CA1115631A - Plastic embossing caul - Google Patents
Plastic embossing caulInfo
- Publication number
- CA1115631A CA1115631A CA301,454A CA301454A CA1115631A CA 1115631 A CA1115631 A CA 1115631A CA 301454 A CA301454 A CA 301454A CA 1115631 A CA1115631 A CA 1115631A
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- Prior art keywords
- caul
- panel
- wood
- textured
- assembly
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
A B S T R A C T
A plastic caul for embossing wood panels which preferably comprises a laminate of sheets of epoxy prepreg -- e.g. fiberglass webs impregnated with partially cured epoxy resin -- has been dis-covered. The caul may optionally include a metal core sheet. The embossing face of the caul contains a relief design, usually trans-ferred from a natural wood grain pattern.
To form the caul, a mold is first prepared. The mold may comprise a textured wood panel, the design surface of which has been sealed and then coated with a release agent. This treat-ment prevents the panel and future caul from sticking together.
Sheets of the epoxy prepreg are then layered onto the treated sur-face of the panel and compressed under heat and pressure conditions against it. In this manner, a relief of the textured design of the wood panel is transferred to the caul as it is further cured.
The plastic caul may then be separated from the wood panel and baked until fully cured. The configuration of the wood panel assumed in relief by the plastic caul is thus permanently maintained and the caul may be used for embossing smooth wood panels with the textured design of the panel used in making the mold.
A plastic caul for embossing wood panels which preferably comprises a laminate of sheets of epoxy prepreg -- e.g. fiberglass webs impregnated with partially cured epoxy resin -- has been dis-covered. The caul may optionally include a metal core sheet. The embossing face of the caul contains a relief design, usually trans-ferred from a natural wood grain pattern.
To form the caul, a mold is first prepared. The mold may comprise a textured wood panel, the design surface of which has been sealed and then coated with a release agent. This treat-ment prevents the panel and future caul from sticking together.
Sheets of the epoxy prepreg are then layered onto the treated sur-face of the panel and compressed under heat and pressure conditions against it. In this manner, a relief of the textured design of the wood panel is transferred to the caul as it is further cured.
The plastic caul may then be separated from the wood panel and baked until fully cured. The configuration of the wood panel assumed in relief by the plastic caul is thus permanently maintained and the caul may be used for embossing smooth wood panels with the textured design of the panel used in making the mold.
Description
lilSÇ~3~.
In order to upgrade or improve the appearance of low or undesirable quality wood panel surfaces, particularly with respect to paint adhèsion or durability, such surfaces are often covered with an overlay or resin impregnated sheet of paper. The resultant panel, however, usually has a smooth somewhat uninterest-ing appearance. It has therefore also been common ~o incorporate a texture or relief to the overlay panel surface, thereby lending a three-dimensional effect.
One method used to provide such a three-dimensional ef-fect is the machining of grooves into the surface of the panel.However, in addition to the high costs incurred in the machining operation, the grooves formed in the panel by such machining con-tain areas of exposed wood which present problems of paint dur-ability. In addition, an extensive or overall textured pattern is not provided by such machining.
Because of the shortcomings of machining, a technique whereby wood grain textures are embossed on~o wood surfaces has been preferred. In this procedure, a caul having the desired texture or design and the panel sought to be embossed are placed between the platens of a hot press. The caul and panel are com-pressed under heat and pressure, so that the panel takes on and retains the relief impression of the caul.
Heretofore cauls made of metal, generally mild steel, aluminum or nickel, have been employed in a platen press for embos-sing. These cauls are generally textured or provided with th~ de-sired configuration by one of several manufacturing techniques.
111 5~ 3 1 The most common techni~ue involves the construction of a hardened metallic master tool, from which a number of individual cauls can be fashioned from relatively softer metals by the combined appli-cation of pressure and an acid etching agent. Another method in-volves the application of an etching agent to specified areas ofa metallic surface, resulting in controlled removal of metal from the surface to produce a desired texture. Still another technique involves caul formation by electrochemical deposition of nickel onto a textured surface which has been coated with an electrically conductive primer. Lastly, there is a technique whereby a textured caul plate i5 formed by pouring molten aluminum into a suitable mold (sand casting).
It can readily be appreciated that in addition to the cost of the metal, the cost of producing a desired texture by any of the aforementioned techniques is relatively expensive. This cost of manufacturing tends to limit the number of different caul designs that a manufacturer can afford to use. This is obviously - a significant limitation when one considers the number of poten-tial designs that are available. It can also be appreciated that ~ome of the methods by which metal cauls are produced --i.e. etch-ing and casting-- often yield a less than genuine reproduction of a wood grain or other texture. Another shortcoming attendant with the commercial metal cauls currently available is that they are somewhat heavy and can be difficult to handle, especially during installation and removal from a hot press.
With the foregoing in mind, we provide in accordance with the present invention, a method for forming a plastic embossing caul comprising the steps of: a) sealing a textured wood panel by applying ~1563~
at least one coat of varnish to the surface of said panel; b) pro-viding said sealed panel with a release agent; c) placing an as-sembly comprising said sealed panel, a backing panel, and a plurality of epoxy prepreg plies in a hot press, said prepreg plies being disposed between the two panels; d) compressing said assembly under heat and pressure conditions until the prepreg plies form a laminated caul which is substantially cured and has assumed the relief configuration of the textured wood panel;
e) removing the assembly from the hot press; and f) separating the wood panels from the caul.
The plastic embossing caul of this invention comprises a plurality of sheets of epoxy prepreg cured into a laminate, one face of laminate containing a relief, usually wood grain, pattern.
In a preferred embodiment, the embossing caul further includes a metal sheet, preferably aluminum, inside the cured laminate as a reinforcing core.
Epoxy prepregs suitable for use in accordance with this invention are available commercially or may readily be made. These prepregs are thin (usually less than 1!2 inch thick) sheet~ com-posed of a fabric such as fiberglass which has been impregnated w~th epoxy resin and then partially cured to a flexible state.
Although solid, in a normal sense, they are still malleable. Also, they are self-bonding where subjected to sufficient heat to complete curing.
These sheets are preferably of a size appropriate for use in embossing conventional paneling-sized wood. This means that they (and any metal sheet included for reinforcement) are 11 1 5~ 3 ~
ordinarily essentially rectangular and planar in form with dimen-sions of at least about eight feet by four feet~ This shape and size may vary, however, with different modes of use. For example, where smaller panels are to be textured by an embossing roll, the S caul would be formed as a tube for the roller and in suitably re-duced dimensions of circumference and length.
To provide the desired rigidity and strength to the product caul, a plurality of epoxy prepreg sheets are laminated.
Although the number of sheets may vary dependent upon the stress to which the caul will subsequently be exposed, from about six to twenty sheets (preferably enough to produce a caul having a thickness of about 0.05 to 0.3 inch) are commonly employed.
Where a sheet of metal is included in the laminate, equal numbers of sheets of epoxy prepreg are usually placed on either site of the metal. Such a metal core reduces the number of prepreg plies necessary for good rigidity and also improves the thermal conductivity of the core. While bonding between the metal and prepreg sheet may be obtained simply by curing the prepreg, one or more layers of adhesive may also b~ provided to enhance the strength of the bond between these dissimilar sheet materials.
In forming the embossing caul of the subject invention, a te~tured panel surface (usually a natural wood surface) is seal-ed with one or more coats of, for example, varnish. The varnished panel is then provided with a conventional release agent such as a release coating - e.g. Vydax of DuPont, Wilmington, Delaware -and/or a release paper to prevent sticking that could occur later in the procedure. A plurality of epoxy prepreg plies is placed .. , . . , . . . . . . .. .. , . , . , . . ~, 1 ~ 5~ ~ ~
on the treated surface of the wood panel. This assembly is then compressed under heat and pressure conditions for a sufficient period of time so that the epoxy prepreg forms a caul which is at least substantially cured and which has assumed the configura-tion of the textured wood panel.
These desired curing conditions are readily obtainedin a conventional hot press. The assembly (ordinarily also in-- cluding a smooth backing panel of, for example, wood used with the textured panel to sandwich the prepreg sheets and faciLitate application of pressure) may simply be compressed. Particular conditions vary in conventional manner dependent upon the specific prepreg sought to be cured; however, they ordinarily range upward of minimums of about one hour at 320F and fifty pounds per square inch. -Following the compression step, the assembly is remDved from the hot press and the wood panels are separated from the caul which then bears a relief of the design configuration of the tex-tured wood panel. The prior application of the release agent to the textured wood panel aids in preventing sticking between the wood panel and the caul. The epoxy prepreg caul may then be baked, if not fuLly cured in the compression step. This ensures that the configuration of the textured wood panel assumed by the caul is permanently maintained.
The conditions or baking are again conventional and vary in accordance with the specific epoxy prepreg utilized. In addition, their minimums obviously depend upon the degree to which curing is effected during the compression step. Ordinarily, how-ever, it is preferred to complete curing after separation of the 11.1 5 6~ ~
caul in a distinct baking oven where the caul may be held for at least one hour and 350F.
Figure 1 is an exploded elevational cross-section of the elements used in forming an embossing caul in accordance with the method of the subject invention.
Figure 2 is an elevational view, partly broken away, of the same elements bein~ compressed in accordance with the method of the subject invention.
Figure 3 is an elevational cross-section of the em-bossing caul fbrmed in accordance with the method of the sub-ject invention.
Figure 4 is a perspective plan view of the embossing caul formed in accordance with the subject invention, said view - taken facing the textured surface of the embossing caul.
Figure 5 is an exploded elevational cross-section of the elements used in forming an embossing caul in accordance with an alternate embodiment of the method of the subject in-vention.
Figure 6 is an elevational cross-section of the em-bo~sing caul formed in accordance with said alternate embodi-ment of the method of the subject invention.
In accordance with the subject invention, a plastic caul and method for producing same are provided. Such cauls are used to upgrade or improve the appearance of low quality wood panel surfaces by embossing with a natural wood grain or other desired texture.
The wood panel surface is most desirably conventionally overlaid - i.e. covered with an adherent resin-impregnated paper.
In this case, it is the overlay that will be primarily embossed with the natural wood grain or other desired texture. Wood panel surfaces commonly upgraded in this fashion include plywood, particle board, hardboard and medium density fiberboard.
Suitable overlays for the preferred purpose of this invention are conventional. Most desirably, however, these ma-terials are those recognized as "medium density overlays" by the wood products industry. Such paper overlays consist of cellu-lose - fiber sheet or sheets containing not less than about 17 per cent resin solids for a beater-loaded sheet, or about 22 percent for an impregnated sheet, both based on the volatile free weight of resin and fiber exclusive of glueline. The typical resin type used to impregnate such sheets is thermo-~etting phenol-formaldehyde, but other resins providing equiva-lent performance with respect to durability are also acceptable.
The resin impregnated paper usually weighs not less than 58 pounds per 1,000 square feetof single face, including both resin and fiber but exclusive of glueline. After application, such materials usually measure not less than 0.012 inch in thickness.
In order to upgrade or improve the appearance of low or undesirable quality wood panel surfaces, particularly with respect to paint adhèsion or durability, such surfaces are often covered with an overlay or resin impregnated sheet of paper. The resultant panel, however, usually has a smooth somewhat uninterest-ing appearance. It has therefore also been common ~o incorporate a texture or relief to the overlay panel surface, thereby lending a three-dimensional effect.
One method used to provide such a three-dimensional ef-fect is the machining of grooves into the surface of the panel.However, in addition to the high costs incurred in the machining operation, the grooves formed in the panel by such machining con-tain areas of exposed wood which present problems of paint dur-ability. In addition, an extensive or overall textured pattern is not provided by such machining.
Because of the shortcomings of machining, a technique whereby wood grain textures are embossed on~o wood surfaces has been preferred. In this procedure, a caul having the desired texture or design and the panel sought to be embossed are placed between the platens of a hot press. The caul and panel are com-pressed under heat and pressure, so that the panel takes on and retains the relief impression of the caul.
Heretofore cauls made of metal, generally mild steel, aluminum or nickel, have been employed in a platen press for embos-sing. These cauls are generally textured or provided with th~ de-sired configuration by one of several manufacturing techniques.
111 5~ 3 1 The most common techni~ue involves the construction of a hardened metallic master tool, from which a number of individual cauls can be fashioned from relatively softer metals by the combined appli-cation of pressure and an acid etching agent. Another method in-volves the application of an etching agent to specified areas ofa metallic surface, resulting in controlled removal of metal from the surface to produce a desired texture. Still another technique involves caul formation by electrochemical deposition of nickel onto a textured surface which has been coated with an electrically conductive primer. Lastly, there is a technique whereby a textured caul plate i5 formed by pouring molten aluminum into a suitable mold (sand casting).
It can readily be appreciated that in addition to the cost of the metal, the cost of producing a desired texture by any of the aforementioned techniques is relatively expensive. This cost of manufacturing tends to limit the number of different caul designs that a manufacturer can afford to use. This is obviously - a significant limitation when one considers the number of poten-tial designs that are available. It can also be appreciated that ~ome of the methods by which metal cauls are produced --i.e. etch-ing and casting-- often yield a less than genuine reproduction of a wood grain or other texture. Another shortcoming attendant with the commercial metal cauls currently available is that they are somewhat heavy and can be difficult to handle, especially during installation and removal from a hot press.
With the foregoing in mind, we provide in accordance with the present invention, a method for forming a plastic embossing caul comprising the steps of: a) sealing a textured wood panel by applying ~1563~
at least one coat of varnish to the surface of said panel; b) pro-viding said sealed panel with a release agent; c) placing an as-sembly comprising said sealed panel, a backing panel, and a plurality of epoxy prepreg plies in a hot press, said prepreg plies being disposed between the two panels; d) compressing said assembly under heat and pressure conditions until the prepreg plies form a laminated caul which is substantially cured and has assumed the relief configuration of the textured wood panel;
e) removing the assembly from the hot press; and f) separating the wood panels from the caul.
The plastic embossing caul of this invention comprises a plurality of sheets of epoxy prepreg cured into a laminate, one face of laminate containing a relief, usually wood grain, pattern.
In a preferred embodiment, the embossing caul further includes a metal sheet, preferably aluminum, inside the cured laminate as a reinforcing core.
Epoxy prepregs suitable for use in accordance with this invention are available commercially or may readily be made. These prepregs are thin (usually less than 1!2 inch thick) sheet~ com-posed of a fabric such as fiberglass which has been impregnated w~th epoxy resin and then partially cured to a flexible state.
Although solid, in a normal sense, they are still malleable. Also, they are self-bonding where subjected to sufficient heat to complete curing.
These sheets are preferably of a size appropriate for use in embossing conventional paneling-sized wood. This means that they (and any metal sheet included for reinforcement) are 11 1 5~ 3 ~
ordinarily essentially rectangular and planar in form with dimen-sions of at least about eight feet by four feet~ This shape and size may vary, however, with different modes of use. For example, where smaller panels are to be textured by an embossing roll, the S caul would be formed as a tube for the roller and in suitably re-duced dimensions of circumference and length.
To provide the desired rigidity and strength to the product caul, a plurality of epoxy prepreg sheets are laminated.
Although the number of sheets may vary dependent upon the stress to which the caul will subsequently be exposed, from about six to twenty sheets (preferably enough to produce a caul having a thickness of about 0.05 to 0.3 inch) are commonly employed.
Where a sheet of metal is included in the laminate, equal numbers of sheets of epoxy prepreg are usually placed on either site of the metal. Such a metal core reduces the number of prepreg plies necessary for good rigidity and also improves the thermal conductivity of the core. While bonding between the metal and prepreg sheet may be obtained simply by curing the prepreg, one or more layers of adhesive may also b~ provided to enhance the strength of the bond between these dissimilar sheet materials.
In forming the embossing caul of the subject invention, a te~tured panel surface (usually a natural wood surface) is seal-ed with one or more coats of, for example, varnish. The varnished panel is then provided with a conventional release agent such as a release coating - e.g. Vydax of DuPont, Wilmington, Delaware -and/or a release paper to prevent sticking that could occur later in the procedure. A plurality of epoxy prepreg plies is placed .. , . . , . . . . . . .. .. , . , . , . . ~, 1 ~ 5~ ~ ~
on the treated surface of the wood panel. This assembly is then compressed under heat and pressure conditions for a sufficient period of time so that the epoxy prepreg forms a caul which is at least substantially cured and which has assumed the configura-tion of the textured wood panel.
These desired curing conditions are readily obtainedin a conventional hot press. The assembly (ordinarily also in-- cluding a smooth backing panel of, for example, wood used with the textured panel to sandwich the prepreg sheets and faciLitate application of pressure) may simply be compressed. Particular conditions vary in conventional manner dependent upon the specific prepreg sought to be cured; however, they ordinarily range upward of minimums of about one hour at 320F and fifty pounds per square inch. -Following the compression step, the assembly is remDved from the hot press and the wood panels are separated from the caul which then bears a relief of the design configuration of the tex-tured wood panel. The prior application of the release agent to the textured wood panel aids in preventing sticking between the wood panel and the caul. The epoxy prepreg caul may then be baked, if not fuLly cured in the compression step. This ensures that the configuration of the textured wood panel assumed by the caul is permanently maintained.
The conditions or baking are again conventional and vary in accordance with the specific epoxy prepreg utilized. In addition, their minimums obviously depend upon the degree to which curing is effected during the compression step. Ordinarily, how-ever, it is preferred to complete curing after separation of the 11.1 5 6~ ~
caul in a distinct baking oven where the caul may be held for at least one hour and 350F.
Figure 1 is an exploded elevational cross-section of the elements used in forming an embossing caul in accordance with the method of the subject invention.
Figure 2 is an elevational view, partly broken away, of the same elements bein~ compressed in accordance with the method of the subject invention.
Figure 3 is an elevational cross-section of the em-bossing caul fbrmed in accordance with the method of the sub-ject invention.
Figure 4 is a perspective plan view of the embossing caul formed in accordance with the subject invention, said view - taken facing the textured surface of the embossing caul.
Figure 5 is an exploded elevational cross-section of the elements used in forming an embossing caul in accordance with an alternate embodiment of the method of the subject in-vention.
Figure 6 is an elevational cross-section of the em-bo~sing caul formed in accordance with said alternate embodi-ment of the method of the subject invention.
In accordance with the subject invention, a plastic caul and method for producing same are provided. Such cauls are used to upgrade or improve the appearance of low quality wood panel surfaces by embossing with a natural wood grain or other desired texture.
The wood panel surface is most desirably conventionally overlaid - i.e. covered with an adherent resin-impregnated paper.
In this case, it is the overlay that will be primarily embossed with the natural wood grain or other desired texture. Wood panel surfaces commonly upgraded in this fashion include plywood, particle board, hardboard and medium density fiberboard.
Suitable overlays for the preferred purpose of this invention are conventional. Most desirably, however, these ma-terials are those recognized as "medium density overlays" by the wood products industry. Such paper overlays consist of cellu-lose - fiber sheet or sheets containing not less than about 17 per cent resin solids for a beater-loaded sheet, or about 22 percent for an impregnated sheet, both based on the volatile free weight of resin and fiber exclusive of glueline. The typical resin type used to impregnate such sheets is thermo-~etting phenol-formaldehyde, but other resins providing equiva-lent performance with respect to durability are also acceptable.
The resin impregnated paper usually weighs not less than 58 pounds per 1,000 square feetof single face, including both resin and fiber but exclusive of glueline. After application, such materials usually measure not less than 0.012 inch in thickness.
2~ Referring to Figure 1, the elements used in forming an embo~sing caul in accordance with the method of the subject invention include a wood panel 21 having textured surface 31, a smooth backing panel 23, and a plurality of epoxy prepregs 22.
Prior to the caul construction, the textured wood panel 21 (pre-ferably a one-quarter to five-eights inch plywood or hardboard panel) is sealed with one or more coats of varnish. After the varnish has dried, the textured panel 21 is coated with a con-ventional release agent which minimizes sticking problems that ~ 6 ~ ~
might otherwise occur later during the formation of the caul.
The smooth backing panel 23 is preferably a one-quarter to five-eights inch sanded plywood or hardboard panel. The plastic ma-terial 22 comprises a plurality of epoxy prepreg sheets. Two - 5 such prepreg materials that have been found to be ~uite effec-tive are Cordopreg E-293, sold by Ferro Corporation of ~orwalk, TM
Connecticut and E-712A Rov-Mat, sold by U.S. Polymeric of Stam-; . ford, Connecticut.-~ Referring to Figure 2, an assembly comprising the tex-tured wood panel 21 and a sanded wood panel 23 with epoxy prepreg 22.disposed therebetween is placed between the platens 11 and 12 of a hot press and compressed under heat and pressure conditions .
for a period of time so that the epoxy prepreg 22 forms a caul which is at least substantially cured and which has assumed the configuration of the textured panel 21. The assembly is then re-moved from the hot press, and the panels 21 and 23 are separated from the caul 22, which has textured surface 41 corresponding in relief configuration to surface 31 of panel 21.
The caul 22 may then be baked until fully cured, if neces-sary, whereby the textured surface 41 of the caul is permanentlymaintained.
Figures 3 and 4 illustrate the caul 22 produced in accordance with the subject invention It can be appreciated that because the caul 22 is formed against the surface of an actual textured wood panel, the resultant caul is a very realistic reproduction thereof, having a fine decorative relief textured wood grain design.
_g_ . , , . . , .. . ,, . , , . , .. .. . . . . . , ... .. . . . ~ . _ .. .. ~ , . .. . . . . . . .
.. .. . .. ... ... . .
In order to more fully appreciate the subject invention reference is made to the following examples of specific caul con-- structions:
An assembly comprising the following elements is placed in a hot-press: a 1/4 inch textured plywood panel, six plies of - Cordopreg E-293, and a 1/4 inch sanded plywood panel. This assembly is compressed for one hour at 320F (platen temperature) and 50 pounds per square inch. The plywood panels are then removed from the press and the caul baked and fully cured according to the following schedule: approximately one hour at a temperature on the order of 350F, approximately one hour at a temperature on the order of 375F, and approximately four hours at a temperature on the order of 400F. The intended application for this caul is for embossing medium density overlaid plywood at 300F and 200 pounds per square inch.
An assembly comprising the following elements is placed in a hot press: a 1/4 inch textured plywood panel, three plies TM
of E-712A Rov-Mat, and a 1/4 inch sanded plywood panel. The curing schedule and application for this caul are identical to those of Examp~e 1.
The methods illustrated in Examples 1 and 2 relate to the construction of what is known as a "traveling caul". A
I'traveling caul" is one which is matched with individual wood panels (plywood7 particle board, etc.) prior to hot-pressing, pre~sed against the wood panels under heat and pressure, and then separated from the wood panels (after each hot-press cycle) for - ~ -10-,, ,-j .
-t,~3~
re-use. Thicker such cauls of from about 12 to 20 plies of prepreg, however, are sufficiently more rigid to serve as "hanging" cauls as discussed below.
In an alternate method for forming the plastic caul of 5 the subject invention, the caul comprises an assembly containing an internal metal core sheet, which is preferably aluminum. This metal sheet should be of essentially the same length and width as the epoxy prepreg sheet; it is usually about 0.1 inch thick.
Plies of epoxy prepreg are ordinarily adhered to each face of the aluminum sheet. Approximately equal numbers of plies of each side of the metal core facilitate curing without warpage.
The prepreg plies may be self-bonded to the metal sheet incident to curing. Alternatively, epoxy or other suitable adhesives may improve the bond. As indicated above, Cordopreg E-293 and E-712A
TM
Rov-Mat have been found to be particularly effective epoxy prepregs.
Embossing cauls formed from such an epoxy prepreg-aluminum combination are particularly useful in forming what are known as stationary or "hanging" cauls. A "hanging" caul is one which is mechanically suspended within a hot press open-ing. In this manner of operation, t~e need for matching with and then separating the cauls from the individual wood panels for each hot press cycle is eliminated. Because typical hot press desi~ns restrict the methods availabe for suspending the caul within the press openings "hanging" cauls ordinarily have excellent stiffness at relatively high (300F. - 350F) press temperatures. Aluminum has been found to provide the structural rigidity required for "hanging" caul use.
Referring to Figures 5 and 6, the ele~ents employed in the alternate embodiment of the method of the subject invention B
, , 11.~5t~3~
are illustrated. An assembly comprising: first, the release coated textured panel 21'; second, a first set of plies of epoxy prepreg 51; third, an adhesive film 53; fourth, an aluminum sheet 52; fifth, a second adhesive film 53; sixth, a second set of plies of epoxy prepreg Sl; and seventh, a back-ing wood panel 23', is placed in a hot press (not shown). The assembly is then compressed under heat and pressure conditions until the plies of epoxy prepreg 51 are adhered to the aluminum sheet 52, forming a caul 22', which is substantially cured, and which has assumed the configuration 31' of the textured panel 21'.
The assembly is then removed from the hot press and panels 23' and 21' are separated from the caul 22'. Note in Figure 6 the caul 22' has surface 41' which ~orresponds in relief to surface 31' of textured wood panel 21'.
The caul 22' may then be baked, if required, until fully cured whereby the surface 41' is permanently maintained.
In order to better appreciate the alternate embodiment of the method of the subject invention reference is made to the following examples:
An assembly comprising the following elements is- placed in a hot press: a 1/4 inch textured plywood panel, four plies of epoxy prepreg (aordopreg E-293); one ply of film adhesive (EA-9605 ~old by Hysol Division of Dexter Corporation, Pittsburgh, Pa.); a TM
1/8 inch aluminum sheet; one ply of EA-960S, four plies of Cordopreg E-293; and 114 inch sanded plywood panel. This assembly is com-pressed at 75 pounds per square inch for one hour at 300F, followed by one hour at 350F. The plywood panels are then removed from the 11.1563~
press and the caul is baked and fully cured according to the following schedule: one hour at 375F. and four hours at 400F.
The intended use for this caul is for embossing medium density overlaid plywood at 300F. and 200 pounds per square inch.
An assembly comprising ~he following elements is placed -in a hot press: a 1/4 inch textured plywood paneli four plies of TM :, .
epoxy prepreg (Ferro É-293); a 1/8 inch sheet of aluminum metal, TM
four plies of epoxy prepreg (Ferro E-293); and a 1/4 inch panel of smooth-sanded plywood. This assembly is compressed for 1-1/2 hours at a temperature of 330F. under a pressure of 75 pounds per square inch. After separation, the caul is further cured by baking for one hour at 350F., one hour at 375F, and then four hours at 400F.
In summary the subject invention provides a new and improved caul for embossing overlaid wood surfaces with a tex-tured surface, and a method for forming said caul. The caul of the subject invention may be made from epoxy prepregs, either alone or in combination with a metal core. The cauls employing a suficient number of prepreg plies or the epoxy-prepreg-metal combination have sufficient rigidity and strength to be used as "hanging" cauls.
The various plastic caul configurations of the subject invention are all significantly less expensive to manufacture (with respect to both material used and actual processing) than metal cauls produced by aforementioned techniques. As a result of the cheaper costs, manufacturers may afford many different ,,.~
Prior to the caul construction, the textured wood panel 21 (pre-ferably a one-quarter to five-eights inch plywood or hardboard panel) is sealed with one or more coats of varnish. After the varnish has dried, the textured panel 21 is coated with a con-ventional release agent which minimizes sticking problems that ~ 6 ~ ~
might otherwise occur later during the formation of the caul.
The smooth backing panel 23 is preferably a one-quarter to five-eights inch sanded plywood or hardboard panel. The plastic ma-terial 22 comprises a plurality of epoxy prepreg sheets. Two - 5 such prepreg materials that have been found to be ~uite effec-tive are Cordopreg E-293, sold by Ferro Corporation of ~orwalk, TM
Connecticut and E-712A Rov-Mat, sold by U.S. Polymeric of Stam-; . ford, Connecticut.-~ Referring to Figure 2, an assembly comprising the tex-tured wood panel 21 and a sanded wood panel 23 with epoxy prepreg 22.disposed therebetween is placed between the platens 11 and 12 of a hot press and compressed under heat and pressure conditions .
for a period of time so that the epoxy prepreg 22 forms a caul which is at least substantially cured and which has assumed the configuration of the textured panel 21. The assembly is then re-moved from the hot press, and the panels 21 and 23 are separated from the caul 22, which has textured surface 41 corresponding in relief configuration to surface 31 of panel 21.
The caul 22 may then be baked until fully cured, if neces-sary, whereby the textured surface 41 of the caul is permanentlymaintained.
Figures 3 and 4 illustrate the caul 22 produced in accordance with the subject invention It can be appreciated that because the caul 22 is formed against the surface of an actual textured wood panel, the resultant caul is a very realistic reproduction thereof, having a fine decorative relief textured wood grain design.
_g_ . , , . . , .. . ,, . , , . , .. .. . . . . . , ... .. . . . ~ . _ .. .. ~ , . .. . . . . . . .
.. .. . .. ... ... . .
In order to more fully appreciate the subject invention reference is made to the following examples of specific caul con-- structions:
An assembly comprising the following elements is placed in a hot-press: a 1/4 inch textured plywood panel, six plies of - Cordopreg E-293, and a 1/4 inch sanded plywood panel. This assembly is compressed for one hour at 320F (platen temperature) and 50 pounds per square inch. The plywood panels are then removed from the press and the caul baked and fully cured according to the following schedule: approximately one hour at a temperature on the order of 350F, approximately one hour at a temperature on the order of 375F, and approximately four hours at a temperature on the order of 400F. The intended application for this caul is for embossing medium density overlaid plywood at 300F and 200 pounds per square inch.
An assembly comprising the following elements is placed in a hot press: a 1/4 inch textured plywood panel, three plies TM
of E-712A Rov-Mat, and a 1/4 inch sanded plywood panel. The curing schedule and application for this caul are identical to those of Examp~e 1.
The methods illustrated in Examples 1 and 2 relate to the construction of what is known as a "traveling caul". A
I'traveling caul" is one which is matched with individual wood panels (plywood7 particle board, etc.) prior to hot-pressing, pre~sed against the wood panels under heat and pressure, and then separated from the wood panels (after each hot-press cycle) for - ~ -10-,, ,-j .
-t,~3~
re-use. Thicker such cauls of from about 12 to 20 plies of prepreg, however, are sufficiently more rigid to serve as "hanging" cauls as discussed below.
In an alternate method for forming the plastic caul of 5 the subject invention, the caul comprises an assembly containing an internal metal core sheet, which is preferably aluminum. This metal sheet should be of essentially the same length and width as the epoxy prepreg sheet; it is usually about 0.1 inch thick.
Plies of epoxy prepreg are ordinarily adhered to each face of the aluminum sheet. Approximately equal numbers of plies of each side of the metal core facilitate curing without warpage.
The prepreg plies may be self-bonded to the metal sheet incident to curing. Alternatively, epoxy or other suitable adhesives may improve the bond. As indicated above, Cordopreg E-293 and E-712A
TM
Rov-Mat have been found to be particularly effective epoxy prepregs.
Embossing cauls formed from such an epoxy prepreg-aluminum combination are particularly useful in forming what are known as stationary or "hanging" cauls. A "hanging" caul is one which is mechanically suspended within a hot press open-ing. In this manner of operation, t~e need for matching with and then separating the cauls from the individual wood panels for each hot press cycle is eliminated. Because typical hot press desi~ns restrict the methods availabe for suspending the caul within the press openings "hanging" cauls ordinarily have excellent stiffness at relatively high (300F. - 350F) press temperatures. Aluminum has been found to provide the structural rigidity required for "hanging" caul use.
Referring to Figures 5 and 6, the ele~ents employed in the alternate embodiment of the method of the subject invention B
, , 11.~5t~3~
are illustrated. An assembly comprising: first, the release coated textured panel 21'; second, a first set of plies of epoxy prepreg 51; third, an adhesive film 53; fourth, an aluminum sheet 52; fifth, a second adhesive film 53; sixth, a second set of plies of epoxy prepreg Sl; and seventh, a back-ing wood panel 23', is placed in a hot press (not shown). The assembly is then compressed under heat and pressure conditions until the plies of epoxy prepreg 51 are adhered to the aluminum sheet 52, forming a caul 22', which is substantially cured, and which has assumed the configuration 31' of the textured panel 21'.
The assembly is then removed from the hot press and panels 23' and 21' are separated from the caul 22'. Note in Figure 6 the caul 22' has surface 41' which ~orresponds in relief to surface 31' of textured wood panel 21'.
The caul 22' may then be baked, if required, until fully cured whereby the surface 41' is permanently maintained.
In order to better appreciate the alternate embodiment of the method of the subject invention reference is made to the following examples:
An assembly comprising the following elements is- placed in a hot press: a 1/4 inch textured plywood panel, four plies of epoxy prepreg (aordopreg E-293); one ply of film adhesive (EA-9605 ~old by Hysol Division of Dexter Corporation, Pittsburgh, Pa.); a TM
1/8 inch aluminum sheet; one ply of EA-960S, four plies of Cordopreg E-293; and 114 inch sanded plywood panel. This assembly is com-pressed at 75 pounds per square inch for one hour at 300F, followed by one hour at 350F. The plywood panels are then removed from the 11.1563~
press and the caul is baked and fully cured according to the following schedule: one hour at 375F. and four hours at 400F.
The intended use for this caul is for embossing medium density overlaid plywood at 300F. and 200 pounds per square inch.
An assembly comprising ~he following elements is placed -in a hot press: a 1/4 inch textured plywood paneli four plies of TM :, .
epoxy prepreg (Ferro É-293); a 1/8 inch sheet of aluminum metal, TM
four plies of epoxy prepreg (Ferro E-293); and a 1/4 inch panel of smooth-sanded plywood. This assembly is compressed for 1-1/2 hours at a temperature of 330F. under a pressure of 75 pounds per square inch. After separation, the caul is further cured by baking for one hour at 350F., one hour at 375F, and then four hours at 400F.
In summary the subject invention provides a new and improved caul for embossing overlaid wood surfaces with a tex-tured surface, and a method for forming said caul. The caul of the subject invention may be made from epoxy prepregs, either alone or in combination with a metal core. The cauls employing a suficient number of prepreg plies or the epoxy-prepreg-metal combination have sufficient rigidity and strength to be used as "hanging" cauls.
The various plastic caul configurations of the subject invention are all significantly less expensive to manufacture (with respect to both material used and actual processing) than metal cauls produced by aforementioned techniques. As a result of the cheaper costs, manufacturers may afford many different ,,.~
3~
- cauls, thus exploiting the many designs that are available for use. Aside from the economic standpoint the cauls formed in accordance with the subject invention are very realistic re-productions of wood surfaces because they are formed against actual textured wood surfaces. This is in contrast with metal cauls which are formed by most techniques. In addition, all the cauls formed in accordance with the subject invention, even the plastic-metal composites, are significantly lighter than the metallic cauls currently available. This results in easier and safer handling, especially during installation and removal from a hot press.
Finally, the surface composition of the subject cauls permits them to be recycled for further use. This may be done by removing the applied texture (by sanding or similar mechani-cal means) and then reapplying a new texture design. This re-application is performed in a manner similar to the method al-ready discussed. Thus, one or more plies of epoxy prepreg sheet-ing are placéd on the smooth surface of the old caul. Then this caul assembly is re-compressed against a new textured surface in a hot press, removed and (if necessary) baked to complete curing.
In essence, therefore, the present cauls are suscept-ible to replacement of their texture-containing surface (or alter-natively, the opposite side o the caul could be provided with a new texture-containing surface). This characteristic still further increases the utility of the present cauls while reducing their cost by permitting conservation of their material through re-use.
1~1563~
Although the foregoing invention has been described chiefly in terms of fo~ming a caul having a relief texture taken from a natural wood surface, it is understood that re-liefs of other surfaces may also be made. As long as the sur-face sought to be duplicated in relief is sealed and providedwith release agent, a suitable caul may be ~ade from it. Thus, for example, plastic cauls of the present invention could be formed from metal or cast surfaces having a desirable design texture.
Having described the subject invention with reference to the presently preferred embodiments thereof, it will be ap-parent to those skilled in the art that many changes and modi-fication~ may be made without departing from the spirit of the invention. Accordingly, it is intended that all matter con-tained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
~15-
- cauls, thus exploiting the many designs that are available for use. Aside from the economic standpoint the cauls formed in accordance with the subject invention are very realistic re-productions of wood surfaces because they are formed against actual textured wood surfaces. This is in contrast with metal cauls which are formed by most techniques. In addition, all the cauls formed in accordance with the subject invention, even the plastic-metal composites, are significantly lighter than the metallic cauls currently available. This results in easier and safer handling, especially during installation and removal from a hot press.
Finally, the surface composition of the subject cauls permits them to be recycled for further use. This may be done by removing the applied texture (by sanding or similar mechani-cal means) and then reapplying a new texture design. This re-application is performed in a manner similar to the method al-ready discussed. Thus, one or more plies of epoxy prepreg sheet-ing are placéd on the smooth surface of the old caul. Then this caul assembly is re-compressed against a new textured surface in a hot press, removed and (if necessary) baked to complete curing.
In essence, therefore, the present cauls are suscept-ible to replacement of their texture-containing surface (or alter-natively, the opposite side o the caul could be provided with a new texture-containing surface). This characteristic still further increases the utility of the present cauls while reducing their cost by permitting conservation of their material through re-use.
1~1563~
Although the foregoing invention has been described chiefly in terms of fo~ming a caul having a relief texture taken from a natural wood surface, it is understood that re-liefs of other surfaces may also be made. As long as the sur-face sought to be duplicated in relief is sealed and providedwith release agent, a suitable caul may be ~ade from it. Thus, for example, plastic cauls of the present invention could be formed from metal or cast surfaces having a desirable design texture.
Having described the subject invention with reference to the presently preferred embodiments thereof, it will be ap-parent to those skilled in the art that many changes and modi-fication~ may be made without departing from the spirit of the invention. Accordingly, it is intended that all matter con-tained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
~15-
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for forming a plastic embossing caul comprising the steps of: a) sealing a textured wood panel by applying at least one coat of varnish to the surface of said panel to seal the same; b) providing said sealed panel with a release agent;
c) placing an assembly comprising said sealed panel, a backing panel, and a plurality of resinous prepreg plies in a hot press, said prepreg plies being disposed between the sealed panel and the backing panel; d) compressing said assembly under heat and pressure conditions until the prepreg plies form a laminated caul which is substantially cured and has assumed the relief configuration of the textured wood panel; e) removing the assembly from the hot press; and f) separating the sealed panel and the backing panel from the caul.
c) placing an assembly comprising said sealed panel, a backing panel, and a plurality of resinous prepreg plies in a hot press, said prepreg plies being disposed between the sealed panel and the backing panel; d) compressing said assembly under heat and pressure conditions until the prepreg plies form a laminated caul which is substantially cured and has assumed the relief configuration of the textured wood panel; e) removing the assembly from the hot press; and f) separating the sealed panel and the backing panel from the caul.
2. A method as recited in claim 1, in which the heat and pressure conditions of the compressing step comprise a minimum temperature of about 320°F and a pressure in the range of about 50 to about 75 pounds per square inch, said heat and pressure conditions being maintained for at least about one hour.
3, A method for forming a plastic caul comprising the steps of: a) sealing a textured wood panel by applying at least one coat of varnish to the surface of said panel; b) providing said sealed panel with a release agent; c) placing an assembly comprising said sealed panel, a plurality of epoxy prepreg plies, a metal sheet, a second plurality of epoxy prepreg plies, and a backing panel, in a hot press; d) compressing said assembly under heat and pressure conditions so that the plies of prepreg are adhered to the metal sheet, forming a laminated caul which is substantially cured, and has assumed the configuration of said sealed panel; e) removing the assembly from the hot press; and f) separating the sealed panel and the backing panel from the caul.
4. The method of claim 3, wherein the separated substan-tially cured caul is baked at elevated temperature, until fully cured, whereby the configuration of the textured wood panel assumed by the caul is permanently maintained.
5. A method as recited in claim 4 in which the metal is aluminum.
6. A method as recited in claim 3, 4 or 5, in which the heat and pressure conditions of the compressing step comprise the schedule of at least one hour at a temperature above about 320°F under a pressure in the range of about 50 to about 75 pounds per square inch.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US78912977A | 1977-04-20 | 1977-04-20 | |
| US789,129 | 1977-04-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1115631A true CA1115631A (en) | 1982-01-05 |
Family
ID=25146673
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA301,454A Expired CA1115631A (en) | 1977-04-20 | 1978-04-19 | Plastic embossing caul |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1115631A (en) |
-
1978
- 1978-04-19 CA CA301,454A patent/CA1115631A/en not_active Expired
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