Method for impregnating selected regions of a gas permeable blanket
United States Patent [191 Smith et al.  
 [ Apr. 8, 1975 METHOD FOR IMPREGNATING SELECTED REGIONS OF A GAS PERMEABLE BLANKET [75] Inventors: Harvell Morton Smith, Aurora.  
 Colo.; Larry Edward Howard; Harry Todd Mitchell, III, both of Richmond, Ind.; Lester Fisher, Centerville, Ind.  
 [73] Assignee: Johns-Manville Corporation,  
 Greenwood Village, C010.  
 [22] Filed: Dec. 22, 1972 [21] Appl. No.: 317,572  
 [52] US. Cl. 117/38; 117/43; 117/44; 117/119; 117/126 GB; 117/140 A [51] Int. Cl. B05c 3/20; B44d H52 [58] Field ofSearch ..117/43,44,45,48,61,119, 117/140 A, 126 GB, 38  
  FOREIGN PATENTS O&#39;R APPLICATIONS 142,019 l1/l960 U.S.S.R 117/43 Primary Examiner-William D. Martin Assistant E.\&#39;aminer.lohn H. Newsome Attorney, Agent, or FirmRobert M. Krone; John D. Lister [57] ABSTRACT The selective impregnation of a gas permeable glass fiber insulating blanket is carried out by enclosing the blanket within a gas impermeable enclosure except for the surface areas of the regions to be impregnated, applying an impregnate over the exposed surface areas and creating a partial vacuum within the enclosure to draw the impregnate into the regions to be impregnated. The degree of penetration of the impregnate into the blanket is a function of the degree of the vacuum created and the time over which the vacuum is applied. Where relatively deep penetration is desired in certain portions of a region, a partial vacuum or negative pressure zone can be created in the enclosure adjacent these portions.  
 5 Claims, 4 Drawing Figures METHOD FOR IMPREGNATING SELECTED REGIONS OF A GAS PERMEABLE BLANKET BACKGROUND OF THE INVENTION The present invention relates to a gas permeable insulating blanket which has been impregnated in selected regions and the method and apparatus for producing such a blanket.  
  Most fire retardant doors are constructed with a core of insulating media that is surrounded by a hard mate rial. The core must be capable of withstanding finishing operations such as sanding and the core must have sufficient strength and holding properties to retain hinge screws that are driven into the core and carry the weight of the door. These conventional core assemblies often Weigh in excess of 70 pounds for standard size doors.  
 OBJECTS OF THE INVENTION Consequently. it is an object of the present invention to provide a relatively light weight (e.g. pounds) conventional insulating blanket with strengthened or reinforced edges that are hard enough to provide the screw holding strength required to support a door.  
  It is a further object of the present invention to provide a method and apparatus for impregnating localized regions of an insulating blanket to produce hard wood-like machinable surfaces on the edges or other portions of the blanket. Such a blanket would have the advantage of greatly reducing the weight of the core while providing the fire retardant properties and ma chinability required for such a core.  
 BRIEF SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for producing localized impregnation of a gas permeable insulating blanket comprising: (a) enclosing the blanket, except for surfaces of regions to be impregnated, in a gas impermeable enclosure, (b) applying an impregnate over the exposed surfaces of the regions to be impregnated, and (c) creating a partial vacuum within the enclosure to draw the impregnate into the regions being impregnated.  
  The apparatus utilized comprises a pair of platens having opposed major surfaces. The platens can be moved between first and second positions. In the first position the major surfaces of the platens are adapted to clamp a blanket therebetween and in the second po sition the major surfaces are spaced apart a sufficient distance to permit the insertion and removal of blankets from the apparatus. When the platens are in the first position, the major surfaces of the platens together with side closure plates carried on one of the platens define a cavity between the platens which is adapted to receive a gas permeable blanket. When a blanket is in the cavity one of the closure plates is positioned to expose a surface of the blanket so that impregnate can be placed on the exposed surface of the blanket. When impregnate has been placed on the exposed surface, means for creating a partial vacuum within the cavity is activated to draw the impregnate into the regions of the blanket to be impregnated.  
  The above method and apparatus are utilized to impregnate localized regions of the insulating blanket with a resin so that a hard wood-like machineable surface is provided on the edges of the blanket. The remainder of the blanket remains soft, flexible and of low density.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the apparatus of the present invention;  
 FIG. 2 is a side elevational view of the apparatus platens;  
  FIG. 3 is an elevational view of the major surface of one of the platens taken substantially along lines 33 of FIG. 2; and  
  FIG. 4 is a cross sectional view through the platens with an insulating blanket in place and taken substantially along lines 44 of FIG. 1.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, the impregnating apparatus includes two platen assemblies 2&#39;0 and 22. While the illustrated assembly is one preferred form of the apparatus for carrying out the method of the present invention, it will be apparent to those of ordinary skill in the art that certain modifications can be utilized in the apparatus which are equivalent to those disclosed and illustrated.  
  The platen assemblies 20 and 22 are each provided with a metal platen 24 and 26, respectively, which are supported on hollow shafts 28 and 30. The hollow shafts 28 and 30 are each rotatably mounted on a carriage (not shown) and provided with a conventional indexing means (e.g., a ring gear on the shaft which meshs with an output gear of an electric motor affixed to the carriage) for rotating the platen assembly through intervals of The carriages are each slidably mounted in tracks and provided with double acting hydraulic piston cylinder assemblies or other conventional means for moving the platens 24 and 26 toward or away from each other. While both platens must be capable of rotation to index successive sides of the platens into position for the impregnating process. Only one of the platens needs to be reciprocally mounted to bring the platens into position for the impregnating operation and to separate the platens for the insertion and removal of insulating blankets.  
  As best shown in FIGS. 2, 3 and 4, the platens 24 and 26 have major surfaces 32 and 34 respectively which engage and clamp the insulating blanket 36 therebetween when the platens are brought into their operative position. The major surfaces 32 and 34 are provided with recesses 38 and 40 which communicate with vacuum pumps (not shown) through the hollow shafts 28 and 30 of the platen assemblies and vacuum ports 42 and 44.  
  While recesses of other configurations can be utilized, the recesses 38 and 40 are shallow and constricted at their midportions. For the platens 24 and 26 which are intended to handle elongate insulating blankets suitable for door cores, the shallow recesses 38 and 40 are elongated with constricted center portions and flaring end portions which terminate adjacent ends of the platens. The configuration of the recesses is illustrated in FIG. 3 which shows the constricted portion 46 and the flaring end portions 48 of the recess 38.  
  Due to the constricted center portions and the flaring end portions of the recesses 38 and 40, there is less insulating material between the recesses and an exposed edge of a blanket clamped in the cavity in the regions farthest from the vacuum ports 42 and 44 than there is in the regions closest to the vacuum ports. Thus, the resistance offered by the insulating blanket to the flow of air from an exposed edge is greatest where the suction is greatest, at the central portion of the recess, and gradually tapers off toward the ends where the suction is the least. In this way, the effective suction at the surface of an edge (the reduction in air pressure at the surface of an edge) is equalized along an entire edge in stead of being greatest at the midportion of an edge. Thus, the same degree of impregnate penetration is obtained all along an edge. While the recess shown in FIG. 3 is only constricted relative to the longer side edges, the recess can also be constricted in its midportion relative to the upper and lower edges. For example, if the upper and lower edges as shown in FIG. 3 were as long as or longer than the side edges shown in that Figure, it would be necessary to constrict the midportion of the recess relative to these edges to equalize the effective suction along these edges.  
  The platen 24 is provided with a series of sliding closure plates 50, 52, 54 and 56 which are located about the major surface 32 the platen and cooperate with a complementary groove 58 extending about the periphery of the major surface 40 of platen 26. The plates 50, 52, 54 and 56 are each provided with a pair of depending runners 60 which are received in complementary slots 62 located in side walls of the platen 24. The runners 60 and the slots 62 have dove tail configurations so that the slots in the side wall both guide the closure plates and provide a means for retaining the closure plates in place. The runners 60 extend from rear edges of the closure plates to about the middle of the plates. The lengths and positions of the runners plus the lengths of the slots in the side walls are coordinated so that when the plates bottom on the slot 58 in the platen 26, the runners are flush with the major surface 32 of the platens or somewhat recessed within the ends of the slots 62. While as shown the plates are slid in and out manually, it is contemplated that conventional mechanisms can be utilized to automatically slide the closure plates back and forth.  
  FIGS. 2 and 3 show auxiliary vacuum ports 64 and 66 of the present invention which are utilized to induce impregnation of localized regions of the blanket to a depth greater than surrounding regions. These auxiliary ports are particularly adapted for use with a blanket where it is desired to provide a hardened area of greater depth for the location of a door knob and lock or similar means. The auxiliary vacuum ports are located on the major surfaces 32 and 34 of the platens and are connected to an auxiliary vacuum pump. The vacuum ports 64 and 66 are arranged inwardly of a region where the greater depth of impregnation is to occur, and reduce the pressure in the region intermediate the vacuum ports and the edge of the major surface.  
  An impregnate applying apparatus 68 is provided to apply impregnate along the upper edge of an insulating blanket retained between platens 24 and 26. The applicator comprises a trough 70 which is divided by a plurality of plates 72 into sections with each section having its own impregnate supply line 74. Since the trough is divided into a plurality of sections (e.g., five sections) a particular section can supply impregnate to a specific region of an exposed edge. Thus, when it is desired to produce a localized region of greater impregnate penetration, impregnate can be poured on localized portion of the edge above that region. In the illustrated embodiment a central section 76 is offset somewhat to facilitate the application of impregnate to an edge portion of an insulating blanket where a door knob and lock would be placed. The central section 76 along with two intermediate sections 78 combine to supply the transverse edge of the blanket with impregnate. All five sections, including outer sections 80, are utilized to provide the longitudinal edge portions with impregnate. Each of the supply lines 74 to the various sections of the trough is provided with a conventional valve 82 which can be suitably actuated by conventional controls to provide a flow of impregnate to the specific sections required for a particular application of an impregnate. The impregnate assembly is mounted on a carriage (not shown) which can be moved in a vertical direction. In this manner, the trough can be located at the proper elevation for supplying impregnate to both the longitudinal and transverse edges of the blanket. In addition, the trough can be raised to permit the indexing of the platens without the platens coming into contact with the trough.  
  In operation, a blanket of gas permeable insulating material 36 e.g., fiber glass insulating material is placed in platen 24 with closure plates 52, 54 and 56 extended. The platens are then brought together so that the closure plates 52, 54 and 56 are received in the groove 58 of the platen 26 and the major surfaces of the platens grip the blanket 36 of insulating material therebetween. The impregnate is then coated over the exposed edge of the blanket by allowing the impregnate to flow from the sections 76 and 78 of the trough all along the upper edge of the blanket. Once the upper edge of the blanket is coated, the vacuum pump or pumps which communicate with recesses 38 and 40 through ports 42 and 44 are turned on and the impregnate is drawn into the insulating blanket by the vacuum created within the cavity. The degree of penetration by the impregnate is governed by the degree of the vacuum created within the cavity and the length of time the vacuum is applied. Once the impregnate has penetrated to the desired depth relative to an edge, the vacuum pump is shut off and the platens are indexed through to the next position bringing the closure plate 56 to the uppermost position. Once in this position, the closure plate 56 is slid back and the closure plate 50 is slid into the groove 58 to thereby provide an enclosure wherein only the upper edge of the blanket is exposed by the retraction of the closure plate 56. The sequence of impregnation. is thus repeated until each edge of the blanket has been impregnated. Once the impregnation of the blanket 36.  
 is completed, the platens are separated and the blanket is removed for the curing of the impregnate and the finishing of the edges.  
  When it is desired to impregnate one region of the blanket to a greater depth, the impregnate is applied from the central section 76 of the trough to the surface area of the blanket immediately above the auxiliary vacuum ports 64 and 66. The vacuum pumps for the auxiliary vacuum system are then actuated for a suffi-&#39; cient amount of time to draw the impregnate down to the desired depth. After this is completed, the remainder of the edge is coated with the impregnate and the main vacuum system is actuated to draw the impregnate into the blanket the desired depth along the entire edge. The above procedure can also be reversed with the auxiliary vacuum system being operated to draw the impregnate to a greater depth in the central region after the entire upper edge has been impregnated through the use of the main vacuum system.  
  When forming a door core a basic fiber glass insulating board of the required density (e.g., about 6 pounds/cubic foot) is produced in a conventional manner including a normal cure. The board is then cut slightly oversize and is impregnated to a depth of typically up to about an inch and three quarters by the process outlined above with a resin material. All four edges of the board and the region for the door handle and lock are impregnated. The impregnate is then cured and sanded or otherwise finished to the proper size.  
  The resin material contains both resin and a filler. The resins can be phenolic, melamine or urea resins or modifications and mixtures thereof. The fillers can in clude asbestos, powdered glass, clays and other equivalent fillers. The material can also contain certain vinyl based monomers and/or cellulosic polymers and/or certain inorganic intermediate bonding agents.  
  When using the resin materials, the above processes produce an insulating blanket having strong high density edges to a desired depth. These edges are both machineable and have the required strength to hold screws to support the door on hinges and the like. The interior of the blanket remains as a low density soft flexible insulation blanket.  
 What we claim is:  
  l. A method for producing localized impregnation of a gas permeable insulating blanket comprising:  
 a. enclosing the blanket, except for surface areas of regions to be impregnated, in a gas impermeable enclosure;  
 b. applying an impregnate over the exposed surface areas of the regions to be impregnated;  
 0. creating a partial vacuum within the enclosure to draw the impregnate into the regions to be impregnated;  
 d. applying additional impregnate to a portion of the surface areas, and  
 e. creating a partial vacuum within an isolated portion of the enclosure inward of a specific region.  
 2. A method as defined in claim 1 wherein:  
 a. the blanket is enclosed except for one edge of the blanket.  
 3. A method as defined in claim 1 wherein:  
 a the degree of penetration of the impregnate into the blanket is controlled by the degree of the vacuum created and the time the vacuum is applied.  
 4. A method for producing localized impregnation of a gas permeable insulating blanket having two major surfaces with a plurality of edges joining the major surfaces comprising:  
 a. enclosing the blanket except for a surface of one of the edges in a gas impermeable enclosure;  
 b. applying an impregnate over the exposed surface of the edge;  
 e. creating a partial vacuum within the enclosure to draw the impregnate into a portion of the blanket adjacent the edge;  
 d. repeating steps (a), (b) and (c) for at least one other edge of the blanket;  
 e. applying additional impregnate to a portion of one of the edges, and  
 f. creating a partial vacuum within an isolated portion of the enclosure inward of a specific region which includes said portion to draw the additional impregnate into the specific region.  
 5. A method as defined in claim 4 wherein:  
 a. the degree of penetration of the impregnate into the blanket is controlled by the degree of the vacuum created and the time the vacuum is applied.  
 Q UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,876,449 DATED April 8, INV ENTOR(S); H. M. Smith, et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:  
  Claim 1 (e) after &#34;region&#34; should read &#34;which includes said portion to draw the additional impregnate into the specific region&#34; Signed and Sealed this Twenty-seventh Day Of July 1976 [SEAL] Arrest:  
 RUTH c. MASON C.MARSHALL DANN Arresting Officer (ommissiuner ufPalents and Trademarks