WO1998049404A1

WO1998049404A1 - Coating composition and method

Info

Publication number: WO1998049404A1
Application number: PCT/US1998/008705
Authority: WO
Inventors: Roger Keith Barker; Richard Henry Butler
Original assignee: Infraliner Systems, Inc.
Priority date: 1997-05-01
Filing date: 1998-04-30
Publication date: 1998-11-05
Also published as: US5996304A; AU7364598A

Abstract

A blend of bonding polyester resin with an acid resistant polyester resin and heat dispersant filler to provide a liner to preserve, protect and/or restore concrete (2) and other structural surfaces which are subjected to acidic environments. A core or structural layer of a composite of polymer (9) and milled fiberglass (10) can be included for badly deteriorated surfaces in need of increased structural strength. The blend can also be used in combination with aggregate milled fiberglass to be extruded or molded into articles which are substituents for conventional concrete. An apparatus (3) for applying the composites to the structural layer is also included. The blend may be highly filled and spray applied (3b) to masonry surfaces (2) and used in combination with plug material and fabric to successfully patch leaking cavities in said masonry surfaces.

Description

COATING COMPOSITION and METHOD

Field of the Invention

This invention relates to polymeric coating compositions for preserving, protecting, and/or restoring substrate structural surfaces such as concrete, masonry, steel, roofing, and similar materials. The composition may also be used as a supporting matrix for molded or extruded products which can replace or be substituted for traditional concrete products. In one specific aspect, the invention relates to a method for applying the protective coating to concrete surfaces such as those found in either new or deteriorated manholes, lifting stations and piping which will be or have been exposed to acidic corrosion. In a more general aspect, the invention relates to a polymeric coating system useful in preventing corrosion and leakage in storage and naval vessels and in conducting passageways for chemicals, waste water, sea water, and petroleum products .

Background of the Invention

The protection of construction materials from the corrosive effects of chemicals in the environment has always received a great deal of attention from not only the designers of buildings, dams, piers, hydraulic systems, and storage vessels but also from the owners who want low maintenance structures and systems that remain in operating condition for long periods of time. Coatings, liners, paints, and various surface treatments have all been employed with varying degrees of success, and any chipping, cracking, pinholes, or delamination in the coatings or liners usually leads to rapid deterioration of the underlying surface . Perhaps the most widely used construction material today, other than wood, is concrete and this is in part due to its cost, formability, and its resistance to adverse conditions. Among the adverse conditions which give the most challenge to designers of concrete structures are those conditions encountered in the handling of waste water and sewerage.

While concrete is widely used in waste water collection and treatment facilities, it is subject to significant corrosive attack when exposed, unprotected, to sulfide generation in waste water. Sources of sulfides in waste water include unregulated industrial discharges, degradation of sulfur-containing organic material, and the microbiological reduction of other forms of sulfur. Urban development and the construction of regional collection and treatment centers has increased waste water travel time in collection systems which consequently increases the opportunity for sulfide generation.

Hydrogen sulfide is a major portion of the odor associated with manholes and waste treatment facilities and it is toxic and corrosive. For concrete, the corrosion process begins with the oxidation of hydrogen sulfide to sulfuric acid. The acid subsequently reacts with the limestone based cement binder in the concrete thus weakening the surface structure leading to the deterioration of manholes, lift stations, and other exposed concrete surfaces . In the past, a number of solutions to the problem of concrete corrosion have been sought . One early attempt employed vitrified clay liners, but these proved unsatisfactory. More recently, many epoxy coatings have been tested but these tend to fail wherever exposure to significant sulfuric acid attack occurs. Perhaps the most satisfactory protective system developed so far has been the application of pre-formed polyvinyl chloride (PVC) liners to concrete surfaces during construction. While this solution may hold promise for some new concrete construction, there are drawbacks such as handling and properly aligning the PVC sections, sealing the seams, the cost of sufficiently rigid and large diameter PVC structures, and the lack of a water-tight bond between the PVC liner and the underlying concrete which provides space for moisture and condensation to collect.

Furthermore, there is yet to be found any clear cut satisfactory method or materials for rehabilitating existing corroded concrete surfaces, particularly manholes. The current practice of coring out a manhole, inserting a PVC liner, and filling the resulting cavity between the liner and cored out wall with concrete grout has not proven to be a satisfactory solution as the grout tends to crack, become filled with moisture, and allow movement of the liner, requiring additional costly repair.

Another problem in rehabilitation efforts is that these projects do not readily allow for down time, so that conventional concrete surface repair using cement cannot easily take place. Thus, one object of the present invention is to devise a coating that bonds to concrete even while wet and provides protection from sulfuric and other acids.

While bonding coatings and liners have been used in the past, one of the problems is applying the coating so there are no cracks or pinholes. It is through these pinholes that acid can penetrate into the underlying concrete surface. Thus, it is another object of the present invention to provide a concrete liner which is resistant to pinhole and crack formation.

In a report entitled "Evaluation of Protective Coatings for Concrete" by John A Redner, et al . of the County Sanitation District of Los Angeles County, Wittier, California dated February 1995, it is concluded that: "To survive, the coating not only has to be acid proof and able to bond to the concrete substrate, but it also has to be applicator friendly. " Therefore, it is still another object of the present invention to provide a composition which can be readily and successfully applied to concrete surfaces under varying conditions and with a high rate of success.

In the above report by Redner, et al . , the known concrete coatings were placed in the following categories: coal tar, coal tar mortar, concrete sealer, epoxy, epoxy mortar, liner, phenolic, polyester, polyester mortar, polyurea, silicone, specialty concrete, urethane, vinyl ester, and vinyl ester mortar. None of these proved satisfactory in all aspects.

It is, thus, yet another object of the present invention to provide for the application of polyester resin blended in a unique manner not previously employed and to achieve a degree of success not previously available with polymeric resins .

An especially important object is to provide a method and means for applying polyester or other resins by spraying techniques which could not heretofore be successfully accomplished. One reason why such an application could not be successful was that such resin mixes were filled only up to about 10% by volume with filler as it was difficult to spray with greater amounts. It is then another object to provide a means and method to apply a highly loaded cross-linking resin, e.g., one that is up to 50% and more filler.

It is still another object of the present invention to provide a concrete liner which can be applied to a concrete surface having an acidic or basic surface, i.e. a pH which is either greater or less than 7. One further object of the present invention is to provide a binder matrix into which aggregate or reinforcing material can be added in order to form molded, extruded, or cast articles which are substitutes for conventional concrete. The foregoing and other objects are achieved by the present invention which is described below.

Summary- of the Invention

It has, surprisingly, been found that a liner resin composition comprising a unique blend of a polymeric bonding resin having superior adhesive and elongation properties with an acid resistant polymer and a heat dispersant filler, when cured and applied to a prepared substrate, will achieve the objects mentioned above. In another aspect of the invention, it has been found that to rehabilitate badly deteriorated surfaces an orthophthalic polymer can be mixed with milled fiberglass and fumed silica to add a core or structural layer that provides strength to the coated surface structure . A unique method and means for applying the core layer within a manhole or lift station is also part of the invention.

Another discovery is that a polyester bonding resin, hereinafter described, adheres surprisingly well to a damp or wet concrete or a masonry surface when the resin is in a temperature range of about 55°F (13°C) to about 98°F (36°C) , and about 0.75% to about 1.5% benzoyl peroxide is employed as the initiator. It was particularly unexpected that this resin would serve as a bonding resin and would, in addition to readily adhering to the concrete as well as the liner coating, actually penetrate into the concrete and reinforce the concrete which forms the wall surface . It is also an important aspect of the present invention that when a polymeric resin, particularly a polyester resin is highly filled with a filler such as kaolin clay or ground fiberglass or both as hereinafter specified, that the heat of cross-linking, or curing, of the resin will be rapidly transferred to the substrate or concrete wall surface, and, as the resin is applied, no post-application shrinkage and cracking will occur because significant heat dissipation has already occurred. More particularly, in one aspect, the present invention is a composition useful in forming a coating for substrate surfaces and for forming molded structures wherein the composition comprises, before it is reacted or cross-linked, a blend having a major portion of a thixotropic, isophthalic, unsaturated polyester resin and a minor portion of a non- thixotropic, unsaturated polyester resin; a filler preferably comprising a kaolin clay, mixed with said blend, said filler comprising 30% to 70% by volume of the mixture; a catalyst; and an initiator. Preferably, the catalyst is cobalt or dimethylaniline and the initiator is methyl ethyl ketone peroxide or benzoyl peroxide .

In another aspect, the present invention is a lined concrete structure comprising a concrete wall surface; a coating layer directly bonded to said surface, said coating layer being a non-thixotropic, unsaturated polyester resin; and a liner layer directly bonded to the coating layer, the liner comprising a cured blend of a non-thixotropic, unsaturated polyester resin; a thixotropic, isophthalic unsaturated polyester resin and a kaolin clay or ground fiberglass. In a further aspect, the present invention is a method for preserving and protecting a concrete surface comprising the steps of cleaning the concrete surface to remove loose materials and reveal and uncover the un-deteriorated surface; and, after cleaning, preferably leaving the surface in a wet or damp condition; applying a coating to said wet surface, the coating comprising non-thixotropic unsaturated polyester resin; and, mixing a blend of non-thixotropic, unsaturated polyester resin with a thixotropic isophthalic unsaturated polyester resin, a catalyst, and a filler; combining an initiator into said blend to initiate curing; and, applying said combined blend directly to said coating thereby providing a lined, protective concrete surface .

In another aspect, the present invention is a molded or extruded article which comprises the liner resin blend mentioned above as a binder matrix to which aggregate or reinforcing material is added prior to curing. Molded and extruded articles of many useful types may be thus formed. In addition, the liner resin is useful in making patches on leaking wall cavities using a fabric patch and cavity plugging material.

Further, it has also been surprisingly discovered that the system of the bonding resin and liner resin will bond to a steel substrate making it a protective coating for steel piping and storage vessels both above and underground either on the inside and outside of the vessel or pipe. This is particularly helpful for oil and gasoline storage tanks and for many chemicals.

Brief Description of the Drawings

The novel features that are considered characteristic of the present invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

Figure 1 is- a block flow diagram illustrating the sequence of steps that comprise a method of the present invention;

Figure 2 is a schematic representation of a segment of a manhole wall onto which the liner composition according to the present invention is being applied by spraying; Figure 3 represents a section of a concrete wall having a surface to which the bonding layer and liner layer have been applied according to the present invention;

Figure 4 shows a culvert pipe which is a product made from the composition of the subject invention with aggregate added. Such a product can be made by molding or extrusion;

Figure 5 is a schematic cross-section representation of a preferred spraying apparatus for applying the structural or core layer inside a manhole or lift station; and,

Figure 6 is a representation of the arrangement of the means for suspending and moving the apparatus of Figure 5 within a manhole to coat the walls thereof.

Detailed Description

It is an unexpected result of the invention that a coating composition comprising a unique blend of two polyester resins with a filler can be bonded to either a new or deteriorated concrete wall surface and provide a liner which is acid resistant, free of pinholes, and relatively easy to install in a permanent fashion. In the prior art, other cured, thermosetting polyester compounds are disclosed in U.S. Patent No. 3,091,936 granted June 4, 1963 to Lundbey, et . al . , and the use of fillers is disclosed in U.S. Patent No. 3,371,712 to Adams on March 5, 1968. U.S. Patent No. 3,713,297 to Hochback on January 30, 1973 discloses a mixture of unsaturated polyesters with gypsum and moist soil to produce cured structures. None of these, however, disclose the unique advantages and features of invention disclosed herein.

The method of the present invention begins by cleaning the concrete wall surface with a pressure spray of water. Manual cleaning may be also employed and should be thorough enough to uncover the un-deteriorated, hard wall surface which is to be the substrate upon which the coating and liner are to be applied. After all deteriorated matter is removed there is a final rinsing, and the wall is left damp or wet. The bonding resin is then applied. This resin has been selected because it will readily adhere to a wet concrete surface and will exhibit resiliency and elongation after having been applied. The preferred bonding resin also penetrates and "locks into" the concrete surface. After application, the bonding resin preferably has a tacky surface. After the bonding resin is applied, the liner is applied. The liner comprises a blend of the bonding resin with an acid resistant resin. This blend is mixed with a filler and then the mixture is combined with a catalyst. This mixture is applied by means of a sprayer and, in the sprayer chamber immediately before the mixture is sprayed, an initiator is added or injected into the mixture so that the resulting liner composition is cured as it is sprayed on to the tacky bonding resin. The sprayer applies the mixture uniformly and, as it cures and hardens, it provides an acid resistant surface which is pinhole free and crack resistant. Furthermore, the ability of the bonding layer to lock into the concrete and undergo a measure of elongation or shear elongate prevents delamination between the liner and the bonding resin as the liner is applied and hardens. The bonding layer secures the liner and since each layer has a polymer in common there tends to be mixing at and across the interface to provide an even greater resistance to delamination. This also provides resistance to subsequent rupture due to temperature changes and minor earth movements such as settling.

The foregoing method can be used for both new concrete surfaces and to rehabilitate aged, corroded, deteriorated concrete surfaces or for masonry surfaces. In some instances, it may be necessary to patch deep crevasses with mortar in a badly deteriorated surface, but the method of the present invention can then be used to install the liner on such surfaces. The liner is not only useful for manholes but can also be used for collection or lift stations which are employed in sewerage systems and can be applied to the interior surface of large diameter collection pipes.

It has also been surprisingly discovered that the liner resin mixture mentioned above can be used in the production of concrete substitutes by mixing it with aggregates and sand. The combined mixture can be cast or molded or formed by other techniques into numerous products.

To further appreciate the invention in the detailed description that follows, reference should be made to the following definitions which are not limiting on the invention bur are presented by way of illustration:

"Bonding" resin as used herein means a polymeric resin capable of adherence to wet concrete surfaces, and when applied to said surfaces will be resilient and will be able to undergo substantial elongation without rupture, up to 20% or more. A particular group of resins which meet these requirements are pre- promoted, low viscosity, highly resilient, non-thixotropic, unsaturated polyester resins. A specifically useful and preferred resin of this type is a resin sold by Alpha/Owens- Corning of Collierville, Tenn. and designated "ALTEK-52-563 " . The "ALTEK-52-563 " is available for room temperature curing using benzoyl peroxide depending upon selection of catalyst. It is useful for applications requiring toughness and high impact strength, and the manufacturer states that the product may be used for thin polymer concrete overlays on certain bridge structures. Another resin of this general type is Polylite 95-70 from Reichholdt of Germany. The bonding coating resin may also be a blend of resins, such as a blend of both the ALTEK-52-563 mentioned above and the E-704 mentioned below. The specifically preferred resin ALTEK-52-563 from Owens-Corning which is a orthophthalic polyester resin which is preferably available with silicon coupling agents and employs benzoyl peroxide as the preferred initiator; and, an alternate resin is ALTEK-52-561M which is preferably cured with methyl ethyl ketone peroxide. This resin is particularly useful for wet and damp condition.

"Core" or "structural" layers may be formed from orthophthalic polymers such as 52-563 from Alpha/Owens-Corning which includes silicon coupling agents. These resins can form a structural or putty-like coating when thickened appropriately with fumed silica as a thixotropic agent and used with a fiber glass filler.

"Acid resistant" resin as used herein means a resin which is resistant to attack by both weak and strong acids. Generally, these will include the isophthalic resins. A preferred and specifically useful resin is a promoted, thixotropic, isophthalic type, unsaturated polyester resin designated as "E-704 Resin" which is sold by Owens-Corning Fiberglass Corporation. Data from the manufacturer identifies this resin as having long term resistance to acidic attack, particularly to sulphuric acid. A modified version of E-704 is available which is a blend of the aforementioned polyester resin and a vinyl resin such as polyvinyl chloride. Up to 75% polyvinyl chloride may be blended with the E-704 resin.

"Filler" as used herein means an inert additive which has the capability of dispersing or transferring heat. Particularly useful are clays, particularly, the aluminum silicates known as kaolin clays. Specifically preferred is a clay designated as "Burgess KE" clay manufactured by Burgess Pigment Company of Sandersville, Georgia. In addition, a particularly preferred filler is ground or milled fiberglass from Owens-Corning.

"Catalyst" as used herein has the common meaning of a substance which causes or accelerates a chemical reaction when added to the reactants in miner amounts. Specifically preferred are cobalt and cobalt compounds such as cobalt salts for use with the methyl ethyl ketone peroxide initiator and demethylaniline for use with benzoyl peroxide initiators.

"Initiator" as used herein means an agent which causes a cross-linking or curing reaction to begin. A specifically preferred initiator is benzoyl peroxide or dibenzoyl peroxide (DBP) . Methyl ethyl ketone peroxide (MEKP) is also a useful initiator with polyester resins.

"Sprayer" as used herein means a sprayer capable of pumping and spraying from a reservoir a resin mix which begins curing while spraying. A useful sprayer is the Venus Gussmer Pro Series internal catalyst mix airless spray system (VGAS) . The sprayer nozzle may be equipped with an air knife or curtain means to guide, shape, and direct the resin mix spray. However, it is preferred that a nozzle design be used so that pressure changes or throttling effects do not cause premature cross-linking and, hence, so that clogging does not occur. "Masonry surface" as used herein includes a brick and mortar surface or a surface of concrete or cinder block and mortar.

"Thickening agent" or agent to impart thixotropy generally means a fumed silica or similar agent. Turning now to the drawings, Figure 1 shows the steps of the process in a flow diagram. After the surface, which may be concrete or other substrates, has been cleaned and pressure washed to remove loose particles and expose the firm substrate surface, the surface is rinsed with water and then air blown to remove any water accumulation. If any patching of the surface is needed then it is performed at this step.

It should be noted that the application of the bonding coat to a wet concrete surface is temperature dependent . The ambient conditions and the surface and underlying concrete should not be at a temperature where, upon a change in temperature of the concrete, significant quantities of water vapor will be released from the concrete and either prevent complete "locking" or "bonding" of the bonding resin into the concrete surface or even break existing bonds. The bonding coating is now applied with a preferred coating being a polyester resin of the type mentioned above. This application can be by painting, sponging, rolling, or spraying. The optimum or preferred method is to spray with a Venus Gussmer sprayer or similar equipment which internally injects the initiator. This surface is allowed to become tacky which takes 5 to 20 minutes depending upon air temperature, substrate temperature and humidity. The thickness of the applied bonding layer should be from about 5 mils to about 30 mils and this will depend upon the surface of the substrate, that is, if the substrate will require a thicker coating to penetrate and cover all of the small cavities that may be present. In the situation when the surface needs rebuilding, the core layer, as described herein, can be interposed and applied to the bonding coat. The core or structured layer has four times the strength of concrete. Thus, a 1/4" core layer will be able to replace 1" of concrete.

Next, the liner resin is prepared by combining in a shear mixer, such as a Banberry Mixer, the bonding resin with the acid resistant resin. Preferably, the acid resistant resin will represent about 75% of the two-resin blend although the percentage of the acid resistant resin can be as high as 90%. The blend of the two resins is then combined with the filler, preferably kaolin clay, which would typically represent 60% of the volume with the blend. A table of the preferred ranges is set forth below: Table 1

Constituent Volume Percentage Acid Resistant Resin 66% to 10%

Bonding Resin 4% to 20%

Kaolin 30% to 70%

The particular mixes and percentages selected will depend upon the particular substrate being coated, but a particularly preferred volume percentage is about 28% acid resistant resin, about 12% bonding resin, and about 60% kaolin clay or milled fiberglass or a blend of kaolin and fiberglass. After being mixed, the liner resin at this stage is in a paste form which may be stored for further use .

After the liner resin blend is prepared, it is combined with an aniline catalyst in an amount up to 2% by volume and then combined with benzoyl peroxide in an amount of about 1.5% by volume which initiates the chemical cross linking reaction that causes the liner resin to commence hardening. As used herein, the terms "cross linking" and "curing" will be used interchangeably as the reaction initiated by the peroxide is a cross-linking reaction to cross link the molecular chains of the polymers which, in the preferred case, are polyesters. The addition of cobalt or other appropriate catalysts increases the reaction speed and affects the amount of initiator required. The initiator can also be called a cross-linking agent or curing compound. Thus, depending on external conditions such as heat or humidity it may be desirable to either speed up or slow down the reaction rate. The completion of the cross linking process changes the polymer to a thermosetting polymer making it virtually insoluble, and by including an isophthalic resin, the thermosetting polymer blend becomes highly acid resistant making it a very suitable and satisfactory liner for acidic environments .

Still referring to Figure 1, but also looking at Figure 2 for the next step in the process, in Figure 2 a concrete wall section (1) of a manhole having a cleaned and prepared surface (2) to be coated is schematically represented. At this point, the concrete surface (2) has been coated with the bonding resin mentioned above. Sprayer (3) is fed by supply line (4) from reservoir (5) of liner resin prepared according to the above steps. Injected into the sprayer (3) at this point will be the initiator or peroxide through supply line (6) from reservoir (7) to combine with the blend and begin the cross linking process which is an exothermic reaction. The particular selection of an internal catalyst type of sprayer is vital in this regard because a cross linking reaction cannot begin earlier in the process or pumping difficulties and clogging will develop as the cross linking reaction begins, nor can it satisfactorily begin later by injecting it into the resin stream in air immediately after the resin leaves the nozzle as is done in some prior art processes. The point at which to preferably initiate the reaction is near the exit of and within the reaction chamber (3a) prior to exiting as a spray through the nozzle (3b) . Pressure drop needs to be controlled in the nozzle to avoid clogging. This process and the unique combination of resin properties allows the heavily filled liner resin mix to be successfully applied by spraying.

While the description of the preferred process provides that the liner resin is applied to the bonding resin which has already been applied to a surface, in certain instances the bonding layer can be dispensed with and the liner resin applied directly to the surface.

Referring again to both Figures 1 and 2, at this stage in the process the resulting product will, in a schematic representation, appear as wall section (8) as shown in Figure 3, wherein the concrete wall (11) with bonding resin layer (10) adhered thereto and the liner resin (9) is permanently bonded onto the surface of layer (10) . Since the liner resin mix includes the resin of the bonding layer (10) and is applied to the tacky surface, an exceptionally delamination-resistant liner system is achieved. The resilience of the bonding layer (10) is an important factor here as with thermal expansion and contraction of the concrete wall . The bonding layer is able to expand and stretch and elongate and yet remain firmly adhered to the wall and at the same time remain bonded to the liner (9) .

If it is desired that the liner resin be applied to a surface by means other than spraying, the initiator can be mixed into the liner resin in a drum immediately before it is painted or rolled or sponged onto a substrate, or over the bonding resin layer.

The liner resin, when properly applied, is waterproof, acid resistant, and structurally superior in many respects to the properties of the underlying concrete or other substrate and adheres and bonds to many substrates and types of concretes. It can be cast or poured, or may be used under water. By adding aggregate, sand, and reinforcement, the fabrication of building materials which are traditionally concrete can also be accomplished. The liner resin of the present invention may be used in products which include pipes, manholes, structural members, blocks, wall panels, pilings, culverts, and, in general, substitutes for concrete such as in foundations, walkways, and roads. It is especially useful in marine environments as a substitute for concrete and other structural materials.

In manufacturing such building materials, the liner resin is first combined with aggregates and sand and the cobalt and initiator are added prior to pouring or pumping. The fraction of liner resin by volume may range from 25% to 100%, depending on the desired properties such as strength and durability. The drying time or curing time can be controlled by modifying the amount of initiator and catalyst. An especially strong and useful product results when recycled fiberglass is added to the mix. The examples below provide further and better understanding of the invention. The quantities of ingredients are expressed in terms of volume percentage rather than weight as the resins as they come from the manufacturer in drums are used in volume measure as also with the other ingredients.

Example I

A concrete wall surface was coated with the E-704 resin identified hereinabove as an acid resistant polymer. Benzoyl peroxide was used as the initiator. After curing, the hardened resin was readily stripped from the wall surfaces and did not appear to exhibit useful adhesion.

Example II

The ALTEK 52-563 polyester bonding resin was blended with the E-704 resin with benzoyl peroxide initiator and applied to a concrete wall surface and allowed to cure and harden.

Manual removal proved difficult but some shrinkage and a tendency towards brittleness and cracking was observed.

Example III

A filler of kaolin clay with aluminum silicate surfacing was added to the blend of the two polyester resins of Example II and applied to a concrete wall surface. Cracking appeared eliminated. It is thought that the heat transfer characteristics of the kaolin cause the heat to be dispersed as the curing reaction occurs, so that slower and more uniform hardening takes place thereby eliminating the tendency to crack in combination with bonding resin adhesion. Example IV The ALTEK 52-563 resin was applied to a concrete wall surface with MEKP as the initiator and allowed to cure until the surface was tacky. The blend of E-704, ALTEK 52-563 and kaolin with MEKP initiator was then applied to the tacky surface. The resulting two layer coating could not be removed manually without destroying the coating or removing portions of the surface.

Example V Samples of solid cylinders of concrete were prepared by pouring a concrete mix of cement, sand, aggregate, and water into hollow plastic cylinder of 3" diameters with a 4" long, 1/4" diameter bolt positioned in the longitudinal axis position so that a portion of the bolt extended longitudinally outward beyond one concrete circular face. When the concrete had hardened, the plastic cylinders were removed and the circular end surfaces of a pair of cylinders opposite the bolt were coated with ALTEK 52- 563 resin containing an initiator. Each of the so coated cylinders was then inserted into opposite ends of a 3" plastic cylinder with the coated surfaces towards each other. The cylinders were inserted until the coated surfaces were about 1/4" apart and were held there. At this point, a hole was drilled into the plastic cylinder and the 1/4" space was filled with the liner resin mix or with the bonding/primer coating composition and allowed to harden. Details of the samples and the results are as follows:

Sample Make-Up Samples 1 through 3 were concrete cylinders 3" diameter bonded together with a bonding primer coat and a resin liner material Bonding/Primer Coat = Alpha/Owens-Corning ALTEK 52-563 Benzoyl Peroxide

Resin Liner = 12% ALTEK 52-563 28% Alpha/Owens-Corning E-704

60% Aluminum Silicate Kaolin

1% by Volume Methyl Ethyl Ketone was added to above mixture

Sample No. 4 comprised concrete cylinders of 3" diameters bonded together with a bonding/primer coat only.

Bonding/Primer Coat = Alpha/Owens-Corning

ALTEK 52-563 Benzoyl Peroxide (Initiator)

Sample No. 5 comprised 4000 psi concrete cylinders of 3" diameters bonded together with a bonding/primer coat only.

Bonding/Primer Coat = Alpha/Owens-Corning ALTEK 52-563 Benzoyl Peroxide (Initiator)

In the test, after the resins had cured and hardened, the opposed bolts of the cylinder pairs which were bonded at their coated surfaces were gripped and were pulled apart according to the procedures of ASTM-D638, "Standard Test Method for Properties of Un-Reinforced/ Reinforced Plastics" for determining tensile strength. The results were: TEST RESULTS

Sample No. Load (lbs) Bond Strength (PSΪT

1 1700 240

2 1650 233

3 2400 340

4 2300 325

5 2950 131

Samples 1 through 3 included the liner resin and the bond failures occurred with loads in the range of 500 lbs to 945 lbs. Samples 4 and 5 did not include the liner resin. Sample

4 shows the significant strength improvement which was discovered when using the benzoyl peroxide as an initiator.

Close inspection of the concrete surfaces coated with bonding/primer resin using benzoyl peroxide initiator revealed that the resin had penetrated the concrete up to 1/16" and more and had become an integral part of the concrete structural matrix. This degree of penetration across the concrete/resin interface provides a continuous, integral bonding resin layer that is locked into and is a part of the concrete surface structure. Although there is some penetration when MEKP is used as the initiator, the penetration is not to the same degree and depth.

Example VI

PREFERRED EMBODIMENT (TWO LAYER)

Hollow concrete cylinders were obtained to simulate the typical manhole, which, at its opening, is 24 inches. Usually, a manhole will increase in diameter below the surface going to 36 inches and then 48 inches. In the United States the average manhole depth is about 9 feet. Lifting stations, on the other hand, may run as deep as 30 feet.

The interior surfaces of the cylinders were first coated with the bonding/primer coating of sample 4 of Example V by spraying with a Venus Gussmer sprayer. After the surface cured and became tacky the resin liner mix of samples 1 through 3 of Example V was sprayed on the tacky surface of the bonding resin. After curing and hardening by using hammers with chisels and screw drivers the layers of resin could be removed from the concrete surface only by removing the concrete to which the resin was bonded. This lined substrate structure comprises two layers, a bond and a liner or finish layer.

Example VII PREFERRED EMBODIMENT (THREE LAYER)

A manhole lift station wetwell was rehabilitated by pressure washing to remove all debris, and to uncover the firm underlying surface. Then, a bonding coat of ALTEK 52-563 was applied as before. It has been found that in this application this layer should usually be 4 mils to be satisfactory and may preferably be as thick as 12 mils. Benzoyl peroxide was used as the initiator.

Reference will now be made to Figure 5 and 6 for this three layer embodiment. The manhole station 34 has the general configuration shown in Figure 6 where the manhole extends below ground lever 35 and has opening 41. In Figure 6, gun 20 is shown carried by control rod 38 which is held by one end of support line 39 which is threaded through block and tackle 37 which is swivally mounted and carried by tripod 36. Support line 39 at its other end is attached to counterbalance weight 40. The control rod 38 is provided with guide handle 42 so that the gun 20 can be rotated manually by an operator and can be raised and lowered aided by the stabilizing effect of the counterweight. Application preferably begins at the bottom and the operator rotates and raises the gun as each course is applied. A white pigment, Ti0₂, is used in mix 43 so that the operator can readily track the application of the mix. In another embodiment, tripod

36 can be replaced by a boom suspended from the rear of a service truck.

The application of the "structural" or "core" layer mix 43 is illustrated in Figure 6 and it comprises the orthophthalic polymer, 52-563, and the E704 isothalic resin mixed with milled fiberglass as the strengthening filler and with fumed silica to add thoxotropic properties. The preferred composition for highly acidic environments is about 30% 52-563 with about 70% E704 by volume and mixing this polymer blend with 30% to 80% by volume of milled fiberglass, about 2% to 4% benzoyl peroxide and about 1.5% fumed silica. The ratio of the polymer blend to the fiberglass will depend on ambient temperature and humidity and is adjusted accordingly. In environments which are less acidic preferred core layer composition is about 20% to 22% orthophthalic polymer resin, 48% to 50% ground fiberglass, 23% to 25% kaolin clay, 2% to 4% initiator of benzoyl peroxide, and about 3% fumed silica.

This core layer is applied at a minimum thickness of 1/4" and, depending on the condition of the lift station surface, may be up to 4 " .

The gun 20 which applies the core mix or composite is schematically represented in cross-section in Figure 5. Gun 20 comprises barrel 21 which is closed at one end, static mixer 22, delivery tube 23, atomizer 24, and nozzle 25. In the preferred design the barrel has a 3/4" diameter; the delivery tube, 1/4"; and the nozzle, 1/8". Ball valve 28 controls the acetone supply line 31 and the acetone is used to flush the gun before each operation begins. In operation, the composite is supplied by line 32 and controlled by ball valve 29. The composite is the mix 43 before the initiator is injected through valve 28 supplied by line 31.

The ability to apply by spraying a highly filled polymer is an especially important feature of the invention. To enhance the spraying quality, the compressed air is injected into the composite stream at an oblique angle. This is preferably done in atomizer 24 where the air enters at a preferred angle of 45°. This is angle 35 in Figure 5.

The initiator and composite are mixed in static mixer 22 to become mix 43. Static mixers such as the Cleveland Static Mixing System can be obtained from EMI of Bedford, New Hampshire, USA and are preferred.

The mix 43 is now pumped through tube 23 and is atomized by the injection of compressed air, preferably at about 185 ft³/min at about a 45° angle as mentioned above to the direction of flow and inclined into the line of flow to dispense and atomize the mix. The atomized mix exits through nozzle 25 to be applied to the manhole wall. All the containers, pumps to deliver the aforementioned ingredients, lines, valves, barrel atomizers, and nozzle are equipment and materials readily understood and obtainable by those skilled in the art once they have read this description. In this specific embodiment a Venus Gusmer 22-1 Airless Piston Pumps are used with the above described spray gun 20.

The structural or core layer is especially useful on badly deteriorated surfaces and uneven surfaces. The strength of the structural composite core material is about 18,000 psi or about four times that of concrete. The thickness applied is generally dependent on the ratio, that is, 1/4" of core layer has the equivalent strength of about 1" of concrete.

The finish layer, or liner layer, is the liner layer from Example VI above and is applied to a minimum thickness of 20 mils and may be up to 1/4".

This three layer composition comprises the bond or coating layer, the core or structural layer, and the finish or liner layer, and provides an exceptionally strong and acid resistant lining that rehabilitates deteriorated lift stations and manholes .

Example VIII In repairing and rehabilitating a manhole with a defined leak, the following steps were performed. The walls were first pressure washed to remove all debris and deteriorated concrete .

Major leaks with washout cavities were located and plugged with either a foam injection system as manufactured by Prime Resins, Atlanta Georgia or Hydraulic Cement Water Plug or with other suitable plug materials. Then, the wall was sprayed and hand brushed/rolled as necessary with 52-563 bond coat resin with Ti0₂ white color pigment and benzoyl peroxide initiator. The applied coating was cured in about 30 to 45 minutes whereupon it was in a hardened condition.

The application of the patch will now be described. Additional weep holes were now apparent on the white bond coat surface after curing. Using a paint brush, generous coats of finish liner material, described hereinabove, with benzoyl peroxide 2% to 4%, was applied approximately 6" around each leak that was discovered. Higher initiator concentration may be used for quicker set up time on the polymers applied to the patch. A semi -porous polymer reinforced fabric was next applied to the coated area, and then another generous coat was applied to finish the patch. Other features could be used such as burlap but more strength is available in polymeric reinforced fabric. The adhesion of the finish liner composite coupled with the polymer reinforced patch holds water long enough for resins to gel and cure .

If the wall structure surface has badly deteriorated, the fiberglass filled structural or core liner material will be used to bring the structure back to its original integrity. Structural liner should be applied at 1/4" thickness per 1" of deteriorated concrete wall. If the structural integrity of the wall is not in question, the fiberglass filled structural liner will not be used in order to reduce costs.

The finish liner was next added. Approximately 1/4" of material was spray applied.

In areas with high concentrations of hydrogen sulfide or, as an additional guard against pinholes, an additional coat of low viscosity finish liner can be added in the thickness range of 6 to 8 mils.

Example IX

Steel plate sections were coated according to the process of the invention as described in the foregoing Examples by first applying the bonding resin and then the liner resin.

As with the concrete sampler above, delamination could not be initiated with hand tools.

Because of the strong bond to steel that can be achieved, the coating and method of the invention provides an excellent protective lining for steel in storage and naval vessels, piping, beams and plate exposed to corrosive environments. The invention has the advantage that the surfaces to be coated can be selected and coated before or after construction is completed. The present invention provides a method by which highly filled polymeric resins can be pumped and applied to be surfaces to be coated by spraying. The filler not only increases the strength of the coating, it significantly decreases the tendency to crack by dispersing heat. A mixture from 50% by volume to 80% by volume of filler can be successfully applied.

Although certain specific embodiments and a preferred embodiment of the present invention have been shown and described above, it is to be understood that many modifications thereof are possible and may occur to those skilled in the art after having read the foregoing specification. The invention, therefore, is not to be restricted except insofar as is necessary by the prior art and the spirit and intent of the scope of the following claims .

Claims

What is claimed is:

1. A composition for lining, protecting, restoring or finishing a substrate surface and for forming molded structures comprising, prior to cross-linking: a. a blend comprising a major portion of a thixotropic, isophthalic, unsaturated polyester resin, and a minor portion selected from the group consisting of non- thixotropic, unsaturated polyester resins and blends thereof with vinyl ester polymer resins, and orthophthalic polymer resins; b. a filler comprising a heat dispersant material, mixed with said blend, said filler comprising 30% to 70% by volume of the mixture; c . a catalyst ; and d. an initiator.

2. The composition of Claim 1 wherein the catalyst is selected from the group consisting of cobalt, compounds containing cobalt, dimethylaniline, and aniline catalysts.

3. The composition of claim 2 wherein the initiator is selected from the group consisting of benzoyl peroxide and methyl ethyl ketone peroxide.

4. The composition of claim 3 wherein the filler is selected from the group consisting of ground fiberglass, kaolin clay, and blends thereof.

5. The composition of claim 1 wherein said filler comprises an aggregate to provide a composition for a molded article .

6. A substrate surface structure wherein the surface is lined with a composition to preserve, protect, and/or restore said surface comprising: a. a substrate surface, said surface being composed of a material selected from the group consisting of concrete, masonry, steel, and sub-roofing; b. a coating layer bonded to said surface, said coating layer comprising a resin selected from the group consisting of non-thixotropic unsaturated polyester bonding resins and orthophthalic polyester resins; and, c. a liner layer directly bonded to said coating layer, said liner comprising: a blend of a resin, selected from the group consisting of the polyester resin of the coating layer and blends thereof with vinyl ester polymer resins with a thixotropic, isophthalic, unsaturated polyester resin; and, said blend of resins being blended with a heat dispersant fillers selected from the group consisting of ground fiberglass, kaolin clay, and blends thereof.

7. The structure of claim 6 wherein the substrate surface is a concrete wall surface and which includes a core layer interposed between said coating and liner layers being directly bonded to each of said layers on opposed surfaces, said core layer comprising an orthophthalic polyester resin, milled fiberglass filler and fumed silica.

8. The structure of claim 6 including a patch interposed between and coating and liner layers.

9. The structure of claim 6 wherein the substrate surface is steel.

10. The structure of claim 7 wherein the polymer of the core layer comprises a blend of about 70% thixotropic, isophthalic unsaturated polyester resin with about 30% of the orthophthalic polymer.

11. The structure of claim 7 wherein said core layer comprises about 25% to 23% kaolin clay, about 48% to 50% ground fiberglass, about 3% fumed silica, about 20% to about 22% orthophthalic polymer, and 2% to 4% benzoyl peroxide initiator.

12. A method for preserving, protecting, or restoring a substrate surface comprising the steps of: a. cleaning the surface to remove loose material; b. applying a coating resin to said surface to form a coating layer, said coating resin comprising a non-thixotropic unsaturated polyester resin, and, c. blending a resin selected from the group consisting of its non-thixotropic unsaturated polyester resins of the coating layer with a thixotropic, isophthalic unsaturated polyester resin, a catalyst and a heat dispersant filler to form an acid resistant resin mixture; d. combining an initiator to initiate curing of the polymers in said mixture; and, e. applying said combined mixture directly to said coating layer thereby providing a lined, protected surface.

13. The method of claim 12 wherein said substrate surface is new or deteriorated concrete, said method comprising the additional steps of: i) providing an initiator of benzoyl peroxide; ii) combining about 25% by volume of the coating resin with about 75% by volume of the acid resistant resin in a shear mixer to form a blend and then adding 30% to 70% by volume to the blend of a filler of ground fiberglass to form a liner resin mixture ; iii) pressure washing the concrete surface to be protected to remove loose surface particles and expose the underlying firm surface; rinsing; and leaving said surface damp; iv) applying said coating resin to said surface while damp in a thickness from about 5 mils to about 30 mils and allowing the surface to become tacky, v) adding up to 2% by volume of catalyst to the liner resin and subsequently combining therein about 1.5% by volume of the initiator thereby causing the resulting mixture to begin hardening, and, vi) applying said mixture to the tacky coating surface whereby as the mixture completes the hardening process an acid resistant liner is produced.

14. The method of claim 13 including the step of providing a sprayer and wherein in steps (iv) and (v) said liner resin and catalyst are fed into the sprayer and subsequently, said initiator is added to the liner resin within the sprayer as said mixture is applied by spraying.

15. The method of claim 12 wherein prior to step (e) a core layer is applied, said core layer comprising an orthophthalic polymer, a ground fiberglass filler, a fumed silica thixotropic agent, and an initiator, and, in step (e) said combined mixture is applied directly to the core layer.

16. The method of claim 15 wherein said core layer is applied by first combining said orthophthalic resin, filler, and thickening agent to form a composite, injecting said initiator into said composite and then passing the composite through a compressed air atomizer to atomize the composite, and then spraying the atomized composite onto said coating layer.

17. The lined structure of claim 9 wherein the steel substrate surface is selected from the group consisting of navel and storage vessels.

18. The lined substrate surface of claim 6 wherein the substrate surface is a roofing substructure.

19. A sprayer apparatus for applying the composite of the core layer of claim 8 and similar composites to substrate surfaces comprising: a) an elongated barrel of generally cylindrical shape, said barrel being closed at one end; b) a polymer composite supply line with control valve and pump means operably associated therewith for admitting composite into said barrel; c) an initiator supply line with control valve and pump means operably associated therewith for injecting initiator into said barrel downstream of said composite valve; d) a static mixer at the open end of the barrel to receive and complete mixing of the composite and initiator, said mixer being downstream of the initiator injection; e) a delivery tube of smaller diameter than said barrel attached at one end to the static mixer to receive said mixed and injected composite; f) an atomizer with compressed air supply means for injecting air into the composite stream as it is pumped through the atomizer; having an inlet and outlet means, said atomizer attached to the other end of said delivery tube at its inlet to receive injected composite through said tube; said air supply means being positioned to inject air into composite stream at an oblique angle to the direction of composite flow; and, g) a spray nozzle attached to the outlet means of the atomizer to spray the composite onto a surface.

20. The sprayer apparatus of claim 19 including suspension means for rotatably suspending said sprayer within a manhole for spraying a manhole wall surface.

21. In the method of spray coating a surface with a filed polymer, the improvement comprising: a) preparing a blend of a minor portion of polyester resin and a major portion of heat dispersant filler; b) combining said blend with an initiator to form a mixture; c) pumping said mixture through a nozzle while injecting compressed air into the mixture to produce a spray; d) applying said spray to a surface to provide a coated surface.

22. The method of claim 21 wherein the major portion of filler is in the range from about 50% to 80% by volume of said blend.

23. The method of claim 21 wherein the filler includes fumed silica and the filler material is selected from the group consisting of kaolin clay, ground fiberglass, and blends thereof.

24. The method of claim 21 wherein the polyester resin comprises a blend of at least 30% by volume of an isothalic polyester resin with the balances of the resin blend being an orthophthalic polyester resin.

25. The method of claim 21 wherein the compressed air is injected at an oblique angle to the direction of flow of the mixture .

26. The coated surface product produced by the method of claim 21.

27. A method of patching a masonry surface that has leaking cavities, cracks, or holes comprising the steps of: a) plugging the cavity with a plug material; b) applying a bond coating layer to the surface adjacent the cavity and allowing the coating layer to cure and become tacky; c) applying the liner coating of claim 1 to the tacky surface around the cavity; d) positioning a fabric patch over the plugged cavity and pressing it against said liner coating; and, e) applying an additional liner coating over the positioned fabric patch whereby upon curing a finished patch is provided .

28. The patch produced according to the process of claim 27.