Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/267—Marking of plastic artifacts, e.g. with laser
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/262—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used recording or marking of inorganic surfaces or materials, e.g. glass, metal, or ceramics

Definitions

• This invention relates to a composition upon which an image can be produced by subjecting the surface thereof to a source of intense radiation, and to the process for producing an image thereon.
• the substrate is coated with a layer of a composition containing a material that absorbs the' radiant energy and becomes vaporized or is otherwise removed from the surface of the substrate.
• radiant energy absorbing materials include various dyes and pigments, such as carbon black, and various metals, such as aluminum. If a metallic layer is coated over a dark substrate, for example, selective removal of the metallic layer will produce a positive image. If, however, a dark pigmented layer is coated over a transparent or light substrate, selective removal of the dark layer will result in a negative image.
• Electronic components such as dual inline packages (DIPs)
• DIPs dual inline packages
• the coated components are then selectively subjected to laser radiation which removes the coating from the areas exposed to produce an image, such as a part number or other form of identification.
• the electronic components are cleaned, for example in an HCI bath. Coatings containing metallic particles are attacked by the bath to a sufficient degree to cause severe contamination of the bath and destruction of the coating.
• One of the major drawbacks of the laser-imagable coating compositions that have been used is the difficulty associated with matching the color of the coating to the color of the potting compound for the electronic component. Different manufacturers prefer to distinguish their products using different colors. If the laser-imagable coating were metallic, it would have to be coated over a dark colored surface to provide the necessary contrast to the areas in which the coating had been removed by the laser. If, on the other hand, a pigment such as carbon black were to be employed in the coating, there would not be sufficient contrast against the dark background of the potting compound.
• compositions are prepared in which images are produced when the compositions are subjected to intense radiation.
• the compositions comprise either a clay or barium sulfate or a mixture thereof in a binder material which will not be destroyed and which will not mask the image produced upon exposure to intense radiation.
• the binder material can comprise any natural or synthetic resin material or any vitreous or ceramic material.
• the composition is essentially transparent or translucent and the image produced upon exposure to radiation is white in color.
• the index of refraction of the binder material is greater than that of the clay or barium sulfate.
• compositions of the present invention can be used in a variety of applications, such as coating compositions, molding compounds, potting compounds for encapsulating electronic components or in any other way used to render an article or a surface thereof imagable upon exposure to intense radiation:
• compositions which contain clay and/or barium sulfate in accordance with the present invention, it has been found that many different articles or surfaces can be rendered imagable or markable with a laser or other source of high intensity radiant energy.
• This invention significantly increases the versatility of laser marking systems, which are presently limited to the use of a few laser imagable coatings for electronic components.
• compositions are prepared in which images can be produced upon exposure to high intensity radiant energy.
• the compositions comprise either a clay or barium sulfate or a mixture of both in a binder material which is not destroyed during exposure to radiation and which does not mask the image produced upon irradiation of the composition.
• compositions can contain any of the clays and other aluminum silicate-containing materials which occur naturally. Both hydrated and anhydrous aluminum silicate clays can be used.
• the clay should be added to the compositions of the present invention in finely divided particulate form, such as in the form of thin flat plates.
• the particle size of the clay has been found not to be important insofar as its ability to function in accordance with the present invention. The smaller the particle size, the more durable to abrasion the coating will be. The coating will also be smoother and more aesthetically pleasing with a smaller particle size.
• the amount of clay present in the composition can vary widely. If barium sulfate is present in the composition, no clay need be present. If no barium sulfate is included, however, then the upper limit is simply a function of the surface area of the clay used and the viscosity and rheological properties desired for the composition. The upper limit will be less than the critical pigment volume content (CPVC) of the composition.
• CPVC critical pigment volume content
• the CPVC of a coating composition represents the densest packing of the pigment particles commensurate with the degree of dispersion of the system.
• the degree of pigment dispersion exerts a major influence on a CPVC value.
• a vehicle of high dispersive capacity such as the linseed oil called for in the oil absorption test, will produce a substantially completely dispersed pigment state yielding a maximum CPVC value.
• a vehicle of lower dispersive capacity will give a reduced CPVC value in proportion to the flocculation that remains undispersed in the coating composition. See T. Patton, Paint Flow and Pigment Dispersion, Chap. 7, pp. 184-187 (1966).
• the compositions will comprise up to about 65 percent by weight, and preferably in the range of from about 15 to about 35 percent by weight, of the clay.
• compositions of the present invention can also contain barium sulfate in lieu of or in addition to the clay.
• Any barium sulfate or barite can be employed in finely divided particulate form.
• the particle size of the barium sulfate is only important with respect to the durability and aesthetics of the composition desired.
• the amount of barium sulfate included in the composition can likewise vary over a large range. If some clay is present in the composition, then no barium sulfate need be included. In the absence of clay, the upper limit on the amount of barium sulfate is governed by the critical pigment volume concentration of the composition. In general, the compositions will comprise up to about 80 percent by weight, and preferably from about 25 to about 50 percent by weight, of barium sulfate.
• compositions of the present invention preferably contain both clay and barium sulfate. It has been observed that when only clay was added, the images produced were not as bright as when both clay and barium sulfate were included, and that when only barium sulfate was added, a higher energy level was required to produce images having the same degree of brightness and clarity as when both clay and barium sulfate were used. Thus, the combination of both materials appears to provide superior image contrast and brightness to that obtained using either material alone. As with either material alone, the upper limit on the amount of clay and barium sulfate in the composition must be below the CPVC.
• the compositions comprise from about 3 to about 35 percent by weight of clay together with from about 15 to about 60 percent by weight of barium sulfate.
• compositions further comprise a binder material for the clay and the barium sulfate.
• a binder material for the clay and the barium sulfate Since the imagable compositions of the present invention can be used in a variety of ways to prepare articles or surfaces of articles that can be imaged by exposure to intense radiation, the composition of the binder is primarily a function of the end use of the imagable composition. If the imagable composition is to be employed as a coating for electronic components, then any conventional coating composition can be used as the binder, provided it exhibits the other characteristics of the binder compositions described herein. Similarly, if the imagable composition is to be used as a potting compound or molding compound, then a conventional potting compound or molding compound can be used as the binder for the clay and barium sulfate.
• the binder material should have an index of refraction greater than the index of refraction of the clay or of the barium sulfate. If the index of refraction of the binder is less than that of the clay or of the barium sulfate, then these materials will act as pigments to render the composition opaque upon drying or curing. An image will not be produced upon exposure to intense radiation if the clay and barium sulfate act as pigments for the binder.
• the binder composition not contain any ingredient that will mask the image produced upon exposure to radiation.
• the principal ingredient used to bind the particles of clay and barium sulfate can be any of the natural or synthetic resins or polymers used to prepare coating, molding, potting or other compositions, such as acrylics, epoxies, phenolics, urea-formaldehydes, polyesters, varnishes, lacquers, shellacs, elastomers, and other resinous materials. It is also possible to employ glass, ceramic or other vitreous materials as the binder.
• the binder can be any material that will hold the particles of clay and barium sulfate together sufficiently to form a surface in which an image can be formed.
• a dye or pigment can be added to the binder composition to produce an article or coating of a desired color, provided that the binder composition in the absence of the dye or pigment has an index of refraction greater than that of the clay or barium sulfate. If the binder composition contains too large an amount of the pigment or dye, however, the image produced upon irradiation of the composition will simply be masked by the color of the pigment or - dye, provided that the dye or pigment is not itself destroyed by the radiation.
• the binder compositions can also contain any of the conventional additives and modifiers which are generally included in such compositions, such as plasticizers, lubricants, adhesion promoters, flow modifiers, initiators, fungicides, curing agents and the like, depending upon the particular end use of each.
• compositions of the present invention can be employed to provide surfaces upon which images can be produced with high intensity radiant energy. Because many different types of binders can be used to prepare the present compositions, these compositions can be tailored to many widely differing applications. For example, laser marking systems are presently used to produce images on electronic components by subjecting a component coated with. a composition containing a laser radiation absorbing material to an imagewise pattern of laser radiation. The coating is removed from the component in the areas subjected to radiation. As discussed above, however, the inability to provide coating compositions that match the colors of the potting compounds for the electronic components and provide sufficient image contrast upon irradiation has severely limited the acceptability of such laser marking systems.
• the composition is substantially transparent or translucent and changes color to white upon exposure to intense radiation.
• Such compositions are prepared by employing a binder material having an index of refraction greater than the index of refraction of either the clay or the barium sulfate.
• the clay and the barium sulfate in their finely divided form are white in color.
• a binder material such as a resin having a greater index of refraction
• an opalescent material is obtained which cures or dries to a substantially transparent or translucent material.
• the compositions should not contain any ingredient that would increase the opacity of the composition.
• substantially transparent coating compositions can be prepared, there is no longer any need to select dyes or pigments that match the color of the coating to the color of the potting compound of the electronic component and that change color or are destroyed to provide images of sufficient contrast.
• the white-colored image produced on the transparent coating will provide sufficient contrast against any darker -color of the component over which it is coated.
• the manufacturer will always maintain the desired color of the potting compound and will obtain sufficient contrast between the image and the background against which it is produced.
• the manufacturer of the electronic components could prepare a potting compound containing clay and barium sulfate in accordance with the present invention.
• a potting compound containing clay and barium sulfate in accordance with the present invention.
• the manufacturer would entirely eliminate the need for a coating on the electronic components to provide an imagable surface, since the image could then be produced directly on the surface of the potting compound.
• the article is not usually made from a composition that contains a filler material, then the article can be coated with a coating composition containing clay and barium sulfate in accordance with the present invention to render the coated surfaces of the article imagable upon exposure to intense radiation.
• articles which are made from natural or synthetic resins such as molded or extruded articles, films, coating compositions, such as paints and inks, and potting compounds can be prepared in accordance with the present invention.
• coating compositions such as paints and inks
• potting compounds can be prepared in accordance with the present invention.
• glass or ceramic articles or coatings can be rendered imagable.
• an image can be produced on a substrate by providing the substrate with a surface made of the composition of the present invention. Since the image is to be formed in the surface of the substrate, only the surface need be made of the present composition, although the entire substrate could be made of the composition.
• the surface of the substrate to be imaged is then subjected to a source of intense radiant energy.
• Suitable sources of intense radiation include lasers, gas discharge lamps, such as xenon flash lamps, and the like.
• the surface of the substrate should be exposed to a source of radiation having a sufficient energy density for a period of time sufficient to produce an image in the areas exposed to the intense radiation. An energy density of from about 0.7 to about 6.0 joules/cm. 2 has been found to be suitable.
• the substrate typically is exposed to the source of radiation in the pattern of the image to be produced in the surface. Only those areas of the. substrate on which an image is desired are subjected to the radiation. This imagewise exposure can be achieved, for example, using a mask, stencil, or other similar means for producing a pattern.
• the surface of the substrate changes color in the areas exposed to produce the desired image.
• the binder material for the clay and barium sulfate is substantially transparent and colorless, then the image produced will appear white by contrast.
• the binder is made of a material that changes color or contains a dye or pigment which wholly or partially masks the image, then the image will appear as white or as a lighter shade of the color of the binder in contrast to a dark background, due to the underlying white image.
• the clay and barium sulfate were in an acrylic binder material, a clear colorless coating would be produced.
• the contrast of the image produced is less than that desired, it can be improved by adjusting the amount of the clay and barium sulfate in the binder, the energy density of the source of intense radiation, the duration of the exposure to the radiation, and the color of the binder material or of the background against which the image is produced.
• An epoxy resin premix was prepared by mixing about 45.5 parts of an epoxy solution containing about 54.2 percent of a bisphenol A glycidyl ether epoxy resin and about 45.8 percent of tributyl phosphate, about 43.1 parts of a solution containing about 60 percent of a cross-linking resin for the epoxy and about 40 percent of tributyl phosphate, about 6 parts of a solution containing about 80 percent of a heat activated curing agent for the epoxy and about 20 percent of tributyl phosphate, about 3.2 parts of a thixotropic bodying agent, about 1.4 parts of an adhesion promoter, and about 0.7 parts of a fungicide using a high speed disk disperser set at a disk tip speed of 600 ft/min.
• a black, heat curable coating composition was then prepared by mixing 50 grams of the above premix with 75 grams of barium sulfate, 30 grams of titanium dioxide, and 15 grams of graphite. The mixture was then transferred to a three-roll mill for processing twice through the mill.
• a portion of the coating composition was then coated over the surface of the potting compound of an electronic component at a wet thickness of 0.75 to 1.0 mil using a Markem Model 20A body coating apparatus.
• the coated electronic component was then heated to cure the coating.
• the cured coating comprised about 49.9 percent of barium sulfate, about 19.9 percent of titanium dioxide, about 10 percent of graphite and about 20.2 percent of epoxy binder.
• the coated electronic component was then exposed to a pulsed TEA C0 2 laser for the duration of one laser pulse.
• the laser was operated at 30 KV with a 2:1 beam reduction and produced an energy density of 2.5 joules/cm. 2 .
• the duration of the laser pulse was 100 nanoseconds.
• a metal imaging stencil was placed in the path of the laser beam. A white image was produced in the black coating which corresponded to the pattern in the stencil.
• a black, heat curable coating composition was prepared by mixing 30 grams of the epoxy resin premix prepared in Example 1 above with 5 grams of a mineral black which contained a small amount of a carbon black mordanted onto clay following the procedure of Example 1.
• the composition was then coated onto The potting compound for an electronic component and cured.
• the cured coating comprised about 21.5 percent of the mineral black and about 78.5 percent of the epoxy resin binder.
• the coated electronic component was then exposed to an imagewise pattern of laser radiation.
• a white image was produced in the black coating in the areas exposed to the laser radiation.
• a black coating composition was prepared by mixing 30 grams of the epoxy resin premix of Example 1 with 2 grams of mineral black and 10 grams of barium sulfate.
• the composition was then coated onto an electronic component potting compound and cured.
• the cured coating comprised about 6.6 percent of the mineral black, about 33.1 percent of the barium sulfate and about 60.3 percent of the epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation.
• a white image was produced in the very transparent black coating in the areas exposed to the laser radiation.
• a black coating composition was prepared by mixing 30 grams of the epoxy resin premix of Example 1 with 5 grams of mineral black and 10 grams of barium sulfate.
• the composition was then coated onto an electronic component potting compound and cured.
• the cured coating comprised about 15.1 percent of mineral black, about 30.1 percent of barium sulfate and about 54.8 percent of the epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation. A fair to good white image was produced in the coating in the areas exposed to the laser radiation.
• a black coating composition was prepared by mixing 30 grams of the epoxy resin premix of Example 1 with 7 grams of mineral black and 20 grams of barium sulfate.
• the composition was then coated onto an electronic component potting compound and cured.
• the cured coating comprised about 15.5 percent of mineral black, about 44.2 percent of barium sulfate and about 40.3 percent of the epoxy resin binder.
• a fair white image was produced in the coating in the areas exposed to an imagewise pattern of laser radiation.
• a black coating composition was prepared by mixing 57 grams of the coating composition prepared in Example 5 with 20 grams of a urea-formaldehyde resin.
• the composition was then coated onto an electronic component potting compound and cured.
• the cured coating comprised about 10.7 percent of mineral black, about 30.7 percent of barium sulfate, and about 58.6 percent of epoxy and urea-formaldehyde resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation. A very good white image was produced in the coating in the areas exposed to the laser radiation.
• a black coating composition was prepared by mixing 30 grams of the epoxy resin premix of Example 1 with 30 grams of a urea-formaldehyde resin, 7 grams of a mineral black and 40 grams of barium sulfate.
• the composition was then coated onto an electronic component potting compound and cured.
• the cured coating comprised about 7.4 percent of mineral black, about 42.0 percent of barium sulfate and about 50.6 percent of epoxy and urea-formaldehyde resin binder.
• a black coating composition was prepared by mixing 30 grams of the epoxy resin premix of Example 1 with 30 grams of a urea-formaldehyde resin, 30 grams of a mineral black and 30 grams of barium sulfate.
• the composition was coated onto an electronic component potting compound and then cured.
• the cured coating comprised about 27.7 percent of the mineral black, about 27.7 percent of the barium sulfate and about 44.6 percent of the epoxy and urea-formaldehyde resin binder.
• composition contained too much black pigment that masked the image.
• a black coating composition was prepared by mixing 30 grams of the epoxy resin premix of Example 1 with 3 grams of a mineral black, 3 grams of a mineral violet pigment and 30 grams of barium sulfate.
• the composition was then coated onto an electronic component potting compound and cured.
• the cured coating comprised about 5.5 percent of the mineral black, about 55.3 percent of the barium sulfate, about 5.5 percent of the violet pigment, and about 33.6 percent of the epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation.
• a white image having excellent color and contrast was produced in the coating in the areas exposed to the laser radiation.
• Example 1 Following the procedure of Example 1 above, a coating composition was prepared by mixing 10 grams of the coating composition prepared in Example 9 above with 5 grams of a urea-formaldehyde resin.
• the composition was coated onto an electronic component potting compound and cured.
• the cured composition comprised about 3.7 percent of the mineral black, about 36.9 percent of the barium sulfate, about 3.7 percent of the violet pigment, and about 55.7 percent of the epoxy and urea-formaldehyde resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation.
• An excellent white image was produced in a very transparent black coating in the areas exposed to the laser radiation.
• a black coating composition was .prepared by mixing 40 grams of the coating composition prepared in Example 9 above with 40 grams of a urea-formaldehyde resin and 20 grams of a water-washed kaolin clay (ASP 170, Engelhard Minerals & Chemicals).
• the composition was coated onto an electronic component potting compound and then cured by heating for 2 hours at 150°C.
• the cured coating comprised about 1.9 percent of the mineral black, about 21.5 percent of the clay, about 19.6 percent of the barium sulfate, about 1.9 percent of the violet pigment, and about 55 percent of the epoxy and urea-formaldehyde resin binder.
• a white image having excellent contrast was produced in the very transparent black coating in the areas exposed to an imagewise pattern of laser radiation.
• a clear coating composition was prepared by mixing 20 grams of the epoxy resin premix prepared in Example 1 with 40 grams of a urea-formaldehyde resin, 20 grams of a water-washed kaolin clay (ASP 170), and 20 grams of barium sulfate.
• the composition was coated onto an electronic component potting compound and then cured.
• the cured coating comprised about 21.7 percent of the clay, about 21.7 percent of barium sulfate, and about 56.5 percent of the epoxy and urea-formaldehyde resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation.
• a white image having excellent contrast was produced in the transparent coating in the areas exposed to the laser radiation.
• a heat curable coating composition was prepared by mixing 40 grams of a water-washed kaolin clay (ASP 170) and 40 grams of a urea-formaldehyde resin following the procedure of Example 1 above.
• the mixture was coated onto an electronic component potting compound and heat cured.
• the coating became white upon curing.
• the cured coating comprised 50 percent clay and 50 percent urea-formaldehyde resin binder. It is believed that the index of refraction of the binder became less than that of the clay upon curing of the coating.
• a heat curable . coating composition was prepared by mixing 20 grams of the epoxy resin premix prepared in Example 1 with 40 grams of a urea-formaldehyde resin and 80 grams of a water-washed kaolin clay (ASP 170).
• the composition was coated onto an electronic component potting compound and heat cured.
• the coating became white upon curing like the coating of Example 13 above.
• the cured coating comprised about 60.5 percent of the clay and about 39.5 percent of the epoxy and urea-formaldehyde resin binder. It is believed that the index of refraction of this binder likewise became less than that of the clay upon curing of the coating.
• Two heat curable coating compositions were prepared by mixing 40 grams of the epoxy resin premix prepared in Example 1 with each of 20 grams and 30 grams of a water-washed kaolin clay (ASP 170), respectively, following the procedure of Example 1 above.
• ASP 170 water-washed kaolin clay
• Each composition was then coated onto an electronic component potting compound and cured. Both cured coatings were essentially transparent.
• the first cured coating comprised about 45.2 percent of the clay and about 54.8 percent of the epoxy resin binder.
• the second cured coating comprised about 55.3 percent of the clay and about 44.7 percent of the epoxy resin binder.
• the coated potting compounds were then exposed to an imagewise pattern of laser radiation. A very good white image was produced in the first coating and a good white image was produced in the second coating that was not as bright white as the image produced in Example 12 above.
• Example 1 Following the procedure of Example 1 above, three heat curable coating compositions were prepared by mixing 20 grams of a water-washed kaolin clay (ASP 170) and 20 grams of barium sulfate with each of 40 grams, 50 grams and 60 grams, respectively, of the epoxy resin premix prepared in Example 1 above.
• ASP 170 water-washed kaolin clay
• barium sulfate barium sulfate
• the first cured coating comprised about 31.1 percent of the clay, about 31.1 percent of the barium sulfate, and about 37.8 percent of the epoxy resin binder.
• the second cured coating comprised about 28.4 percent of the clay, about 28.4 percent of the barium sulfate, and about 43.2 percent of the epoxy resin binder.
• the third cured coating comprised about 26.2 percent of the clay, about 26.2 percent of barium sulfate, and about 47.6 percent of the epoxy resin binder.
• the three coated potting compounds were each exposed to an imagewise pattern of laser radiation.
• the white image produced in the first coating was excellent.
• the coating was very flat and not glossy.
• An excellent white image was produced in the second coating.
• An excellent white image was also produced in the third coating, although it was not quite as good as the image produced in Example 12 above.
• a heat curable coating composition was prepared by mixing 50 grams of the epoxy resin premix prepared in Example 1 with 40 grams of a water-washed kaolin clay (ASP 170).
• the composition was then coated onto an electronic component potting compound and cured.
• the cured coating was essentially transparent and comprised about 56.9 percent of the clay and about 43.1 percent of the epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation. A good white image was . produced in the coating, although it was not clear and bright.
• a heat curable coating composition was prepared by mixing 50 grams of the epoxy resin premix prepared in Example 1 with 40 grams of barium sulfate.
• the composition was coated onto an electronic component potting compound and then cured.
• the cured coating was essentially transparent and comprised about 56.9 percent of barium sulfate and about 43.1 percent of the epoxy resin binder.
• a good bright white image was produced in the coating upon exposure to an imagewise pattern of laser radiation.
• a higher energy density than that of Example 20 above was required to produce the good image when the barium sulfate was substituted for the clay.
• a heat curable coating composition was prepared by mixing 50 grams of the epoxy resin premix of Example 1 with 50 grams of a water-washed kaolin clay (ASP 170).
• the mixture was coated onto an electronic component potting compound and then heat cured.
• the cured coating was essentially transparent and comprised about 62.2 percent of the clay and about 37.8 percent of the epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation which produced very good white prints in the areas of the coating exposed to the radiation.
• a U.V. curable acrylated epoxy resin premix was prepared by mixing 18 parts of a mixture containing about 51.5 percent by weight of an acrylic U.V. curable resin, about 44.4 percent by weight of an acrylated epoxy resin, about 2.3 percent by weight of a plasticizer and about 1.7 percent by weight of an adhesion promoter with 1.5 parts of a U.V. photoinitiator.
• a U.V. curable coating composition was then prepared by mixing 50 grams of the above premix with 20 grams of a water-washed kaolin clay (ASP 170) and 20 grams of barium sulfate.
• ASP 170 water-washed kaolin clay
• the composition was then coated onto the surface of an electronic component potting compound to a wet thickness of 0.75 to 1.0 mil using a Markem Model 20A body coating apparatus.
• the coated electronic component was then conveyed under a 200 Watt/in ultraviolet lamp fixed at a distance of 2 inches above the component for a distance of 7.5 inches and a cure rate of 40 ft/min.
• the cured composition was essentially transparent and comprised about 22.2 percent of the clay, about 22.2 percent of barium sulfate, and about 55.6 percent of the acrylated epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation.
• the beam of a pulsed TEA C0 2 laser at 30 KV having a 2.5:1 reduction and an energy density of 2.5 joules/cm, 2 was attenuated by a metal imaging stencil. A fair white image was produced in the coating.
• a heat curable coating composition was prepared by mixing 50 grams of the epoxy resin premix of Example 1 with 10 grams of a urea-formaldehyde resin, 25 grams of a water-washed kaolin clay (ASP 170) and 25 grams of barium sulfate.
• the composition was coated onto a potting compound and then heat cured.
• the cured coating was essentially transparent and comprised about 27.7 percent of the clay, about 27.7 percent of barium sulfate, and about 44.6 percent of the epoxy and urea-formaldehyde resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation. A white image was produced in the areas exposed to the radiation that was poorer than the image produced in Example 17 above.
• a U.V. curable coating composition was prepared by mixing 50 grams of the acrylated epoxy resin premix of Example 23 with 15 grams of a water-washed kaolin clay (ASP 170) and 15 grams of barium sulfate.
• composition was then coated onto an electronic component potting compound and cured by exposure to U.V. radiation.
• the cured coating was essentially clear and comprised about 18.75 percent of the clay, about 18.75 percent of barium sulfate, and about 62.5 percent of the acrylated epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation. A white image was produced in the coating that did not exhibit good contrast.
• a U.V. curable premix was prepared by mixing 37.1 percent of a novolac epichlorohydrin phenol formaldehyde epoxy resin, 37.1 percent of a cycloaliphatic epoxy resin, 24.3 percent of a U.V. epoxy curative, and 1.4 percent of an adhesion promoter.
• U.V. curable coating compositions were then prepared by mixing 50 grams of the above premix, 40 grams of barium sulfate, 1 gram of a U.V. fluorescing whitener and 2 grams of a wax with each of 5 grams and 15 grams of a water-washed kaolin clay (ASP 170), respectively.
• ASP 170 water-washed kaolin clay
• the two compositions were then coated onto an electronic component potting compound and cured by exposure to U.V. radiation. Both cure coatings were essentially transparent.
• the first cured coating comprised about 5.1 percent of the clay, about 40.8 percent of barium sulfate, about 1.0 percent of the U.V. fluorescing whitener, about 2.1 percent of the wax, and about 51.0 percent of the epoxy resin binder.
• the second coating comprised about 13.9 percent of the clay, about 37.0 percent of barium sulfate," about 0.9 percent of the fluorescing whitener, about 1.9 percent of the wax, and about 46.3 percent of the epoxy resin binder.
• Each of the three compositions was coated onto an' electronic component potting compound and then cured by exposure to U.V. radiation. All of the cured coatings were essentially transparent and comprised about 11.6 percent of the clay, about 46.5 percent of barium sulfate, about 1.6 percent of the fluorescing whitener, about 1.6 percent of the wax, and about 38.7 percent of the epoxy resin binder.
• coated potting compounds were then exposed to an imagewise pattern of laser radiation. Excellent white images were produced in all three coatings.
• a U.V. curable coating composition was prepared by mixing 50 grams of the epoxy resin premix of Example 26 with 160 grams of barium sulfate. The ingredients were stirred together and passed through a three-roll mill once.
• the composition was then coated onto an electronic component potting compound and cured by exposing the coating to a 1500 Watt ultraviolet lamp at 200 Watts/in at a rate of 50 ft/min.
• the cured coating was essentially transparent and comprised about 76.2 percent of barium sulfate and about 23.8 percent of the epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation using a pulsed TEA C0 2 laser at 31 KV, a reduction of 2: and an energy density of 2.5 joules/cm. 2 .
• a grayish metallic white image was produced that was not as bright as the images produced in compositions containing both clay and barium sulfate.
• a potting compound suitable for encapsulating electronic components was prepared by mixing 25 grams of a bisphenol A glycidyl ether epoxy resin with 7.5 grams of a water-washed kaolin clay (ASP 170) and 30 grams of barium sulfate. The compound was molded and then cured. The compound comprised about 12 percent of the clay, about 48 percent barium sulfate, and about 40 percent of epoxy resin.
• the potting compound was then exposed to an imagewise pattern of laser radiation using a pulsed TEA C0 2 laser at 31 KV, a reduction of 2:1, and an energy density of 2.5 joules/em. 2 .
• a good clear white image was produced in the surface of the potting compound. Higher concentrations of the clay and barium sulfate would improve the uniformity of the image.
• a potting compound suitable for encapsulating electronic components was prepared by mixing 0.5 grams of a violet pigment with 62.5 grams of the potting compound prepared in Example 32 above. The compound was molded and then cured. The compound was violet in color and comprised about 11.9 percent of the clay, about 47.6 percent of the barium sulfate, about 0.8 percent of the violet pigment, and about 39.7 percent of the epoxy resin binder.
• the potting compound was then exposed to an imagewise pattern of laser radiation. A white image was produced in the violet compound. Contrast of the image could be improved by the addition of more clay and barium sulfate to the compound.
• a heat curable coating composition was prepared by mixing 50 grams of the epoxy resin premix of Example 1 with 15 grams of a water-washed kaolin clay (ASP 170), 60 grams of barium sulfate, 2 grams of a fluorescing whitener, and 2 grams of a polyethylene wax.
• ASP 170 water-washed kaolin clay
• the composition was then coated onto an electronic component potting compound and cured by exposure to I.R. radiation.
• the cured coating was essentially transparent and comprised about 13.7 percent of the clay, about 54.9 percent of barium sulfate, about 1.8 percent of fluorescing whitener, about 1.8 percent of the wax, and about 27.8 percent of the epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation. A clear white image was produced in the coating.
• a heat curable coating composition was prepared by mixing 50 grams of a phenolic resin premix comprising 49.7 percent of a reactive phenolic resin 49.7 percent tributyl phosphate, and 0.6 percent of a fungicide with 25 grams of a water-washed kaolin clay (ASP 170), 60 grams of barium sulfate, 2 grams of a fluorescing whitener, and 2 grams of a polyethylene wax.
• ASP 170 water-washed kaolin clay
• the composition was coated onto an electronic component potting compound and heat cured.
• the cured coating was essentially transparent and comprised about 14.4 percent of the clay, about 57.6 percent of barium sulfate, about 1.9 percent of fluorescing whitener, about 1.9 percent of the wax and about 24.2 percent of phenolic resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation. A sharp yellow image was produced in the areas of the coating exposed to the radiation.
• the phenolic resin binder changed color to yellow upon exposure to the radiation, so that the white image produced in the coating appeared yellow through the yellow binder.
• a varnish premix was prepared by mixing 16 parts by volume of a varnish solution comprising 86.8 percent of a phenol modified tung oil, 12.4 percent of carbitol acetate and 0.8 percent of an anti-skinhing agent, 0.25 part of cobalt and manganese driers and 0.5 part of a fungicide.
• an air cured coating composition was prepared by mixing 50 grams of the above premix with 15 grams of a water-washed kaolin clay (ASP 170), 60 grams of barium sulfate, 2 grams of fluorescing whitener and 2 grams of a polyethylene wax.
• ASP 170 water-washed kaolin clay
• barium sulfate barium sulfate
• fluorescing whitener 2 grams of fluorescing whitener
• the composition was then coated onto an electronic component potting compound and dried.
• the coating was essentially transparent and comprised about 12.4 percent of the clay, about 49.4 percent of barium sulfate, about 1.6 percent of fluorescing whitener, about 1.6 percent of the wax, and about 34.9 percent of varnish binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation. A light white image was produced in the coating in the areas exposed. The energy density of the laser could have been increased to improve the contrast of the image.
• a coating composition was prepared by mixing 50 grams of a 20% solution of nitrocellulose with 15 grams of a water-washed kaolin clay (ASP 170), 60 grams of barium sulfate, 2 grams of fluorescing whitener and 2 grams of a polyethylene wax.
• ASP 170 water-washed kaolin clay
• the composition was then coated onto an electronic component potting compound and dried.
• the dried coating was milky white and comprised about 16.8 percent of the clay, about 67.4 percent of barium sulfate, about 2.3 percent of fluorescing whitener, about 2.3 percent of the wax, and about 11.2 percent of nitrocellulose binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation.
• the coating was burned off in the areas exposed to the radiation.
• the coating was not transparent because the concentration of the clay and barium sulfate was so high.
• a ceramic coating composition was prepared by mixing 12 grams of a drying oil modified alkyd resin, 2 grams of a water-washed kaolin clay (ASP 170), 6 grams of barium sulfate, 10 grams of glass frit (Mason flux #10) and 4 grams of lithium fluoride using the procedure of Example 1.
• the composition was then coated onto a sheet of glass and heated to 1200°F for 3 minutes.
• the resin was completely burned off during heating of the coating.
• the coating produced was transparent and comprised about 9.1 percent of the clay, about 27.3 percent of barium sulfate, about 45.4 percent of glass and about 18.2 percent of lithium fluoride.
• the ceramic coating was then exposed to an imagewise pattern of laser radiation using a pulsed TEA C0 2 laser at 31 KV, a 2:1 reduction, and an energy density of 2.5 joules/cm. 2 .
• a white image of low contrast was produced in the ceramic'coating.
• Example 26 Following the procedure of Example 26 above, 25 grams of a calcined kaolin clay (Satintone No. 5, Engelhard Minerals & Chemicals) was mixed with 50 grams of the epoxy resin premix prepared in Example 26 using three passes through a three-roll mill. The viscosity at 80°F was 300,000 cps.
• the composition was coated by hand onto a stick of molded potting compound used for encapsulating electronic components.
• the coating was cured by exposure to U.V. radiation.
• the cured coating was essentially transparent and comprised about 33.3 percent of the calcined clay and about 66.7 percent of the epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation using a pulsed TEA C0 2 laser at 30 KV, a 2:1 reduction, and an energy density of 2.6 joules/cm. 2 .
• a white image was produced in the coating in the areas exposed to the radiation.
• a coating composition was prepared following the procedure of Example 39 above with the exception that the calcined kaolin clay was replaced with an equal amount of a water-washed kaolin clay (ASP 170).
• the viscosity of the mixture at 83°F was 66,000 cps.
• the composition was coated onto an electronic component potting compound and cured.
• the cured coating was essentially transparent and comprised about 33.3 percent of the water-washed clay and about 66.7 percent of the epoxy resin binder.
• the coated potting compound was then exposed to an imagewise pattern of laser radiation. A bright white image was produced in the areas exposed to the radiation.

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• Physics & Mathematics (AREA)
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• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Materials For Photolithography (AREA)
• Thermal Transfer Or Thermal Recording In General (AREA)
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• 1983
  • 1983-04-27 JP JP58074850A patent/JPS5938093A/ja active Pending
  • 1983-06-01 DE DE1983105406 patent/DE101797T1/de active Pending
  • 1983-06-01 EP EP83105406A patent/EP0101797A3/de not_active Withdrawn

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