SILICONE RUBBER-CONTAINING, AFTERGLOWING PREPARATION, PRODUCT PROVIDED THEREWITH AND USE THEREOF

Abstract: A silicone rubber-containing, afterglowing preparation, which is characterized in that said silicone rubber is a curable silicone rubber and that the composition includes 0.1 - 10 per cent by weight of an afterglowing pigment. In a preferred embodiment, the silicone rubber is capable of being cured at a temperature of 5 - 170 DEG C, in particular by means of moisture or a peroxide compound, whereby the silicone rubber is transparent after curing.

Description: SILICONE RUBBER-CONTAINING, AFTERGLOWING PREPARATION, PRODUCT PROVIDED THEREWITH AND USE THEREOF The invention relates to a silicone rubber-containing, afterglowing preparation. The invention furthermore relates to a product provided with a silicone rubber-containing, afterglowing preparation and to the use of such a preparation. From US Patent No. 5,506,474 an adhesive with a base of silicone rubber is known, which contains calcium carbonate as a filler and titanium dioxide as a light-reflecting agent. Said adhesive may furthermore contain marble dust, denatured alcohol and triethanol amine. According to a preferred embodiment said adhesive furthermore includes an agent which reflects UV radiation having a wavelength of less than 300 nm, such as antimonium trioxide. According to said US patent specification said adhesive is very suitable for connecting a tubular lamp to a lamp base being suitable for that purpose. An adhesive of this kind is not suitable for certain uses, however, because the adhesive will only reflect light upon being exposed to light. Furthermore said adhesive will reflect the light at practically the same wavelength, or practically the same wavelength range, as that of the light to which it is being exposed. This means that if the adhesive would be irradiated with visible "white" light (wavelength range approximately 400 - 800 nm), only "white" light will be reflected. It will be apparent, therefore, that such an adhesive is not suitable for use as a signalling means which is capable of delivering a light signal in case of certain emergencies. Such an emergency may for example be an indoor fire accompanied by strong smoke production, whereby the electric power is cut off by the fire or has to be cut off for safety reasons. It will be apparent that so-called emergency lighting is not suitable for this land of situations, either. The object of the present invention is to provide a solution for the above- described problems. The invention therefore relates to a silicone rubber- containing, afterglowing preparation, which is characterized in that said silicone rubber is a curable silicone rubber and that the composition includes 0.1 - 10 per cent by weight of an afterglowing pigment. The term afterglowing pigment used herein is understood to mean an fluorescent and/or a phosphorescent pigment. Fluorescence is the process wherein radiation is emitted as a result of a transition between two molecular energy levels comprising the same spinning condition (mostly singlet-singlet transition), whilst in the case of phosphorescence radiation is emitted as a result of a transition between two molecular energy levels comprising different spinning conditions (mostly triplet-singlet transition). Fluorescence is very brief and can generally be detected only when a fluorescent pigment is exposed to light. Phosphorescent pigments, however, are capable of emitting light for a much longer period of time after being exposed to light. Another advantage of both fluorescent and phosphorescent pigments is that they can emit light of a different wavelength or wavelength range than the light with which they are being irradiated or with which they were originally irradiated. Thus a pigment of this kind is capable of emitting light of a certain colour or shade upon or after being irradiated with for example "white" light. The preparation according to the invention preferably includes 0.5 - 8% by weight, in particular 1 - 4% by weight, of the afterglowing pigment when said pigment is an allcaline earth metal- containing aluminate which is doped with one or more transition metals. The preparation according to the invention preferably includes 0.1 - 30% by weight, and in particular 0.5 - 25% by weight, of the afterglowing pigment when said pigment is a pigment according to prior art, for example a pigment which consists of zinc sulphide and copper only. The silicone rubber in the silicone rubber-containing, afterglowing preparation is preferably a silicone rubber which has a viscosity in the range of 100 - 1 ,000,000 cSt. at 25 °C. Furthermore the silicone rubber is preferably a polydialkyl siloxane, which is capable of being cured at a temperature of about 5 - 130°C, preferably at a temperature of 20 - 120°C, and in particular at a temperature of 25 - 100°C. Said polysiloxane is in particular a polydimethyl siloxane. When the silicone rubber is capable of being cured at about room temperature (this is about 25 °C), curing may take place by means of water or a water- containing agent such as moisture (single-component silicone rubber), for example, or by means of an acetoxysilane, an alkoxysilane (two-component silicone rubber). When the silicone rubber is a two-component silicone rubber, curing may for example take place in the presence of a catalyst, such as dibutyl tin laureate, for example. When the silicone rubber is capable of being cured at temperatures of up to about 170 °C, curing of the silicone rubber may take place by means of a peroxide-free vulcanisation system or by a peroxide compound, such as dibenzoyl peroxide, bis(2.4-dichlorobenzoyl) peroxide, t- butyperoxy-benzoate or dicumyl peroxide, for example. According to the invention the silicone rubber is preferably cured by means of moisture or by means of a peroxide compound of a peroxide-free compound. Advantageously the silicone rubber according to the invention is transparent after curing. The advantage of this is that less afterglowing pigment needs to be included in the silicone rubber-containing, afterglowing preparation in order to provide sufficient afterglow. The preparation according to the invention may include one or more usual colorants and/or other (fluorescent and/or phosphorescent) pigments and or plasticizers. As described above, the afterglowing pigment may be a fluorescent and/or a phosphorescent pigment. According to the invention the afterglowing pigment is in any case a phosphorescent pigment, so that the pigment, after being exposed to light, is capable of emitting light in turn, which light may have a different wavelength or a different wavelength range than the light to which it was initially exposed. It will be apparent to those skilled in the art that the preparation according to the invention may also include more than one fluorescent and/or phosphorescent pigment. The afterglowing pigment according to the invention preferably contains an allcaline earth metal-containing aluminate, which is doped with one or more transition metals, and/or a mixture including zinc sulphide and copper. The afterglowing pigment is in particular an alkaline earth metal-containing aluminate which is doped with one or more transition metals and which has a density of about 3.5 g/ml. The afterglowing pigment has an average particle size distribution of 1 - 100 μm, preferably 5 - 50 μm, and in particular 10 - 25 μm. The afterglowing pigment may be irradiated with light having a wavelength range of about 350 - 450 nm, preferably about 380 - 400 nm. The afterglowing pigment preferably emits light having a maximum wavelength of about 520 nm and a wavelength range of 475 - 575 nm. The afterglow and the afterglow intensity in accordance with DIN 67510, part 4 ( 1995) of the afterglowing pigment is at least 1350 minutes, preferably at least 2000 minutes, at a visibility limit of 0.3 mcd/m 2 . The intensity of the light emitted by the afterglowing pigment is at least 170 mcd/m 2 , preferably at least 400 mcd/m 2 , after 5 minutes, at least 25 mcd/m 2 , preferably at least 65 mcd/m 2 , after 30 minutes, and at least 5 mcd/m 2 , preferably at least 1 1 mcd/m 2 , after 120 minutes. The afterglowing preparation according to the invention preferably emits white to yellowish light. The invention furthermore relates to a product provided with a silicone rubber-containing, afterglowing preparation. The preparation according to the invention may be provided in the same manner, for example by means of a tube containing the preparation and a so-called putty gun, as other agents used for sealing cracks, holes, fissures, seams and the like. The preparation according to the invention is excellently suited for use in for example buildings, in tunnels, on roads, in windows and the like, and it is preferably applied in places which are not trodden on or which are infrequently used. Places where the preparation according to the invention can be very suitably applied include those parts of steps which are not trodden on during normal use and door posts, for example. The preparation according to the invention may furthermore be applied in places where emergency lighting is present or must be present. The afterglowing preparation according to the invention may be used in particular as a signalling means in case of certain emergency conditions, such as fires accompanied by strong smoke production, in particular in those cases where the electric power has to be cut off or is cut off by the fire, as a result of which the emergency lighting that may be present no longer operates. At elevated temperatures, such as those that occur during a fire, the amount of light emitted by the afterglowing preparation is increased. Afterglowing preparation which has not been exposed to light first is capable of emitting light as a result of elevated temperatures that occur in case of fire, for example. The afterglowing preparation may be prepared in the usual manner by means of the usual mixing apparatus. Example A silicone rubber-containing, afterglowing preparation was prepared by mixing an amount of 4 g of an afterglowing pigment of type Lumilux Groen SN (Product No. 50061 ) marketed by the firm of Riedel-de Haen of Seelze, Germany, with 100 g of a silicone rubber of the polydimethyl siloxane type (Silglaze N from General Electric). Said mixing, preferably in a closed mixing apparatus, is continued until a homogeneous dispersion of the pigment in the silicone rubber is obtained.

Claims: CLAIMS 1. A silicone rubber-containing, afterglowing preparation, characterized in that said silicone rubber is a curable silicone rubber and that the composition includes 0.1 - 10 per cent by weight of an afterglowing pigment. 2. A silicone rubber-containing, afterglowing preparation according to claim 1 , characterized in that said silicone rubber is capable of being cured at a temperature of 5 - 170°C. 3. A silicone rubber-containing, afterglowing preparation according to claim 1 or 2, characterized in that said silicone rubber is a silicone rubber which can be cured by means of moisture or a peroxide compound. 4. A silicone rubber-containing, afterglowing preparation according to any one of the claims 1- 3, characterized in that said silicone rubber is transparent after curing. 5. A silicone rubber-containing, afterglowing preparation according to any one of the claims 1- 4, characterized in that said afterglowing pigment has an afterglow of at least 1350 minutes, preferably at least 2000 minutes, at a visibility limit of 0.3 mcd/m 2 . 6. A silicone rubber-containing, afterglowing preparation according to any one of the claims 1- 5, characterized in that the intensity of the light emitted by said afterglowing pigment is at least 170 mcd/m 2 , preferably at least 400 mcd/m 2 , after 5 minutes. 7. A silicone rubber-containing, afterglowing preparation according to any one of the claims 1- 6, characterized in that said afterglowing pigment emits white to yellowish light. 8. A silicone rubber-containing, afterglowing preparation according to any one of the claims 1- 7, characterized in that said afterglowing preparation will emit light at elevated temperatures without first having been exposed to light. 9. A product provided with a silicone rubber-containing, afterglowing preparation according to claims 1 - 8. 10. Use of a silicone rubber-containing, afterglowing preparation according to claims I - 8 as a signalling means.

Inventors: BEELE JOHANNES ALFRED, BEELE, JOHANNES, ALFRED
Applicants: BEELE ENG BV, BEELE JOHANNES ALFRED, BEELE ENGINEERING B.V., BEELE, JOHANNES, ALFRED
Application year: 1997
Main classification: C09K11
IPC codes: C09K11