WRITING BOARD AND METHOD FOR MANUFACTURING THEREOF

Abstract: A writing board (10) and method for manufacture thereof having a frame (12) molded from lightweight, inexpensive material which dimensionally changes as it ages. The method includes an aging step which permits the frame to become substantially dimensionally fixed. Thereafter a non-porous writing surface (38) is attached to the frame which is adapted to receive and display a mark from dry erase type pens. Molded integrally with the frame is a tray (22) to hold items such as dry-erase pens and erasers.

Description: WRITI G DABD AND METEiOD FOR MAtHFACTURING THEREOF This invention relates to writing boards or panel drawing boards, and more particularly to molded writing boards and methods for manufacturing thereof. It is known in the prior art to form writing boards such as panel drawing boards and slates from hard materials such as fiberboard, as is exemplified by U.S. Patent No. 2,112,762 issued March 26, 1938, to Chatfield and U.S. Patent No. 2,087,111 issued July 13, 1937,to Mayall. However, the use of fiberboard, Masonite and other hard materials results in a heavier and relatively more expensive writing board. This, in turn, detracts from the commercial use thereof, particularly for slates directed toward in-home use. As taught in U.S. Patent 2,522,351 issued September 12, 1950, to Egolf, a rigid plastic material such as polystyrene may be used. Again, however, these materials result in a heavy, relatively expensive board. It is also known in the prior art to provide writing boards with a non-porous writing surface which receives and displays dry erasable or wet erasable ink from marking pens. U.S. Patent 3,834,823 issued September 10, 1974, to Seregely et al and U.S. Patent 3,922,457 issued November 25, 1975, to Barnwell et al exemplify the dry erasable inks adapted for such use. Typically, the non-porous writing surface is embodied as a sheet of glass, ceramic or the like. How¬ ever, an inexpensive non-porous thin plastic sheet is preferred from a cost standpoint. This sheet of non- porous plastic must be supported and adhered to the frame in such a manner as to prevent the sheet from buck¬ ling, bubbling or wrinkling. Bubbling, buckling or wrinkling of the sheet forming the writing surface makes writing upon the surface difficult. The surface deforms in response to the pressure the person exerts on the pen, making the creation of a discrete mark virtually impos¬ sible. NAΥ\ " Accordingly, molded frames heretofore used to support the writing surface were constructed from high density plastics or other strong materials. in order to prevent the sheet writing surface from buckling, bubbling or wrinkling. The use of inexpensive, lightweight plas¬ tics such as styrofoam products (STYROFOAM is a Dow Chemical Company trademark for expanded cellular poly¬ styrene) for the frame of the writing board was shunned due to certain characteristics. Expanded cellular poly- styrene undergoes dimensional changes subsequent to mold¬ ing of the frame as it ages. These dimensional changes would , in turn, buckl , bubble or wrinkle the thin sheet of non-porous plastic serving as the writing surface, thereby detracting from the utility of the board. The present invention is directed toward over¬ coming one or more of the problems noted above. A method for constructing a writing board and the writing board so constructed is set forth whereby a lightweight, inexpensive material, such as expanded cellular polystyrene can be used as a substrate for the thin sheet of non-porous plastic writing surface. The writing board so constructed is substantially dimension- ally fixed and therefore supports the writing surface without causing buckling, bubbling or wrinkling. Toward this end, the writing board of the present invention is constructed by molding a light¬ weight, inexpensive material such as expanded cellular polystyrene products into a frame, the frame having a planar substrate which will function to support the writ- ing surface. After molding, the frame is aged, with or without the introduction of heat, for a period of time sufficient for the frame and its substrate to become substantially di ensionally fixed. Upon suitable aging, a thin sheet of non-porous plastic is adhered to the substrate, the sheet adapted to function as a writing surface to record written material from dry erase pens and the like. In another embodiment of the present invention, a layer of material is interposed between the writing surface and the substrate to resist damage and add opaque¬ ness to the writing surface. Accordingly, one object of the present inven¬ tion is to set forth a writing board and method for construction thereof wherein a lightweight, inexpensive frame can be used to support the writing surface, thereby lowering the overall cost of the writing board. The inex¬ pensive material is processed such that the dimensional changes as the frame ages which accompanies the use of certain lightweight materials is remedied preventing the writing surface attached thereto from bubbling, buckling or wrinkling. A further object of the present invention is to set forth a writing board having an integrally molded tray. The tray provides a convenient receptacle for pens, erasers and the like. Further objects and advantages of the present invention will become evident upon examination of the specification, drawings and claims. Fig. 1 is a- diagrammatic showing of the method for manufacturing the writing board of the present inven¬ tion; Fig. 2 is a perspective front view of the writing board manufactured by the steps of Fig. 1; Fig. 3 is a perspective rear view of the writ¬ ing board manufactured by the steps of Fig. 1; Fig. 4 is a perspective front view of the writing board of the present invention illustrating the attachment of the writing surface to the writing board frame; Fig. 5 is a perspective front view of another embodiment of the present invention showing the use of an intermediate sheet between the writing surface and the writing board frame; Fig. 6 is a partial section view taken as indicated on line 5-5 of Fig. 4; and Fig. 7 is a partial section view taken as indicated on line 7-7 of Fig. 6. Referring to Fig. 1, the method for construct¬ ing a writing board, shown generally as 10 in the draw¬ ings, according to the present invention is illustrated. The first step in the process, illustrated diagram ati- cally as box 11, is the integral molding of a writing board frame 12. The frame 12 is molded from an inexpen¬ sive, lightweight material such as a styrofoam product ("STYROFOAM" is a Dow Chemical Company trademark for ex- panded cellular polystyrene) . The molding of the frame 12 typically involves the injection of expandable beads of polystyrene into a closed mold, the injection of the beads being metered into the mold and heated by low- pressure steam. In the mold the beads of polystyrene expand into closed cells, the walls of which soften and weld together to form a cellular structure shaped by the mold. The object so molded, for example the writing board of the present invention, is oversaturated with water deposited therein by the low-pressure steam. In other words, the molded material contains a greater percentage of moisture than normal ambient conditions. As time passes, the molded writing board eventually dries as the moisture evaporates into its surroundings. The drying of the styrofoam product is accompanied by dimen¬ sional changes in all three dimensions; in length, in width, and in depth. It should be noted that while the applicant refers to the molding material as styrofoam products, it is to be understood that the invention disclosed and claimed herein encompasses the use of " any moldable material which, subsequent to molding thereof, is sub¬ jected to dimensional changes as the molded object ages. Styrofoam products, however, are preferred in that they result in an inexpensive and lightweight frame 12. A styrofoam product, having a density of about 2-10 pounds per cubic foot, is preferred. Those with a density of 4 pounds per cubic foot are particularly advantageous from weight, strength and cost standpoints. Subsequent to molding, the frame 12 of the writing board 10 along with other frames 12 so molded are stacked or otherwise positioned in a spaced relation¬ ship, as is schematically shown by box 14 of Fig. 1. The spatial relationship between the molded frames 12 is important to permit air to circulate about the frames for drying thereof. In the stacked relationship, the frames 12 are allowed to dry or "age". This permits the dimensional changes occasioned by aging of the frame to proceed until the frame has assumed substantially permanent dimensions as schematically shown by box 16 of Fig. 1. It has been found that aging of the frame 12 should be for at least seven days. If necessary, because of humid ambient conditions or to accelerate aging, the frames can be heated to a temperature of about 120-130°F. Depending upon ambient conditions , the frames 12 may be required to be aged for a period of several weeks before becoming substantially permanent in dimension. After aging, the frame 12 for the writing board 10 has attained the substantially permanent shape as exemplified in Figs. 2-5. It should be noted, how¬ ever, that the configuration of the writing board 10 illustrated in the drawings is by no means exclusive in that any desired shape of a writing board 10 is con- templated. The frame 12 as it leaves the aging step may be substantially rectangular, having a front shown generally as 18, a rear 20, and an upper tray 22. The upper tray 22 protrudes outwardly of the front 18. This provides a platform 24 for holding, for example, a marking pen 26 and a dry-erase sponge 28 as is shown in Fig. 2. Side- walls 30 on the tray 22 confine the pen 26 and sponge 28 to the platform 24. Molded within the front 18 so as to leave a narrow border 32 thereabout, is a planar, rectangular recess 34, as best shown in Fig. 4. The planar surface of the recess 34 defines a substrate 36, the purpose of which will hereinafter become evident. To complete the construction of the writing board 10, a non-porous sheet defining a writing surface 38 is adhered to the substrate 36 as is schematically shown by box 45 of Fig. 1. The sheet 38, as shown in Figs. 2, 4 and 5, is closely received into and mates with the recess 34. The recess 34 is preferably of a depth that the writing surface 38 when adhered therein is coplanar with the border 32 of the frame 12, as best shown in Fig. 5. The non-porous writing surface 38 can be glass, ceramic, porcelain, sheets of fluorinated resins such as Tefzel products (TEFZEL is a DuPont trade- mark for fluorinated resin) Saran film or ultra-high molecular weight polyethylene and melamine; however, from a cost standpoint, the writing surface is preferably a thin sheet of polypropylene. In all cases, the mater¬ ial selected for the writing surface 38 should be adapted to receive and display discrete marks from dry-erase pens and permit the marks to be removed with a cloth, sponge or the like. In other words, the surface 38 should be suitable for dry-erase applications. The adhering of the writing surface 38 to the frame 12 can be accomplished through any number of adhesives consistent with the materials used in the frame 12 and the writing surface 38. If a harder writing surface 38 is desired to resist damage by sharp objects and/or to give the writing surface 38 a more opaque, whiter color, a sheet of white polystyrene 40 may be adheringly interposed between the substrate 36 and the writing surface 38 as shown in Figs. 6 and 7. As seen in Figs. 6 and 7, the recess 34 is preferably of a depth to accommodate both the writing surface 38 and the polystyrene 40 so as to maintain the coplanar arrangement of the writing surface 38 and its surrounding frame border 32. Materials in substitute of the polystyrene 40 which add hardness and/or opaqueness to the writing surface 38 could likewise, be used. Since the frame 12 has been aged and thereby has assumed substantially permanent dimensions, the writ¬ ing surface 38 will not be subjected to buckling, bubbling or warping which would occur were aging to occur after adhering the writing surface 38 to the frame 12. Accord- ingly, the lightweight, inexpensive styrofoam product provides a suitable, flat supporting frame to mount and retain the writing surface 38 without bubbles, buckles or wrinkles. This, in turn, aesthetically enhances the writing board 10 and assures the utility thereof. ' To attach the writing board 10 to, for example, a wall in the consumer's kitchen, adhesive strips 42 may be attached to the back 20. Attachment to the wall is thereby made quick and easy merely by peeling off the protective layers on the adhesive stripe 42 and pressing the wall board 11 against the wall. Alternatively, a toothed slot 44 may be provided to hang the wall board 11 on a suitable wall bracket. While I have shown particular embodiments of the present invention, it is to be noted that it is subject to modification without departing from the scope of the invention described, illustrated and claimed herein.

Claims: CLAIMS: 1. A method for constructing a writing board comprising: molding a substrate from a material of the type which changes dimensionally as the substrate ages subsequent to the molding thereof; aging said material until said substrate assumes substantially permanent dimensions; and adhering a writing surface to said sub¬ strate, said writing surface receiving and displaying a discrete mark from a writing instrument. 2. The method described in claim 1 wherein said aging includes aging said substrate for at least 7 days. 3. The method described in claim 1 wherein said aging includes heating said substrate. 4. The method described in claim 3 wherein aging includes heating said substrate to a temperature within the range of about 120-130°F. 5. The method described in claim 1 wherein said material is expanded cellular polystyrene. 6. A writing board constructed by the process of claims 1, 2, 3, 4 or 5. 7. A method for manufacturing a writing board comprising: molding a frame having a planar substrate from a polystyrene material having a density from about 2 to 10 pounds per cubic foot, said material subjecting the planar substrate to dimensional changes with respect to time subsequent to the molding, thereof; aging said frame until said planar substrate assumes substantially permanent dimensions; and adhering a writing surface to said planar substrate, said writing surface being adapted to receive and to display a discrete mark from a writing instrument. 8. The method described in claim 6 wherein said molding includes molding a frame having a planar substrate from expanded cellular polystyrene. 9. The method of claim 8 wherein said molding includes molding a frame having a planar substrate from expanded cellular polystyrene having a density of about 4 pounds per cubic foot. 10. The method of claim 7 wherein aging in¬ cludes aging said frame for at least 7 days. 11. The method of claim 7 wherein aging further includes heating said frame to a temperature within the range of about 120-130°F. 12. A writing board manufactured according to the process of claims 10 or 11. 13. A method for constructing a writing board comprising: molding a substrate from a material of the type which changes dimensionally as the substrate ages subsequent to molding thereof; aging said substrate until said substrate assumes substantially permanent dimensions; adhering an intermediate layer to said substrate; and adhering a writing surface to said intermediate " layer, said writing surface receiving and displaying discrete marks from a writing instrument. 14. The method of claim 13 wherein said inter¬ mediate layer is polystyrene. 15. A writing board constructed according to claims 13, 14 or 15. 16. A writing board comprising: a molded frame having a planar substrate to support a writing surface; a writing surface affixed to said substrate and adapted to receive and display a discrete mark; and a tray molded integrally with said frame to retain and confine at least a writing implement for said writing surface. 17. The writing board of claim 16 wherein said frame and tray are expanded cellular polystyrene. 18. The writing board of claim 16 wherein said substrate is adapted to be used in a substantially ver- tical position and said tray is disposed above said substrate.

Inventors: BURKHALTER ROBERT E, BURKHALTER, ROBERT, E.
Applicants: SANFORD RES CO, SANFORD RESEARCH COMPANY
Application year: 1983
Main classification: B32B31
IPC codes: B32B5, B43L1