US3131104A - Method and apparatus for applying protective coatings - Google Patents

Description

APU! 28, 1964 D. L.. KORN 3,;3J04

n/nsn'mmv AND APPARATUS ma APPLYING PROTECT-:WE coAmrGs-f Filed om. 2Q, 1960 f 21 sheets-sneer. 1

INVENTOR. DON ALD L. KORN ATTORNEY April 28y i964 D. l.. KORN 3,131,104

METHOD AND APPARATUS FOR APPLYING PROTECTIVE COATINGS Filed Oct. 20. 1960 2 Sheets-Sheet 2 INVENTOR. DONALD L. KORN ATTORNEY United States Patent C 3,131,104 METHOD AND APPARATUS FOR APPLYDIG PRTECTIVE COATINGS Donald L. Korn, Sapulpa, Ghia., assigner to Tank Seal Products Company, Sapulpa, irla., a partnership Filed Oct. 2d, 1969, Ser. No. 63,800 4 Claims. (Cl. 156-73) This invention relates to methods and apparatus for use in applying protective coatings to various materials to prevent corrosion, erosion, and the like. More particularly, this invention relates to methods and apparatus for applying protective coatings which are homogeneous and gas-free.

The oil industry is currently interested in providing protective coatings and linings for the inside of steel oil storage tanks. Due to the nature of the fluids being stored and/or galvanic corrosive action, the tanks become pitted, with possible leakage from the tank. To overcome this problem protective coatings comprising therrnosetting or thermoplasitc resins either alone or in combination with fibrous materials such as fiberglass are being used to provide a non-corrosive and non-erosive coating and lining for storage tanks and the like. However, due to the nature of the fibrous mat when combined with the resin material gas or air cavities are formed in or under the coating. Once the resin has set, this cavity becomes an anomaly to not only decrease the mechanical strength of the coating but more importantly, form a corrosive cell.

Accordingly, it is a primary object of this invention to overcome the obiections and problems associated with providing protective coatings and linings to the interior of tanks and the like.

An additional object of this invention is to provide apparatus and methods for eliminating gas or air cavities in protective coatings and linings using fibrous mats in combination with thermosetting or thermoplastic resins.

A still further object of this invention is to provide methods and apparatus for vibrating a protective coating and lining just prior to or during the time it becomes set or in a hardened condition.

A yet still further object of this invention is to provide methods and apparatus for eliminating gas or air cavities in protective coatings and linings by vibrating the apparatus being coated.

An additional object of this invention is to provide an apparatus which imparts vibratory movement to the unset or unhardened lining yet permits immediate escape of the air cavities normally tending to form in said protective coating and lining.

These and other objects of this invention will become more apparent upon further reading of the specilication, description, operation and claims of this invention when taken in conjunction with the following illustrations of which:

FIGURE l is a side elevational view partly in crosssection which described the methods and apparatus typically used in this invention.

FlGURE 2 is a partial front elevational view of the apparatus of FIGURE l.

FIGURE 3 is a front elevational partially sectional view of an apparatus forming an additional embodiment of this invention.

,l3l,llli Patented Apr. 2S, 1964i ice FIGURE 4 is a front elevational view, partly cut away and part sectional, of an additional embodiment of this invention.

FlGURE 5 is a sectional view taken along the line 5-5 of FIGURE 4.

Description Referring now to FIGURES 1 and 2 in greater detail, the numeral 1li designates the material, such as a steel tank bottom, to be coated. Typically the steel material 1li rests on ground 12. A resin 14, such as a thermosetting resin, is sprayed upon the tank bottom through nozzle i6 from supply tubing 18 and a pump and reservoir, not shown. A iibrous mat 29 is rolled over or sprayed upon the resinous coating 14. The air cavities which usually tend to form by the combined action of the viscous resin 14 and the dense fibrous material 2li is eliminated using a gas releasing cylinder of metallic or synthetic resin hardware cloth 22 or other similar screen or porous material whose ends are terminated with cylindrical end plates 24 and shaft 26 which is rotatably supported by yoke 28. An extension handle 3@ is attached to the yoke portion 28 for the convenience of the operator. An electric or pneumatic vibration unit 32 is supported at the lower end of handle 30 by straps or clamps 34. In this particular instance vibration occurs by reciprocating movement of rod 36 which is biased by springs 3S. Electrical control wires 40 from a control mechanism 42 is adapted to be positioned for operator control, usually on handle 36. Supply leads 44 from an outside source of power are directed to the control mechanism 42. Although an electrical type of vibrating unit is shown it is to be understood that a pneumatic type of vibration control may also be used and is contemplated as within the scope of this invention.

An additional embodiment of this invention is shown in FIGURE 3 wherein the hardware cloth or screen and disc-type of gas releasing cylinder unit is replaced by a grooved cylinder 46 which has appropriate V-shaped slots or grooves 43 in the periphery thereof. Similar to the device shown in FIGURES 1 and 2, the grooved cylinder i6 is adapted to be rotatingly supported by yoke 2S through a shaft, such as the bolt 26 shown. The grooves 48 permit limited mechanical contact with the resin and mat 20 yet permits escape of gas or air cavities once brought to the surface by the vibration from unit 32 placed on handle 3l).

Operation A typical operation of the apparatus and methods of this invention can best be described in relation to the application of a protective lining and coating to the inside of an oil storage tank.

Typically, the portion to be coated is dried and sand blasted to a commercial clean finish. A phosphoric acidvinyl-chromate primer material is painted or sprayed upon the sand blasted surface to condition the steel and afford a greater bonding surface for the coating. A premixed polyester resin, such as is sold by the Rohm & Haas Company under the trademark Paraplex, is sprayed upon the surface to be coated and lined. Typically, this resin is a pre-mixed unsaturated polyester solution dissolved in monomeric stryene, containing cobalt naphthenate and a thixotropic agent. The addition of a hydroperoxide catalyst such as methyl ethyl ketone peroxide promotes the cure and setting of the polyester resin. Although the above resin hase been described as preferred, it is to be understood and to be within the scope of this invention that other resins such as the epoxy resins or other types of thermosetting and/or thermoplastic resins can be and are used with the apparatus and methods of this invention. Typically the resin is pre-mixed and has sufficient pot life that it can be used without danger of premature setting. An appropriate pump and storage reservoir system, not shown, is used to pump the resin through supply line l and nozzle 16 Where it is atomized and sprayed, usually in the amount of twenty (20) square feet per gallon of resin, to form a layer of uncured and unset resin. A fibrous mat is placed over the resin and pressed thereinto such that the resin intermingles among the fibers of the mat. Typically, the mat of this invention is produced by cutting continuous strands of fiberglass into two inch lengths which are thereafter deposited in a random pattern in the form of a continuous length of a firm bonded mat. The mat comes in standard Widths up to fifty and sixty inches and in lengths running anywhere from one hundred fifty feet to five hundred feet depending on the weight per square foot required. Typical of the type of mat used in this invention is that manufactured by the Ferro Corporation under the trademark HSB. Uniformat A high solubility binder such as powdered polyester resin is used in forming a temporary bond of the random fiber pattern. The powdered resin binder is partially soluble in the stryene component f the polyester resin, above described. When the mat is placed upon the resin layer which has been previously deposited the mat becomes impregnated or wetted with the resin. The bonding strength of the mat is reduced by the solubility of the powdered resin in the stryene which gives the mat the ability to drape around curves and conform to the general shape of the tank material as exposed. This drapability of the material permits reasonable configuration without loss of strength continuity in the product. The mat preferably is of the type within the range of three-fourths ounce to three ounces per square foot. Other types of matting material may be used in performing the method and apparatus of this invention, such as that used in matched metal dye molding typically veils, tapes, structural mats and unidirectional fiber mats. In those instances where the surface is fairly uniform, smooth, etc., woven or patterned roving or other Woven fiberglass fabrics may be used.

The shape, size, and density of the mat in combination with the viscous resin is such that it is highly susceptible to trapping air bubbles thereunder. In order to combine the rolling out, wetting and removal of air cavities within the resin, the apparatus of this invention is used. The vibratory movement provided by vibrator 32 acting through handle 30 and yoke 28 is carried to the hardware cloth cylinder 22 through the shaft, and end plate 24 to provide a combined rolling and vibratory movement to the resin and fiber system. The entrapped air cavities pass upward and are released through the spaces formed by the screen or hardware cloth 22 to the atmosphere. In addition, improved wetting of the fibrous material with the resin is accomplished for a firm, compact and high strength protective coating. In some instances, either prior to or after the main protective coating, additional layers of resin and fibrousy mat may be placed over the tank or set resin and mat 2i) as required for the particular surface.

The frequency of vibration from vibrator 32 is controlled electrically or pneumatically at control unit 42 by the operator. The working frequency will vary primarily in relation to the viscosity of the combined resin and fibrous mat. This may range from zero cycles per second up to and including beyond the sonic range. In some instances the object is Vibrated While using the roller of this invention.

It is to be understood that the apparatus of this invention which includes the vibrating screen unit and roller can be used with other types of protective coating methods and materials. For example, an apparatus presently available for coating surfaces includes opposed movable nozzles which are emitting streams of polyester resin, one stream from a supply of resin plus cobalt naphthenate the other including resin plus MBK peroxide catalyst. In between is an electric cutter that ejects chopped strands of fiberglass which meets with the liquid resin streams to be deposited on a mold or on a surface to be coated. The nature of the system however, is such that it picks up quantities of air from the various injection and nozzle systems. The vibrating apparatus of this invention is required to be used to smooth and roll out the coating and eliminate the air cavities which may form.

The embodiment of FIGURES 4 and 5 represent an additional feature of this invention for use in applying protective coatings such as the random matting and polyester resin as heretofore described. Shaft 26 is non-rotatively attached to yoke 2S and handle 30 to which is attached the vibration unit, not shown in these views, but heretofore described. The roller unit includes cylindrical end plates 24, to which is attached screen (hardware cloth, eg.) 22 forming a cylindrical unit adapted to roll about shaft 26 at bearing sleeves 4i-9. Interiorly and longitudinally of the cylindrical screen is a rubber or plastic squeegee member Si) preferrably rigidly attached to shaft 26 using clamping members 52 such that the member 50 will assume a position approximately to the coating. Squeegee member 5t) is formed with beveled edges 54 at its lower extremity longitudinally adjacent the inner periphery of screen 22. In one embodiment the squeegee will contact screen 22 to Wipe excess resin therefrom. In the preferred operation, after fibrous matting and resin have been positioned on the material to be coated, the roller is moved along the top surface. The weight of the screen and roller plus the vibratory motion imparted thereto causes air or gas bubbles which tend to form Within the coating to be released. Simultaneous therewith the squeegee 50, which maintains substantially the position shown, is adapted to move excess resin ahead of the roller movement and thus provide a homogeneous coating of substantially constant thickness. Additionally, the vibrating motion is more efiiciently coupled with the unset resin and mat coating to eliminate gas or air pockets. In the instance where clamps 52 form a rigid connection with shaft 26, rather than an alternate method whereby the squeefiee 50 hangs as a pendulum, reversing the handle 30 and yoke 28 by turning over, places the seueegee up and out of position. In that instance the apparatus becomes essentially that described in FIGURES l and 2. A plurality of squeegee members are to be angularly displaced about shaft 26 such that various positions of the handle and yoke maintains at least one squeegee in operative position, i.e., about 90 to the unset coating.

Although the invention has been described with reference to specific and preferred embodiments, it will be apparent, however, that many modiiications can be made without departing from the spirit of the invention. For example, the vibration unit 32 may he combined or unitized with the handle, yoke or within the roller to effect the vibrator movement. Additionaily the application is not necessarily limited to coating processes but also the molding processes using high strength fibrous materials and viscous resins where gas or air has a tendency to be entrapped therein. Accordingly this invention should be construed not to be limited to the embodiment herein described, but should be limited only by the scope of the appended claims.

What is claimed is:

1. A method of applying viscous and fibrous coatings to objects comprising the steps of applying a relatively viscous synthetic resin to said object, wetting a fibrous material in said resin, moving a gas releasing roller over said combined resin and material, and vibrating said roller simultaneously during said moving.

2. A method of applying viscous and fibrous coatings to clean objects comprising the steps of applying a relatively viscous settable resin to said object, placing a brous material Within said resin, moving a gas releasing roller over said combined resin and material, forcing excess of said resin ahead of said roller, and vibrating said roller simultaneously during said moving.

3. Apparatus for removing gas cavities from a protective coating of unset relatively viscous polyester resin combined with temporarily bonded random pattern iiberglass mat comprising, a longitudinal handle, a yoke attached to said handle, a gas transudable cylindrical roller rotatably attached to said yoke for movement along said 15 unset coating, means attached to said handle to cause vibratory motion of said roller and means Ito `control the amplitude and frequency of said motion.

4. Apparatus according to claim 3 wherein a squeegee member is longitudinally and nou-rotatively attached interiorly of said cylindrical member at an angle substantially 90 to said unset coating.

References Cited in the tile of this patent UNITED STATES PATENTS 1,325,124 Midgley Mar. 30, 1920 1,955,101 Sloan Apr. 17, 1934 2,944,543 Newcombe July 12, 1960 FOREIGN PATENTS 511,099 Great Britain Aug. 14, 1939

Claims (1)

1. A METHOD OF APPLYING VISCOUS AND FIBROUS COATINGS TO OBJECTS COMPRISING THE STEPS OF APPLYING A RELATIVELY VISCOUS SYNTHETIC RESIN TO SAID OBJECT, WETTING A FIBROUS MATERIAL IN SAID RESIN, MOVING A GAS RELEASING ROLLER OVER

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