US3707062A

US3707062A - Field application of thermosetting resin

Info

Publication number: US3707062A
Application number: US7954A
Authority: US
Inventors: Fleetwood B Joiner Jr
Original assignee: FLEETWOOD B JOINER JR
Current assignee: FLEETWOOD B JOINER JR
Priority date: 1970-02-02
Filing date: 1970-02-02
Publication date: 1972-12-26
Anticipated expiration: 1989-12-26

Abstract

A method for on-site building construction using thermosetting resin and means for electrically setting the resin substantially instantaneously to provide structurally sound joints is disclosed. The method permits the use of thermosetting resins under adverse conditions of temperature and environment.

Description

United States Patent Joiner, Jr.

1 51 3,707,062 Dec.26,1972

[54] FIELD APPLICATION OF THERMOSETTING RESIN [72] Inventor: Fleetwood B. Joiner, Jr., 703 North Bayfront, Balboa Island, Calif. 92662 [22] Filed: Feb. 2, 1970 [21] Appl. No.: 7,954

52 US. (:1. ..52/741,52/173,52/309, 287/189.36 A 511 1111. C1 ..E04b l/58, E04b 1/60 [58] Field 61 Search ..52/127, 173, 309, 741; 264/27; 287/189.36 A

[56] References Cited UNITED STATES PATENTS 1,460,941 7/1923 Broughton ..52/495 X 1,678,504 7/1928 Glover ..52/495 X 2,378,801 6/1945 Sidell et al. ..52/309 X 2,497,657 2/1950 Cole ..46 31 3,111,569 11/1963 Rubenstein... ..s2/232 x 3,258,888 7/1966 Lum ..s2/309 x 3,263,268 8/1966 Flaherty ..264 27 3,415,028 12/1968 Nerem ..52/309 x 3,492,381 1/1970 Rhyne ..264/27 FOREIGN PATENTS OR APPLlCATlONS 680,240 2/1964 Canada .52 309 605,964 8/1948 Great Britain ..287/189.36 A

Primary Examiner-Alfred C. Perham Attorney-Fowler, Knobbe & Martens [57] ABSTRACT A method for on-site building construction using thermosetting-resin and means for electrically setting the resin substantially instantaneously to provide structurally sound joints is disclosed. The method permits the use of thermosetting resins under adverse conditions of temperature and environment.

2 Claims, 7 Drawing Figures PATENTED m2 3.707.062

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' FIELD APPLICATION OF THERMOSETTING RESIN RELATED APPLICATION Application Ser. No. 881,949 filed Dec. 4, 1969, for BUILDING CONSTRUCTION UTILIZING PINNED PANELS, by Fleetwood B. Joiner.

This invention relates to the construction of static structures such as dwelling houses, industrial and commercial buildings. The invention relates in a more specific manner to a method for on-site construction of load bearing structural components of buildings using thermosetting resin.

Glues of various types, including thermosetting resins, have gained wide acceptance in the fabrication of components and assemblies where structural strength is of secondary importance or the resin can be maintained under controlled conditions of temperature and environment during hardening or setting. Thermoplastic and fusible materials have been used in a variety of applications to form seals. Thermoplastic materials generally have insufficient bonding strength for use in load bearing constructions or where structural strength requirements are significant. Thermoplastic and thermosetting materials have heretofore been unsuitable for use in on site construction of buildings and, in spite of the advantages thermoplastics possess in terms of flexibility, pre-formability, etc., neither thermosetting nor thermoplastic resins meet building code requirements for load bearing structural units.

The bonding strength of thermosetting resins generally and particularly of epoxy resins, certain polyester resins, etc., have been recognized and such thermosetting resins can be used in the prefabrication of certain modules or other structural units for subsequent use in the construction of a building, under circumstances such that-the setting conditions for the resin can be controlled. Field applied thermosetting resins, however, are unacceptable under building codes for the bonding load bearing units of a building. The use of thermosetting resins in a reinforcing member, such as a cable, to rigidify the reinforcing member in which the resin is set by electrically applied heat has been proposed but the prior art presents no satisfactory -means or methods for overcoming the difficulties in and obstacles to the use of thermosetting resins in onsite building construction.

A method is provided, according to the process of this invention, whereby the convenience and economic advantages of field application of adhesively bonded joints are obtainable. Such advantages could not heretofore be obtained because adhesive joints formed in the field were not acceptable under building codes, since such joints could not be relied upon to have the necessary bonding strength.

According to this invention, a building is constructed by arranging building units in the configuration of at least a part of the building such that edges of the building units are adjacent to each other. These edges are then joined using the novel techniques described herein. These techniques include the placing of a layer of thermosetting resin adhesive between the edges of the building units, placing an electrical conductor along the layer of resin such that heat produced by the conductor is applied to the resin, and producing an 0 mosetting resins practical in the field construction of buildings, a result which could not heretofore be accornplished. I

The electrical conductor can be placed along the resin to provide electrically produced heat in the resin in a number of ways. The most direct method for placing the conductor in heat conductive relation with the resin is to embed one or more electric wires along the adhesive layer in contact with the resin. Electricity is then applied to the wire to produce the necessary heat in the adhesive joint to set the thermosetting resin quickly and reliably.

According to one particular feature of the invention, the step of placing the electrical conductor along the resin layer comprises the inclusion of at least one electrically conductive building unit as a part of the joint. to be formed. This is advantageous in certain building constructions in that it avoids the necessity for the additional step of placing a wire along the adhesive joint.-

According to another particularly advantageous feature of the invention, the placing .of the electrical c'onductor along the resin layer comprises the step of including a material in the resin which makes the adhesive layer electrically conductive. Electricity is then simply applied to the adhesive layer to produce the heat necessary to set the'resin substantially instantaneously. Heat may be electrically produced in the resin by direct connection of the electrical conductor to a source of direct or alternating current 'or by inducing electricity into the conductor indirectly.

Building codes generally forbid the use of adhesive resins in on-site building construction. This rule .is relaxed in certain instances where the entire glue line is visible and available for inspection. The use of resin bonded elements in structural units, however, has not been feasible where the structural units are required to bear substantial loads. According to a principle feature of this invention, these disadvantages are overcome and on-site use of adhesive resins in load bearing structural units is made possible.

According to one feature of thisv invention, a complete or substantially complete building may be assembled by the arrangement of building units, the joints being initially formed by placing a layer of resin adhesive between the edges of the various building units. When the building is substantially completely assembled, using temporary bracing if necessary, then electricity is applied to the adhesive joints throughout the entire building simultaneously, or to the various major elements of the building individually, to set the resin substantially instantaneously. By careful placement of the conductors, and application of the electrically produced heat to the resin, an entire building can be bonded to form one integral load bearing structure. This building technique is especially applicable to the construction of buildings according to the principles set forth in my copending application Ser. No. 881,949,

or bolt steel structural members together in a construction of a building in the field. This is time consuming and expensive. According to one of the features of thisinvention, structural steel or other structural metal units are bonded together by the substantially instantaneous setting of thermosetting resin adhesives.

The various advantages and features of the invention are similarly applicable to building structures which are constructed in part of steel or other metal building elements.

These and other features will become apparent from the specification which follows and from the drawing to which reference is made, it being understood that the drawings and illustrations are intended only to exemplify the invention and not to limit the applicability of the structures, methods and techniques described herein.

FIG. 1 is a perspective view showing the application of the inventive process to the construction of an integrally bonded building using the principles described and claimed in my aforesaid copending patent applicatron.

FIG. 2 is an enlarged view showing one method for forming the adhesive joint of this invention.

FIG. 3 illustrates an alternative method for forming the adhesive joint of this invention.

FIG. 4 is a perspective view of a corner joint formed according to the principles of this invention and FIG. 5 is a horizontal section of the corner joint illustrated in FIG. 4 taken substantially along lines 55 of FIG. 4.

FIG. 6 is a perspective view of a joint formed of structural steel using the techniques of this invention and FIG. 7 is a vertical section of the joint illustrated in FIG. 6 taken substantially along lines 7-7 of FIG. 6.

Reference is made to FIG. 1 which illustrates a preferred and especially advantageous application of the method of this invention. According to this feature and application of the invention, a building is constructed using the techniques and concepts described in my aforesaid copending patent application and the method for forming joints which constitutes a principal feature of this invention. a

An integrally bonded building, part of which is shown at 10, is constructed using the elements described in my copending patent application and illustrated in abbreviated form in FIG. 1. The floor of the building 12 may be formed, for example, of a plurality of floor panel units 14, 14a, 14b, ,etc. The load bearing walls 16 are constructed according to this feature of the invention utilizing pinned panels as more fully described and claimed in my aforesaid copending patent application.

Reference is made to said patent application for a complete discussion of the concepts and constructions involving the utilization of pinned panels for building constructions. Briefly, however, a building is constructed according to the principles set forth in my aforesaid patent application by constructing load bearing walls from panels which are so composed and constructed as alone to be incapable of supporting any substantial vertical load, such as imposed by a permanent roof, second story, etc. These normally non-load bearing panels are pinned for at. least three-fifths their height. The pinning may be accomplished by like or similar panels joined to form corners such as illustrated at 18, 20, 22, 24, and 26 in FIG. 1. These corners may be single corners as shown at 18, for example, or double comers as shown at 20, for example. A great many corner configurations are, of course, possible without departing from the scope of the inventive concept. The panels may also be pinned by using vertical shaft elements which may be in the form of non-load bearing pins secured along the vertical edge of a panel, or door or window jambs, etc. The pinning elements should encompass at least the center three-fifths of the height of the panelto be pinned. The reader is referred to my copending patent application for a complete discussion of the concepts and advantages of building construction using pinned panels. 4

The roof 32 of the building may be of any desired construction but, according to the present invention, is advantageously composed of a plurality of roof panels 34, 36, etc.

The pinned panel units, along with other building elements, are assembled in the configuration of a complete or substantially complete building or building module, the edges of the building units being joined with a thermosetting resin adhesive. If temperature and other environmental conditions were ideal, the building could be assembled as described and simply maintained in the proper configuration during normal setting of the resin. Even under ideal conditions, however, this technique of building construction suffers from certain very serious drawbacks.

For example, serious difficulties may be faced even if the building is to be constructed on-site on a hot, dry summer day, these conditions being desirable to form a strong thermoset adhesive bond. If the thermosetting resin used as the joining adhesive is formulated to have a short pot life, then the resin will begin setting as each individual joint is formed and during the formation of subsequent joints the previously formed resin joints will be disturbed. The disturbance of a partially set resin joint is likely to result in a completely set resin adhesive joint which is not structurally sound and may not even be weather tight.

On the other hand, if the thermosetting resin is compounded to have a long pot life, the building can be assembled substantially completely before any significant setting of the resin begins. In this case, however, the conditions necessary for satisfactory setting of the resin are not likely to prevail for a sufficiently long time to form bonded joints having adequate structural strength so as to form a load bearing building or building module.

These disadvantages are overcome according to the present invention by placing an electrical conductor along the adhesive layers. In the embodiment illustrated in FIG. 1,

electrical conductors

38, 40, 42 and 44, which may be wires or cables, are placed along the top and bottoms of the walls in one direction. Similar conductors, exemplified at 46 and 48, are placed along the tops and bottoms of the walls in the other direction and a conductor 50 may be placed along the roof line of the building. Electricity may be applied from a single source or from a plurality of isolated sources as indicated by the polarity illustrated in FIG. 1.

By appropriate connection of the conductors to a single source or to plural isolated sources, the entire building, or building module can be completely or substantially assembled using a thermosetting resin of adequate pot life. Once the building is assembled, electricity is applied to all of the conductors. This simultaneously sets-all or at least a majority of the structural joints in the building to form an integral load bearing structure. Such a structure has greater strength, load bearing capacity and rigidity than a similar structure in which the individual building units are joined separately.

It is pointed out that the placement of the conductors in the embodiment illustrated in FIG. 1 is merely illustrative of the placement of conductors along adhesive layerjoints and is not intended as an exhaustive illustration of the placement of all conductors in a building. Obviously, the placement of conductors in a given building will depend upon the number of load bearing walls and relative placement of the load bearing walls in the building. Non-load bearing walls may be joined according to the techniques of this invention also, but non-load bearing wall joints can satisfactorily be formed using thermosetting resins without the need of the instantaneous setting techniques described herein.

FIG. 2 illustrates in greater detail the construction of building joints according to this invention and the process for forming such joints. This exemplary building joint may be in a building of the type constructed according to the process described in my aforesaid copending patent application, although I do not limit my invention to the formation of joints in that type of building.

A panel 52 may, for example, be joined along a vertical edge 54, a top edge 56 and a bottom edge 58. The vertical edge is joined to a pinning member, another panel, or another vertical element of any desired type or configuration. The top edge is joined to a plate 60 which, in the illustrative embodiment, is morticed to receive the top edge of the panel. The bottom edge is joined to a floor 62.

According to the process of this invention, an adhesive layer 64 is placed along the vertical edge 54 of the panel 52, and, similarly,-adhesive layer 66 is placed along the top edge 56 and adhesive layer 68 is placed along the bottom edge 58 of the panel 52. Conductor 70 is placed along the adhesive layer 66 and conductor 72 is placed along the adhesive layer 68. A separate conductor may be placed along the adhesive layer 64 as well but, as will be discussed, this is usually not necessary.

Once the edges of the building elements are joined with the adhesive layer, then electric energy is applied to the

conductors

70 and 72. This electrically heats the adhesive resin layers 66 and 68 to form substantially instantaneously a thermoset cured adhesive bond between the panel edges and the adjacent edges of the other building units. This setting of the resin layers 66 and 68 begins the polymerization process which tends to follow up the adhesive layer 64 from the bottom layer 68 and down the adhesive layer 64 from the top layer 66. Thus, instantaneous thermosetting of resin layer 64 is accomplished even though-no conductor is directly in contact therewith. Even if the vertical joint resin layer 64 is very long, the ends of the vertical joint can be set thus fixing the relative positions of the vertical members to permit completion of the setting of the vertical joint. Additional setting of the vertical joint can be accomplished by the method illustrated in FIG. 3, if required.

Depending upon the particular building being constructed, the technique as just described may be satisfactory. However, for relatively long lengths of resin, setting of the resin layer 64 may require that an additional conductor be placed as previously described. Complete setting of this resin may also be accomplished by associating a conductor with this adhesive layer by adding a material to the resin during compounding to make the resin electrically conductive. By appropriate polarity application, electricityis conducted from the conductor to the conductor 72 through the adhesive layer, thereby substantially instantaneously setting the resin in layer 64. The

layers

66 and 68 may also be made electrically conductive this way in lieu of or in addition to the placing of the

conductor

70 and 72 therealong.

An alternative method for producing an electric current in the conductor is illustrated in FIG. 3 in which a panel 74 is joined to a panel 76 by a thermosetting adhesive resin layer 78 which, in a preferred embodiment may include metal flakes or powder, aluminum fillers, for example, to render the adhesive conductive. The panels may be bonded in like manner to the plate 80. According to this embodiment of the invention an electrical induction device 82 is passed along the joint to electrically induce current in the conductor in the resin. Actually, the same technique may be used to induce electricity in a conductor such as a wire or a plurality of wires which are laid along the layer of adhesive but since this method of producing electricity in the conductor is somewhat less efficient than direct application of electrical voltage to the conductor, the latter technique is preferred.

Induction heating of conductors is a well known technique and the reader is referred to electrical engineering texts and the electrical engineering art generally for a discussion of the equipment and the techniques used in the application of this process. Generally speaking, sufficient heating of the conductor associated with the adhesive resin can be accomplished using frequencies from 60 to 600 cycles per second although frequencies from 60 cycles per second to 1,000 kilocycles or higher may be used effectively. Optimum frequency will depend upon the type of conductor used and the thickness of the joint being formed. The inductor device 82 includes an induction coil. The flow of current in the coil produces a magnetic field or flux which surrounds each turn of the coil. This flux passes through the air and through any conductor that is near the coil. Each reversal or alternation of the current causes the flux in the conductor to change. The change of flux induces a voltage in the conductor which forces large eddy currents to flow through the conductor. These induced currents produce heat in the conductor which sets the resin.

It is also possible to set the resin in a joint, for example adhesive layer 78, without the inclusion of a conductor by the use of dielectric heating. Dielectric heat transfer is somewhat less efficient than the methods of heating previously described and the equipment for producing dielectric heat is expensive and complex. The previous techniques are, therefore, preferred but if non-conductive resin is preferred or required in a particular installation, dielectric heating of the resin layer is highly advantageous in that it assures a substantially instantaneous set of the resin thus assuring a strong structuralbond. Dielectric heating requires frequencies from about I megacycle to 50 megacycles or higher. The very rapid reversal of the electric field surrounding the dielectric heater distorts and agitates the molecular structure of the resin such that internal molecular friction generates heat uniformly through all parts, of the resin thereby causing the thermosetting resin to set. Again, the reader is referred to the electrical engineering art for details concerning the equipment suitable for dielectric heating. Specific reference is made to Chute, ELECTRONICS IN INDUSTRY, Second Edition, McGraw-I-Iill, I956, and the references cited therein.

In the embodiments discussed hereinbefore, an electrical conductor was placed in association with the adhesive layer for the sole purpose of electrically heating the layer to set the resin. FIGS. 4 and 5 illustrate in simplified form the utilization of the techniques of this invention wherein electrically conductive structural components are utilized as conductors for setting the resin in the formation of the adhesive bond. In the illustrative embodiment of FIGS. 4 and 5, three

panels

84, 86 and 88 are arranged with their edges adjacent each other. A layer of adhesive, indicated generally at 90 of suitable configuration is placed along the edges of the panels. An electrically

conductive molding

92 and 94 is placed at the intersection of the panels. The molding in this illustration is shown as an angle member which may be composed of iron, aluminum, magnesium, or any other conductive material. It may, forexample, be made of a decorative polymer which has aluminum, brass, or other metal flake therein to make the molding at least semi-conductive. The molding may, of course, be in any desired configuration. Once the panels and molding are in the proper arrangement relative to each other, electric energy is applied to the moldings to electrically heat the resin adjacent thereto. a

The panels may be conductive but also may be nonconductive panels such as plywood, fiberboard, or a composite of building materials. In one embodiment of the invention, the resin -is made partially conductive, for example, by the inclusion of flake aluminum in the resin during compounding, and electricity is caused to flow from the molding 90 through the resin to the molding 94 for producing a bonded thermoset adhesive resin joint.

Adhesively bonded joints of this type are quite suitable for the formation of load bearing walls and other structures in a building. Thermosetting resins applied according to the techniques of the prior art could under ideal temperature and atmospheric conditions form load bearing structurally sound joints but the builder could not rely upon the formation of structurally sound thermoset resin joints and the only way to determine whether the joint was sufficiently bonded was, in effect, to destroy the very joint which was to be tested.

FIGS. 6 and 7 illustrate a further application of the broad concept of this invention. In this application, a joint indicated generally at of, for example, vertical I-

beams

102 and 104 and horizontal I-

beams

106 and 108 is formed of a single unitary resin bond indicated generally at 110. In addition to the I-beam elements of the joint, angle braces 112 and 114 strengthen-the joint between the I-beam 104 and l-

beams

106 and 108 and angle braces-116 and 118 likewise strengthen the joint between I-beam 102 and l-

beams

106 and 108. A scab 120, on one side of l-

beams

106 and 108 and a like scab on the other side may also be included to provide additional strength to the joint.

In the embodiment of the invention illustrated, an adhesive layer is placed between the edges and/or faces of the elements of the joint to be bonded.

together. In the particular joint illustrated, the adhesive layer is continuous and follows the general configuration of the intersecting elements but this is not necessary to the invention. Once the elements of the joint are in place and the adhesive layer has been placed therebetween, then electricity is applied to the respective I-beams, for example. Electricity may be applied,

,for example, between I-

beams

106 and 108 and/or between I-

beams

102 and 104 to provide electrical heating of the intersection. This substantially instantaneously sets the resin forminga structurally sound adhesive bond. This permits the assembly of the joint using the liquid resin and setting of the resin in one relatively simple step. This permits easier alignment of the elements, forms a joint 4 of exceptionally high strength and is less expensive and more efficient than the techniques of the prior art. v

An I-beam joint is illustrated but, of course, structural metal elements of steel, aluminum, etc. of any desired configuration may be bonded utilizing the methods and techniques of the invention as described.

FIG. 7 illustrates one application of the method and structural system of this invention. According to this feature of the invention, the structural elements are provided with mating dowels and apertures, shown at 122 and 124, which add to the structural strength and rigidity of the building unit. The dowels are received in corresponding apertures and bonded therein by means of the resin layer 110, when the resin layer is set by the application of electricity.

The term instantaneous setting, and variations thereof, as used herein means the very rapid setting of the resin under the influence of relatively high temperatures producible only by application of artificial heat to the resin. The actual setting time is a function of the resin type and, more directly, of the particular resin formulation. Setting times, as contemplated in this invention may be as little as several seconds to as long as several minutes, both times being much shorter than to thermosetting adhesives. Phenolic resins, phenol formaldehyde, for example, and urea formaldehyde resins may be used according to the present invention but by far the most useful and most advantageous class of thermosetting resin adhesives are the epoxy resins. Epoxy resins are characterized by having reactive oxirane rings in the resin structure. They are commonly supplied in both, liquid and solid form. In use, these epoxides are either homopolymerized with the aid of catalysts or copolymerized with hardeners such as polyamines, polyamides and anhydrides. Epoxy resins can be formulated having very short or relatively long pot lives and may include fillers and extenders, some of which may be conductive so as to form-a conductor in association with the resin layer. Epoxy resins are well known and the techniques for manufacturing and handling these resins to achieve the desired strength, adhesive, and pot lifecharacteristics are well known in the polymerization art.

Certain cross-linked polyesters form adhesive resin joints of satisfactory strength and may be set using the techniques of this invention. Curing, of the polyester resin is initiated by the addition of a catalyst along with activators to promote the cross-linking reaction such that the cure can be effected by the application of high temperatures for comparatively short times. Cobalt naphthanate is a common promoter but many other promoters and catalysts are available. Inhibitors may be added to the resin formulation to provide initial resin stability and, along with the catalysts, promoters, etc. to regulate the pot life and set time for cure. The considerations are known to those skilled in the polymerization art and no extended discussion is warranted. The reader is referred to the polymerization art generally for the practical and theoretical considerations involved in selecting appropriate thermosetting resins and to the particular manufacturers use manuals and instructions for detailed information relative to the use of a particular resin. Thermosetting resins of this type are commercially available from many suppliers.

The use of thermosetting resins in on-site building construction in the field, using the techniques of this invention, results in building constructions and buildings involving the novel combination of building units, adhesive layers and conductors. These techniques provide means for using thermosetting resins in an environment and application which has not heretofore been possible. Moreover, the buildings constructed according to the principles of this invention possess greater strength and rigidity than buildings constructed according to the principles and practices of the prior art. In addition to these advantages and improvements in the building structure, as compared with the prior art, the techniques of the process described herein permit more economical construction of residential, business and commercial buildings.

As previously pointed out, the techniques of this invention find the greatest economical advantage in the construction of buildings according to the techniques and principles described and claimed in my aforesaid patent application using pinned panels, but the techniques of this invention are not limited to the construction of such buildings and, likewise, are not limited to the specific embodiment as disclosed herein.

Modifications and adaptations of the techniques discussed and the structures discussed and illustrated maybe made by those skilled in the art based upon the teachings herein without departing from the spirit and scope of the claims which follow.

What is claimed is:

l. The method of bonding load-bearing metal structural building elements together which comprises joining said elements with a layer of thermosetting resin adhesive at the building site under field environmental conditions and electrically heating said metal to thereby heat resin to substantially instantaneously set said resin to form an integrally bonded joint between said building elements.

2. The method as described in claim 1 wherein the building elements comprise mating dowel pins and apertures, the dowel pins being secured in the apertures by the resin adhesive upon electrical heating.