use of scents is allowed. Many animals including deer rely on the smell of urine and glandular secretions to communicate dominance and sexual activity. When used correctly, urine is the most reliable scent communicator, and provides for an excellent aid in hunting. When you use an animal scent as a hunting tool, it must remain fresh, so as to maintain its efficiency. Such scents are dispensed in a number of ways, and oftentimes, a hunter will use it on his clothing to mask his natural odors. Other times it is distributed at a site to attract game to that location.
One of the most effective devices for dispensing game scents is the type embodying a wick, or other absorbent material. The wick is saturated with an attractant in liquid form, which subsequently diffuses the odor into the air as the scent evaporates off the wick. When not in use, the diffusion device requires a closing means, preventing the attractant from excess evaporation, and furthermore eliminating the undesirable odor often produced from such attractants.
Numerous patents have been issued for game scent dispensing systems employing a wick for carrying the attractant, varying in their means of enclosing the wick for storing and transporting. U.S. Pat. No. 5,074,439 issued to Wilcox, discloses a sealable pouch, containing an absorbent pad saturated with attractant. The pouch is subsequently attached to the hunter by a lanyard. U.S. Pat. No. 4,302,899 issued to Dehart, discloses a sponge type wick within a housing, for mounting in a variety of locations. U.S. Pat. No. 5,263,274 issued to Speed, teaches of a pair of reservoirs connected by an exposed central string-like wick. Attractant flows from the upper reservoir down the wick to the lower reservoir. U.S. Pat. No. 6,241,161 issued to Corbett discloses a container and a flexible cylindrical core containing a wick, which can be hung in a specific location from a lanyard, or partially pushed into the ground with the assistance of a conical ended container. The main disadvantage being the method of securing the wick within the container when not in use may be prone to opening, thereby releasing the attractant; when it is undesired to do so.
In light of the aforementioned patents and inventions, it thus is seen that a need remains for a device for easily dispensing animal scents which is convenient to use, easy to transport, and can be securely sealed when so desired. Accordingly it is to the provision of such a device that the present invention is primarily directed.
It is therefore an object of the present invention to provide for a device for dispensing a wide variety of different scents, preferably, but not necessarily animal scents, wherein the attractant is contained within an inner sealable wick.
It is a more specific object of the present invention to provide for a refillable device for dispensing animal scents which is refillable once the attractant has significantly diffused, or if it is desired, to replace or exchange the attractant material for any reason, i.e. attractant has become rancid.
It is another object of the present invention to provide for a sealable device for dispensing animal scents that can be easily transported without concern that it may possibly open when undesired.
It is a further object of the present invention to provide for a device for dispensing animal scents which comprises a single component once assembled, preventing the separation and loss of separate parts.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.


A safety device in a gas lighter to prevent release of gas fuel stored in the lighter when a safety button is in a locked position to thereby prevent ignition of the lighter, and to allow release of gas fuel when the safety button is moved from the locked position to an unlocked position. An indentation in the safety button coacts with an end portion of a housing of the lighter to releasably retain the safety button in the unlocked position when moved there by a user's finger. Projections provided on the underside of a gas-release button guide the safety button's movement between the locked and unlocked positions and releasably retain the safety button in the unlocked position. The safety button is moved from the unlocked to the locked position when the gas-release button is released after ignition of the lighter.

1. Field of the Invention
The present invention relates to a gas lighter having a safety device which prevents inadvertent ignition of the lighter. In particular, when in a locked position the safety device prevents the release of gas fuel so that the lighter cannot be ignited.
2. DESCRIPTION OF RELATED ART
Commercially available gas lighters are dangerous if handled carelessly, particularly by young children. The inadvertent ignition of such gas lighters has resulted in fires causing property damage and injury to people. Furthermore, in most of the gas lighters that are available, the gas-release button is normally located on the outside of the case. In these lighters gas fuel can be accidentally released while the lighter is being carried. Therefore, there is a need for a safety device, which in a locked position prevents the inadvertent release of gas fuel and also makes the lighters difficult for children to operate. Gas lighters sold in commerce are now required by federal law to have ignition safety devices to prevent young children from being able to ignite the lighters.
U.S. Pat. No. 5,002,482, to Fairbanks et al., discloses a safety device with a safety latch that prevents movement of an actuator means for releasing fuel stored in the lighter. When fuel is to be released to ignite the lighter, the safety latch is moved cross-wise and upwards towards a guide notch in the actuator means, thereby allowing movement of the actuator means to release the fuel.
This lighter, however, is complicated to manufacture because a portion of the housing and the actuator means must be cut out to form the guide notch for movement of the safety latch. Moreover, the lighter is overly difficult to use because of the multiple directions and forces required to release the safety latch.

Gas lighter with safety device to prevent release of gas

c/o Bultina America Corp., 2334 E. Valencia Dr.