MXPA99003955A - Microencapsulatable solvent adhesive composition and method for coupling conduits - Google Patents

Abstract

A microencapsulatable solvent adhesive composition for coupling plastic conduits, such as pipes, connectors and related fittings comprises a water-insoluble polymer and a mixture of volatile organic solvents for the polymer, each of the solvents having 6 to 40 carbon atoms. This solvent adhesive composition is suitable for microencapsulation by aqueous-based microencapsulation processes. A plurality of microcapsules encapsulating the solvent adhesive composition are bound to a polymeric surface of a conduit, such as a pipe connector or fitting, by a binder composition, to form a surface coated with a layer of rupturable microcapsules. When the microcapsules are ruptured upon joining of the coated conduit to a second conduit, the volume of the released solvent adhesive composition is sufficient to cement the surfaces together.

Description

COMPOSITION OF ADHESIVE AND ICROENCAPSULABLE SOLVENT AND METHOD FOR COUPLING DUCTS AND DESCRIPTION OF THE INVENTION This application is a continuation in part of the Serial of the United States No. 08 / 741,193, presented on 29 October 1996, which claims the benefit of the Request U.S. Provisional No. 60 / 009,295, filed December 8, 1995. Non-metallic conduit segments, such as pipes, junction tubes and connectors which are designed to be interfined, are commonly joined together by inserting an end of one on one end of the other and sealing the joint with an adhesive. For example, polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC) or acrylonitrile butadiene styrene (ABS) pipe segments can be joined with the corresponding connectors or related tiepipes and the connection sealed with an adhesive and solvent. The adhesives and solvents are typically liquid solvents containing a small amount of dissolved polymer resin which is the same polymer, or a chemically similar polymer, which comprises the objects to be bonded.

When such adhesive and solvent gets to get in touch with • the surfaces of the objects, the solvent partially dissolves and softens the outer layers of the matt surfaces. The resin in the solvent solution fills any holes or spaces between the two surfaces joining the partially dissolved surfaces and wrapping the polymer chains. When the solvent evaporates, the polymer solidifies and a mechanical bond is created between the surfaces, forming a "solder solder". Conventional adhesives and solvents for PVC, CPVC and ABS and other plastics are known in the art and are generally a mixture of solvents selected on the basis of their ability to dissolve low and / or high molecular weight resin and their different rates of evaporation. . An appropriate mixture of solvents will completely dissolve the resin in the adhesive and reduce the solution to the desired solids concentration and viscosity for application and handling ability. Some organic compounds in the adhesive and solvent may not be true solvents for the resin, but they also function as plasticizers, softening polymer or swelling surfaces, to provide lubrication to the fixing between the conduits, such as pipe joints, and mobility to achieve proper alignment. In the context of this invention, the term "solvent" is proposed to include both solvents and plasticizers for the polymer. Adhesives and solvents may contain other additives, such as • as a dye to make the adhesive more visible, and inert fillers and other compounds to increase the solids content and / or to control the viscosity.

Conventional adhesives and solvents may contain one or a mixture of several different organic solvents. For example, adhesives and solvents for PVC or CPVC may contain, in addition to the PVC or CPVC resin, the solvents tetrahydrofuran (THF) and cyclohexane or a mixture of THF, methyl ethyl ketone (MEC), cyclohexanone and acetone. Similarly, a solvent for ABS in adhesives and solvents is typically MEC. Other reported solvents used in adhesives and solvents for PVC, ABS or CPVC are ethyl acetate, dimethylformamide and N-methyl-2-pyrrolidone. Since these solvents have different evaporation ratios, the amount of each of the solvents in the mixture determines the available free time for working capacity, fixation and adjustment. The cure of solvent welding occurs when most of the applied solvents have evaporated and the solder joints are fused together. Preferably, healing takes place within a reasonable period of time without the use of heat, pressure, ultraviolet light or extraordinarily mechanical devices. There are several problems associated with the use of conventional adhesives and solvents. For example, adhesives and solvents are liquids and are usually applied in an open environment to plastic surfaces with a brush or other tool immediately prior to bonding. surfaces. This application can be time consuming and wasteful, just as the adhesive and solvent can spread along a surface area greater than what is actually desired or it can be submerged or spilled. In addition, a loss of solvents can occur by evaporation during application. The same solvents are flammable and many have a high volatile organic content (VOC), with resulting safety and environmental concerns. A method for solving the above problems, described by the present invention, is to provide the end user with a suitable conduit segment, such as a pipe segment, junction tube or connector, which is pre-coated with an adhesive and solvent microencapsulated in a dry form. The user then simply couples the supplied conduit segment to a segment of complementary interfitting conduit and, applying ordinarily mechanical force, breaks the microcapsules to release the adhesive and solvent and stick the segments together. In this way, the previous problems of unwanted disposal, expenses and safety and environmental issues are materially reduced. It has previously been suggested that an adhesive and solvent "conventional, such as those described above, can be microencapsulated and coated on a pipe surface." However, no description has been found of a adhesive and solvnete conventional that is microencapsuble. The microencapsulation of separate components of certain adhesive compounds has been reported. For example, sections of pipes, such as polyester glass fiber or epoxy glass fiber, can be joined by an adhesive composition formed by a polymerization reaction that occurs as soon as the pipes are joined. In this system, a polymerization activator may be encapsulated in a breakable microsphere and dispersed in a solution containing polymerizable monomers and a polymerization catalyst. The microspheres are broken either before or after the adhesive is applied to the pipe, releasing the activator to initiate the polymerization reaction. It is also known that common epoxy adhesives can be formed in a two-part system by separately microencapsulating the epoxy resin and the curing agent and breaking the microcapsules to mix the two components. Secondary solvents can be microencapsulated for use in cosmetic compositions and a mixture of these capsules introduced, for example, into a suitable cosmetic vehicle before breaking the capsules to mix the solvents. Each of the systems described above, however, involves the separate encapsulation of individual system components. In this way, there is a need for a microencapsible adhesive and solvent composition for ducts plastics, such as those made of PVC, CPVC, ABS or mixtures thereof, containing a polymer resin and a mixture of suitable solvents. Preferably, the solvents in the composition are aggressive in dissolving or softening the polymer in order to provide sufficient lubrication or facilitate the insertion of a segment of conduit into the coupling conduit segment, such as in the interference junction tube, as well as well as improving free time for work capacity and adjustment. There is an additional need for microcapsules containing a sufficient volume of an adhesive and solvent composition to increase lubrication and to bond the surfaces coupled together with a desired bond strength. The present invention solves the aforementioned problems by providing a microencapsible adhesive and solvent composition for joining pipes, tie pipes or plastic connectors. The adhesive and solvent composition of the invention is microencapsible by water-based microencapsulation processes, and comprises 3 to 20 parts by weight of a water insoluble polymer, and 80 to 97 parts by weight of a mixture of volatile organic solvents for the polymer, each of the solvents comprising 6 to 40 carbon atoms, the solvent mixture having a solubility in water of less than two percent. Preferably the solvents of the group consisting of hydrocarbons are selected aromatics, cyclic ethers, esters, lactones, linear ketones, branched ketones, cyclic ketones, alkyl-substituted cyclic ketones, and mixtures thereof. In order to be microencapsible, the mixture preferably has a solubility in water of less than one and a half percent. The adhesive and solvent composition may comprise, in addition to the first polymer, 3 to 20 parts by weight of a second water-insoluble polymer which may be a copolymer of the first polymer. The polymer in the adhesive and solvent composition can be any water insoluble polymer that is solulibized or plasticized by the solvents of the invention. In one embodiment of the invention, an adhesive and solvent composition for joining PVC or CPVC conduits comprises PVC or CPVC resin and a mixture of solvents selected from toluene, butyl butyrate, cyclohexanone, 2-octanone, 2-methyltetrahydropyran. A preferred adhesive and microencapsulable solvent of the invention for PVC or CPVC conduits comprises a mixture of 3 to 10 parts by weight of the PVC resin, 3 to 10 parts by weight of the PVC copolymer resin of vinyl acetate and PVC , 0 to 50 parts by weight of 2-octanone, 0 to 35 parts by weight of 3-methyltetrahydropyran, 20 to 60 'parts by weight of butyl butyrate and 20 to 60 parts by weight of toluene. In another embodiment, the adhesive and solvent of the invention for PVC or CPVC conduits comprises 4 to 20 parts by weight of PVC resin, 8 to 40 parts by weight of cyclohexanone and 40 to 88 parts by weight of toluene. The invention provides a plurality of microcapsules comprising an encapsulated volume of the adhesive and solvent composition of the invention. The microcapsules comprise an average diameter of 100 to 1000 μm, preferably 250 to 600 μm, and the weight of the encapsulated volume of the adhesive and solvent comprises 50 to 9Q percent, preferably 70 to 85 percent, especially 80 percent by weight of the microcapsules. In this way, the microcapsules provide a sufficient volume of the adhesive and solvent to increase the lubrication and bond the surfaces coupled together with a desired bond strength. The invention provides a cementitious composition suitable for joining the plurality of microcapsules to a polymeric wall surface, such as that of a pipe, coupling or coupling pipe. The cementing composition comprises the polymer of the wall surface, or a chemically related polymer, and a volatile organic compound that is solvent for the polymer. The alginate composition is not reactive with the walls of the microcapsule and does not remove the solvents from the adhesive and encapsulated solvent of the microcapsules. The invention also provides a polymeric wall surface at least partially coated with the plurality of microcapsules encapsulating the adhesive and solvent composition, bound to the surface by the cementing composition of the invention. In one embodiment of the invention, the polymeric wall surface coated with microcapsule comprises a segment of a conduit, such as a pipe, coupling or coupling tube. When the microcapsules are broken by coupling the treatment conduit with a wall segment surface of secondary interfitting conduit, such as in an interference junction tube, a sufficient volume of the adhesive and solvent is released by the plurality of microcapsules to bond the surfaces each. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of a method for coating a polymeric wall surface of a conduit, such as a pipe, connector or fixation, with a dispersion of a plurality of microcapsules comprising the adhesive and solvent of the composition in a cementing composition. Figure 2 is a schematic illustration of a method for coating a polymeric wall surface of a conduit, such as a pipe, connector or fixation with a cementitious composition, followed by the application of a plurality of microcapsules comprising the adhesive and solvent of the composition. Figure 3 is a cross-sectional view schematic of a wall segment of a polymeric conduit, such as a pipe, connector or fixation, the inner surface of which is coated with the microcapsules comprising the adhesive and solvent composition of the invention before coupling with a second conduit of interfijación. Figure 4 is a schematic cross-sectional view of the coated wall surface of the polymer tubing, connector or fixture of Figure 3 which engages with a second interface duct surface whereby the coupling force of the ducts each one breaks the microcapsules, releasing the adhesion and solvent composition. The present invention relates to a novel formulation for an adhesive and solvent composition that is microencapsible by known water-based microencapsulation processes. The adhesive and solvent composition comprises a water insoluble polymer and a mixture of volatile organic solvents for the polymer, and has a high solids content to provide improved lubrication. The adhesive and solvent composition can be used to bond together any type of plastic conduit including, but not limited to electrical, water, drainage, waste, vent and wastewater pipelines, and appropriate connectors and junction pipes therefor. The ducts can be manufactured of PVC, CPVC, ABS, polyacrylates, polystyrene, polycarbonates, or any homopolymer or copolymer soluble in an organic solvent comprising 6 to 40 carbon atoms, as described below. Preferably, the plastic conduits comprise PVC, CPVC, ABS or mixtures thereof, as these are widely used for conduits. Although it has been previously suggested that conventional adhesive and solvent compositions, such as those widely used for bonding PVC, CPVC and ABS pipes, can be microencapsulated, it has been discovered that these conventional solvent and adhesive mixtures are not encapsulated by either Known or aqueous organic microencapsulation processes known. It is therefore necessary to identify a combination of solvents and resins which can be microencapsulated and which have the properties, described above, which are necessary for effective coupling and bonding of the plastic conduit segments. In this way, the invention does not employ solvents commonly used in adhesives and solvents, such as THF, MEC, acetone, dimethylformamide, ethyl acetate, and N-methyl-2-pyrrolidone, as well as it has been discovered that they are not encapsulated by processes of known microencapsulation due to its dual solubility, that is, they are soluble, at various degrees, in both organic and water. In contrast, the mixture of volatile organic solvents in the adhesive and solvent composition of The present invention has a solubility in water of less than two percent, preferably less than one and a half percent, and is thus microencapsible by a process of microencapsulation with water. The solvents used in the solvent mixture of the composition of the invention are, in one aspect, selected for their ability to dissolve the resin in the adhesive and solvent and their ability to dissolve or be dissolved in the polymer surfaces to be joined. In this way, the more "aggressive" a solvent is, the more it is able to dissolve the polymer resin than the solvent and the faster the solvent is able to dissolve or soften (ie, plasticize) the surface layer of the polymer when Applies to a conduit. For example, 2-octanone, 3-methyltetrahydropyran and butyl butyrate are considered to be "aggressive" solvents for PVC and CPVC. As discussed below, each of these properties is important to provide lubrication for coupling and adjusting the surfaces of coupling conduits. Lubrication is increased by solids, such as polymer resin and inorganic fillers, such as fuming silica, in the adhesive and solvent mixture. The resins and / or fillers added improve the viscosity and provide a somewhat gelatinous texture to the adhesive and solvent. Therefore, in one aspect, for properties of Improved lubrication, it is preferable that the adhesive and solvent composition have a solids content as high as possible. In addition, the adhesive and solvent composition of the invention may contain other fillers and / or dyes, known in the art. A high resin content in the adhesive and solvent composition also allows the development of a strong polymer bond in solvent welding. Accordingly, the solvents of the adhesive and solvent composition are selected, in part, on the basis of their differential ability to dissolve high, medium or low molecular weight resins, or mixtures thereof. For example, toluene is an effective solvent for PVC resins, and CPVC of low molecular weight, but not high molecular weight; while butyl butyrate, cyclohexanone, 2-octanone and certain ethers, such as 2-, 3-, or 4-methyltetrahydrofuran, are effective solvents for both PVC and CPVC resins of high and low molecular weight. Preferably, in the solvent mixture, the proportion of solvents that "have the ability to dissolve resins of molecular weights, medium, and low to obtain maximum incorporation of resin dissolved in the adhesive to achieve a desired pull and bend resistance, is optimized. as discussed below, the solids content of the adhesive and solvent can be further increased by the addition to the mixture of a copolymer resin, as well as the copolymers random are generally soluble in solvents than homopolymers. The polymer resins dissolved in the solvent to form the adhesive and solvent composition of the invention can be freshly prepared polymer, or, in some cases, it can be a polymer that has been swirled. Generally, the polymer or polymers in the adhesive and solvent are identical or at least chemically similar to the surface of the polymer to be bonded. The solvents of the adhesive and solvent are selected, in another aspect, based on their differential evaporation ratio. As discussed above, the higher the evaporation ratio, the shorter the free time for work capacity; the lower the evaporation ratio, the greater the free time. One advantage of microencapsulating an adhesive and solvent composition is that the free time does not start until the microcapsules are broken by coupling together duct segments and the adhesive is released and solved. The adhesive and solvent composition of the invention is preferably dried to the touch in about 3-5 minutes and cured at ambient conditions within a reasonable period of time without the use of heat devices, session, ultraviolet light or extraordinarily mechanical. The process of It is well known in the technique and is not in itself part of the present invention. Typical microencapsulation techniques that can be used in the present invention are described in U.S. Patent 3,922,373; 4,073,946; 4,107,071; 4,377,621; and 4,536,524; the descriptions of which are incorporated herein by reference. Briefly, the adhesive and solvent composition of the present invention is hydrophobic, having a solubility in water of less than two percent, and thus can be microencapsulated by a process in which the adhesive and liquid solvent composition is dispersed in a stirred aqueous solution containing a dissolved crosslinkable polymeric material. The hydrophobic solvent composition forms a plurality of discrete liquid core core material entities in the aqueous solution. The size of the discrete capsule core material entities depends on the desired size of the end use microcapsules and is controllable by varying process conditions, such as temperature, viscosity of the core material, and the intensity of agitation in the system. . A material that induces phase separation, which is also soluble in the aqueous solution, decreases the affinity of the polymeric base material for water and increases its affinity for the core material in a hydrophobic capsule. In this way, the polymeric base material is induced to leave the aqueous phase and form a film around the core material in hydrophobic capsule. The polymeric film is subsequently crosslinked by known crosslinking agents to form a capsule wall around the core material. The aqueous solvent trapped in excess is then extracted from the resulting microcapsules, which are subsequently dried and ready for use. Suitable reagents, solvents and process conditions for performing the microencapsulation of the adhesive and solvent composition of the present invention are known in the art. Suitable crosslinkable polymeric base materials that form the microcapsule wall encapsulating the adhesive and solvent composition of the invention include, but are not limited to, one or more of the following: aminoplastics, gelatin, ethylcellulose, formaldehyde, glutaraldehyde, gum Arabica, melamine, polyvinyl alcohol, resorcinol and urea. Suitable phase separation inducing materials for use with these crosslinkable polymeric base materials vary according to the material employed, and are known to those skilled in the art. The adhesive and solvent composition of the invention which is suitable for water-based microencapsulation, comprises: a) 3 to 20 parts by weight of a water-insoluble polymer; and (b) 80 to 97 parts by weight of a mixture of volatile organic solvents for the polymer of (a), each of solvents comprising 6 to 40 carbon atoms, the mixture of solvents having a solubility in water of less than two percent. The solvents are preferably selected from the group consisting of aromatic hydrocarbons, cyclic ethers, esters, lactones, linear ketones, branched ketones, cyclic ketones and alkyl-substituted cyclic ketones. In order to be microencapsible, the solvent mixture has a solubility in water of less than two percent, that is, it is not necessary that each of the individual solvents have a water solubility of less than two percent, but only that the mixture of solvents has this property. Preferably, the mixture has a solubility in water of less than one and a half percent. As a measure of volatility, each of the solvents in the mixture preferably has a boiling point that approaches or is greater than the boiling point of the water. Solvents with lower boiling points than water have high volatility and are generally small, lightweight molecules that evaporate very rapidly to be encapsulated and / or can not be retained by a normally porous polymeric capsule wall. The polymer in the adhesive and solvent composition can be any water-insoluble polymer that is solubilized or plasticized by the solvents of the invention, as described above, but is preferably selected from the group consisting of polyvinyl chloride, chlorinated polyvinyl chloride, acrylonitrile butadiene styrene ppolymer, and mixtures thereof that can be formed, for example , by coextrusion of the individual polymers. The polymer can include, but is not limited to, PVC and high molecular weight homopolymeric PVC, PVC and low molecular weight homopolymeric CPVC, and mixtures and copolymers thereof. In one embodiment of the invention, the adhesive and solvent composition comprises ABS resin having a minimum butadiene content of 6%, a minimum acrylonitrile content of 15% and a minimum styrene or substituted styrene content of 15%. Preferably, the Abs resin comprises 6-15% butadiene, 25-45% acrylonitrile and 40-60% styrene or substituted styrene. More preferably, ABS comprises 35-37% acrylonitrile, 7-10% butadiene and 53-58% styrene. As discussed above, in order to increase the solids content of the adhesive and solvent, 3 to 20 parts by weight of one or more additional water-insoluble polymers or water-insoluble copolymers of the polymer of (a) in the Adhesive and solvent composition. For example, one embodiment of the adhesive and solvent composition of the invention for PVC conduit may comprise 3 to 10 parts by weight of homopolymeric PVC resin and 3 to 10 parts by weight of a vinyl chloride copolymer resin. Vinyl chloride copolymers are known in the art and include, for example, copolymers of vinyl chloride with one or more copolymerizable monomers having at least one CH2 = C terminal group, such as other vinyl halides and vinylidene halides; esters of acrylic acid, such as methyl acrylate, ethyl acrylate, etc .; esters of methacrylic acid, nitriles, such as acrylonitrile, methacrylonitrile, etc., acrylamides, such as methyl acrylamide, etc .; vinyl ethers, such as ethyl vinyl ether, vinyl ketones; vinyl acetate; vinylpyridine, etc; The vinyl chloride copolymers can contain up to 50%, preferably up to 20% of the copolymerizable monomers. CPVC useful in the compositions of this invention includes chlorinated polyvinyl chloride homopolymers and copolymers. The CPVC resins useful in this invention can be prepared by chlorination of any of the polyvinyl chloride homopolymers or copolymers discussed above by methods known to those skilled in the art. Commercially available CPVC resins can contain 57% to about 75% by weight of chloride. In one embodiment of the invention, an adhesive and solvent composition suitable for microencapsulation and for gluing together PVC and / or CPVC conduits comprises PVC resin and / CPVC and a mixture of solvents selected from toluene, butyl burate, 2-methyltetrahydropyran, 3-methyltetrahydropyran, 4-methyltetrahydropyran, 2-octanone and cyclohexanone. A preferred microencapsulable adhesive and solvent of the invention for PVC and / or CPVC conduits comprises a mixture of 3 to 10 parts by weight of the PVC resin, 3 to 10 parts by weight of vinyl acetate copolymer resin and PVC, to 50 parts by weight of 2-octanone, 0 to 35 parts by weight of 3-methyltetrahydropyran, 20 to 60 parts by weight of butyl butyrate and 20 to 60 parts by weight of toluene. More preferably, the composition comprises 4 to 8 parts of PVC, 4 to 8 parts of vinyl acetate copolymer resin and PVC, 0 to 30 parts of 2-octanone, 0 to 32 parts of methyltetrahydropyran, 25 to 50 parts of butyrate. of butyl and 25 to 50 parts of toluene. Still more preferably, the composition comprises 5 parts by weight of PVC resin, 5 parts by weight of PVC vinyl acetate copolymer resin, 30 parts by weight of 3-methyl tetrahydropyran, 30 parts by weight of butyl butyrate and 30 parts by weight. toluene weight. In another embodiment, the adhesive and solvent composition of the invention for PVC and / or CPVC conduits comprises 4 to 20 parts by weight of PVC or CPVC resin, 8 to 40 parts by weight of cyclohexanone and 40 to 88 parts by weight. from toluene Preferably, the composition comprises 4 to 10 pallets by weight of PVC or CPVC resin, 8 to 30 parts by weight of cyclohexanone and 60 to 88 parts by weight of toluene. More preferably, the composition comprises about 5 parts by weight of PVC resin or CPVC, about 10 parts by weight of cyclohexanone, about 83 parts by weight of toluene. A plurality of microcapsules encapsulate a volume of the adhesive and solvent composition of the invention. Preferably, the plurality of microcapsules comprise an average diameter of 100 to 1000 μm, especially 250 to 600 μm, and the weight of the volume of the adhesive and encapsulated solvent comprises 50 to 90 percent, preferably 70 to 85 percent, and more preferably 80 percent of the weight of the microcapsules. The diameter and volume of the microcapsules are controllable by controlling the parameters of the microencapsulation process, as described above. The average diameter of the plurality of microcapsules is determined mechanically by differential screening, as is known in the art. The weight of the volume of the encapsulated composition is determined by extracting the volume of the composition from the microcapsules. The extraction is generally carried out by heating the microcapsules in a solvent that is not encapsulated, such as MEC, THF or acetone, for a period of time sufficient to perform the extraction, typically three. to four days or more. After extraction, the residue, consisting of the capsular walls, is dried and weighed. The difference between the weight of the microcapsules before extraction and the weight of the microcapsule walls after extraction is the calculated weight of the original volume of the adhesive and solvent composition. The plurality of microcapsules may comprise a heterogeneous mixture of non-reactive microcapsules, such as microcapsules that separately encapsulate solvents or mixtures of solvents and / or other compositions. For example, the mixture may include microcapsules encapsulating individual solvents of the invention, such as toluene and the , to provide additional lubrication. Additionally, the plurality of microcapsules can be mechanically mixed with an additional lubricant compound, such as fumed silica or powdered graphite, usually prior to application to a polymeric surface, as described below. A dye can be added to the microcapsule walls by known means, either during the encapsulation process, or when the microcapsules are applied to the polymeric surface. The plurality of microcapsules encapsulating the adhesive and solvent are applied to a defined area on the surface of the polymer wall, such as that of a conduit, coupling or coupling tube, by a cementitious composition which is preferably a liquid and it comprises the polymer resin and 50 to 95 parts by weight of a volatile organic compound that is a solvent for the polymer. The binder is preferably a composition that is not reactive with the walls of the microcapsule and, under the conditions of application, does not remove the encapsulated solvents from the microcapsules. Therefore, the binder can comprise any of the adhesive and solvent compositions of the present invention, alternatively or in combination with any conventional solvent and adhesive, even those containing solvents with dual solubility, such as THF, MEC, or acetone. The adhesive and solvent composition in the binder can also be diluted with any solvent that is not reactive with the microcapsules. For example, a cementitious composition suitable for bonding microcapsules to a PVC or CPVC surface is a 50:50 by weight blend of cyclohexanone and a conventional adhesive and solvent, such as Low Oxyte VOC Cement manufactured by Oatey Company, Cleveland, Ohio, which comprises 10-20% PVC resin, 60-70% THF, 1-5% acetone, 5-515% MEC, 1-10% cyclohexanone, 2-3% fumed silica, less of 1% dye and 5-15% filler. Such conventional adhesive and solvent may contain additives, such as fillers and dyes, if they are non-reactive with the microcapsules. The plurality of microcapsules can be applied to the surface of the wall by any suitable method which can ensure that a sufficient amount of the microcapsules are bound to the surface to provide a sufficient volume of adhesive and solvent to glue the coated surface with a second surface when the two surfaces are engaged. A binder, such as that described above, facilitates the attachment of the microcapsules by partially solubilizing the polymer from the surface of the wall. As illustrated in Figure 1, the microcapsules 1 comprising the adhesive and solvent composition can be dispersed in the cementing composition 5, forming a suspension. In this way, the microcapsules can be applied to the polymeric surface of the wall of a conduit 3 simultaneously with the binder 5; however, preferably as illustrated in Figure 2 the binder 5 is applied, to plasticize the surface of the polymer wall of the duct 3 and make it sticky, and the microcapsules 1 are then applied to the surface, by spraying or other means. The curing of the adhesive and solvent of the binder provides firm adhesion of the microcapsules to the polymer to form a surface layer of breakable microcapsules. In this way, the method of the invention includes a method for applying microcapsules to a polymer wall surface, comprising the steps of: (a) providing a plurality of microcapsules encapsulating a volume of an adhesive and solvent comprising 3 to 20 parts by weight of a water insoluble polymer and 80 to 97 parts by weight of a mixture of volatile organic solvents for the polymer, each of the solvents that comprises 6 to 40 carbon atoms, the mixture of solvents having a solubility in water of less than two percent; (b) providing a polymeric wall surface comprising the water insoluble polymer of (a); (c) coating a portion of the wall surface with a cementitious composition comprising the water insoluble polymer of (a) and 50 to 95 parts by weight of a volatile organic compound that is solvent for the polymer; and (d) applying the plurality of microcapsules to the portion of the wall surface. The plurality of the microcapsules can first be dispersed in the cementing composition and the coating of the wall surface and the application of the plurality of microcapsules in one step can be realized. Preferably, the method further comprises the step of curing the cementing composition, wherein the plurality of microcapsules form a surface layer on the surface of the wall. Prior to the application of the binder and microcapsules to a first surface, or last coupling of a first coated surface to a second uncoated surface, one or both surfaces can be corrugated, for example, with the use of sandpaper, to provide a larger surface area for the microcapsule coating or the volume of the adhesive and solvent to adhere to, and increase the bond strength of the adhesive. Preferably, however, the corrugation of the surfaces is not performed. The total intention is to provide an adhesive and solvent which will bond two substrates through adhesion and not simple mechanical interference. When a dispersion of microcapsules is employed in the binder (Figure 1), preferably the dispersion is of a consistency which, when applied to the surface of the wall, there is a minimum of loss due to soaking or running. Preferably, such dispersion is painted or controllably spread on a defined portion of the surface. The proportion of the microcapsules and solvents in a dispersion depends, in part, on the desired thickness and / or weight of the coating on the surface, the binder used, and the nature of the surfaces to be bonded. In one embodiment of the invention, where the dispersion is applied to a PVC pipe surface, the dispersion comprises a plurality of microcapsules, a PVC cement of low VOC content, and a suitable solvent in a 2: 1 ratio: 1 in weight. The microcapsules can be applied to any surface of plastic conduit, but the coating of the The microcapsule is particularly useful when joining inter-connecting wall segments, pipe connectors or plastic related connecting tubes, such as in an interference junction tube. The microcapsules can be applied to a defined area on only one or both of the coupling surfaces, but preferably it is applied to a coupling surface only, such as the inner surface of a hood pipe segment (for pipes having bell ends and of opposite faucets). As illustrated in Figure 3, when applied to a connector or connecting tube 10, the microcapsules 12 are shown as pre-coated on the inner surface 14, rather than the outer surface 20, of one or both ends 16, 18 of the connector or connecting tube 10 for the last connection with the external surface of a pipe or other conduit 22. It is allowed to cure the agglutinate / microcapsule mixture, resulting in the evaporation of the agglutinate solvents and leaving a dry surface layer of the microcapsules firmly adhered to the polymer of the wall segment. The thickness of the microcapsule layer on the wall surface of the conduit is sufficient to provide a sufficient volume of adhesive and encapsulated solvent to result in a strong bond between the first and second coupling surfaces after rupture of the microcapsules and exposure from the surfaces to the adhesive and solvent. Generally, the microcapsules form at least one monolayer on the surface. In this way the thickness of the layer can be determined by the average diameter of the microcapsules. The dimensions of the surface area to be coated by the microcapsule layer are dependent on the relative internal or external diameter of the conduit, pipe, connector or connecting pipes to be joined. In general, the surface area to be coated comprises a band of a predetermined width around the inner or outer circumference of the conduit. The treated conduit (including the adhesive and microencapsulated solvent) can be packaged, transported or stored as such for up to the pre-determined half-life of the microencapsulated product. As illustrated in FIG. 4, when the wall segment of the microcapsule-coated polymeric conduit 20 is ultimately joined to an interlock coupling conduit segment 22, such as in an interference junction tube, the microcapsules 24 in the treated segment 20 is broken, releasing the volume of the adhesive and solved 26, and gluing the segments 20, 22 of the conduit, together, in the same way as conventional adhesives and solvents. The invention thus provides a polymeric wall segment of a conduit, coupling or fixing, the wall segment having a surface and a plurality of microcapsules attached to the surface to form a coated surface, the microcapsules encapsulating a volume of adhesive and solvent composition comprising 3 to 20 parts by weight of the polymer and 80 to 97 parts by weight of a mixture of volatile organic solvents for the polymer , each of the solvents comprising 6 to 40 carbon atoms. Preferably the solvent mixture has a solubility in water of less than two percent, more preferably less than one and one-half percent, and the solvents are selected from the group consisting of aromatic hydrocarbons, cyclic ethers, esters, lactones, linear ketones, branched ketones, cyclic ketones and cyclic ketones substituted with alkyl. Preferably, the polyvinylchloride polymer, chlorinated polyvinyl chloride, acrylonitrile butadiene styrene polymer and mixtures thereof are selected. A second conduit wall segment comprising the same polymer surface or is chemically similar as the treated conduit wall segment, and chemically reactive with the adhesive and solvent composition, is inter-fixed with the coated surface of the treated wall segment , such as in the interference junction tube, the second wall segment that engages the first wall segment with sufficient force to break the plurality of microcapsules on the coated surface and to substantially release the volume of the Adhesive and solvent composition, where the volume released is enough to glue the surfaces together. In this way, the method of the invention for gluing segments of inter-fixing of conduits, connectors or polymeric connecting tubes to each other, comprises the steps of: (a) providing a first polymer wall segment surface comprising a polymer selected from the group consisting of PVC, CPVC, ABS and mixtures thereof; (b) applying a cementitious composition to a portion of the first surface, the cementitious composition comprising the polymer of (a) and 50 to 95 parts by weight of a volatile organic liquid that is a solvent for the polymer; (c) applying a plurality of microcapsules to the portion of the first surface to form a coated surface, wherein the plurality of microcapsules encapsulate a volume of an adhesive and solvent composition comprising 3 to 20 parts by weight of an insoluble polymer in water and 80 to 97 parts by weight of a mixture of volatile organic solvents for the polymer of (a), each of the solvents comprising 6 to 40 carbon atoms, the solvent mixture having a solubility in water of less than two percent; (d) providing a second segment of polymeric wall having a surface comprising a polymer that is chemically reactive with the solvent and adhesive composition, the surface inter-fixing with the coated surface of the first segment of wall; (e) coupling the second wall segment to the first wall segment with sufficient force to break the plurality of microcapsules on the coated surface and substantially release the volume of the adhesive and solvent composition, wherein the volume released is sufficient to paste the surfaces between them; and (f) curing the adhesive and solvent composition to substantially bond the first and second conduit wall segments together. The utility of the adhesive and solvent compositions of the present is demonstrated by testing the bond strength of the polymer formed by solvent welding between the two coupling surfaces. For example, for the electrical conduit, the strength of the bond is measured by "pull resistance" or tensile strength, which is a measurement of the force required to separate two separate substrates which are bonded in adhesive form; and a "curve test", which is a test of the capacity of the link to resist the torque or curvature resistance. The integrity of the link is also tested by a "spill test" of liquid. For electrical piping, the standards for pull test, curl test and spill test are given by Standard 514B of Underwriters Laboratories (UL). For example, UL requires that a bond between connected PVC pipes of 12.7 mm (1 / inch) in diameter must be able to withstand a pull resistance of 67. 4 N (300 lbs), for one minute. Similarly, 19.05 mm (3/4 inch) diameter PVC joined pipes must withstand a pull strength of at least 101.2 N (450 lbs) for one minute. In the curving test, the links must support a gravity weight of 9.07 kg (20 pounds) for bonded pipes of 12.7 mm (1/2 inches) and 7.87 kg (35 pounds) for connected pipes of 19.05 mm (3/4 inches) ), with rotation through 360 ° C in one minute, without fracturing. The links must be demonstrated to be leak proof after immersion in or immersion in a liquid, such as water or kerosene, for a given period of time. For water pipes, the strength and integrity of the polymer bond must comply with applicable standards established by the American Society for Testing Materials. Typical adhesive and solvent compositions of the invention which are suitable for microencapsulation by water-based microencapsulation processes are illustrated by the following examples. Although the examples illustrate the adhesive and solvent compositions for PVC conduits, homopolymer resins and CPVC copolymer, described above, can be substituted in these examples by PVC homopolymer resins and PVC copolymer resins without departing from the scope of the invention. Example 1 Parts by weight Tolueno 45 Butyl butyrate 45 3 - . 3 - . 3-methyl tetrahydropyran 0 2-octanone or PVC resin 5 poly (vinyl acetate copolymer and vinyl chloride) content of 10% vinyl acetate Example 2 Parts by weight Tolueno 30 Butyl butyrate 30 3-methyl tetrahydropyran 30 2-octanone 0 PVC resin 5 poly (vinyl acetate copolymer and vinyl chloride) content of 10% vinyl acetate Example 3 Parts by weight Tolueno 45 Butyl butylate 0 3-methyltetrahydropyran 0 2-octanone 45 PVC resin 5 poly (vinyl acetate-vinyl chloride copolymer) content of 10% vinyl acetate Example 4 Parts by weight Toluene 29 Butylbutyrate 29 3 -methyltetrahydropyran 28 2-octanone 0 PVC resin 7 poly (vinyl acetate copolymer and 7 vinyl chloride) content of 10% vinyl acetate Example 5 Parts by weight Toluene 83.33 cyclohexanone 9.80 PVC resin 4.90 fumed silica 1.96 While the invention has been described herein with reference to the preferred embodiments, it is understood that it is not proposed to limit the invention to specific forms described. On the contrary, it is understood that it covers all the modifications and alternative forms that fall within the spirit and scope of the invention.

Claims (36)

1. CLAIMS 1. An adhesive and solvent composition suitable for microencapsulation, characterized in that it comprises: (a) 3 to 20 parts by weight of a water-insoluble polymer; and (b) 80 to 97 parts by weight of a mixture of volatile organic solvents for the polymer of (a), each of the solvents comprising 6 to 40 carbon atoms, the mixture of solvents having a solubility in water of less than two percent. The adhesive and solvent composition according to claim 1, characterized in that the solvents are selected from the group consisting of aromatic hydrocarbons, cyclic ethers, esters, lactones, linear ketones, branched ketones, cyclic ketones and alkyl substituted cyclic ketones. . The adhesive and solvent composition according to claim 1 or 2, characterized in that the polymer is selected from the group consisting of polyvinyl chloride, chlorinated polyvinyl chloride, acrylonitrile butadiene styrene, and mixtures thereof. 4. The adhesive and solvent composition according to any of claims 1 to 3, characterized in that it further comprises 3 to 20 parts by weight of a second polymer insoluble in water. 5. The adhesive and solvent composition according to claim 4, characterized in that the second polymer is a copolymer of the polymer of (a). The adhesive and solvent composition according to any of claims 1 to 5, characterized in that the polymer is selected from the group consisting of polyvinyl chloride, chlorinated polyvinyl chloride and mixtures thereof, and the solvents are selected from toluene, 2-octanone, 2-methyltetrahydrofuran, 3-methyltetrahydropyran, 4-methyltetrahydropyran, butyl butyrate and cyclohexanone. 7. A plurality of microcapsules characterized in that it comprises an encapsulated volume of the adhesive and solvent composition according to any of claims 1 to 6. 8. The plurality of microcapsules according to claim 7, characterized in that the plurality comprises a diameter average of 100 to 1000 μm. 9. The plurality of microcapsules according to claim 8, characterized in that the plurality comprises an average diameter of 250 to 600 μm. 10. the plurality of microcapsules according to any of claims 7 to 9, characterized in that the weight of the encapsulated volume of the composition of adhesive and solvent comprises 50 to 90 weight percent of the weight of the microcapsules. 11. The plurality of microcapsules according to claim 10, characterized in that the weight of the encapsulated volume of the adhesive and solvent composition comprises 70 to 85 weight percent of the microcapsules. 12. The plurality of microcapsules according to claim 11, characterized in that the weight of the encapsulated volume of the adhesive and solvent comprises 82 weight percent of the microcapsules. 13. A polymeric wall surface, the surface characterized in that it is at least partially coated with the plurality of microcapsules according to claim 7. 14. The polymeric wall surface according to claim 13, characterized in that the polymer of the The wall surface is selected from the group consisting of polyvinyl chloride, chlorinated polyvinyl chloride, acrylonitrile butadiene styrene, and mixtures thereof. 15. The polymeric wall surface according to claim 13 and / or 14, characterized in that the polymeric wall surface comprises a segment of a pipe, coupling or fixing. 16. The polymeric wall surface of according to any of claims 13 to 15, characterized in that the microcapsules are bonded to the surface by a cementitious composition comprising the polymer of the wall surface and a volatile organic compound which is a solvent for the polymer and is unreactive with the microcapsules. 17. An adhesive and solvent composition suitable for microencapsulation, characterized in that it comprises: (a) 3 to 20 parts by weight of a water-insoluble polymer selected from polyvinyl chloride, chlorinated polyvinyl chloride, and mixtures thereof; and (b) 80 to 97 parts by weight of a mixture of volatile organic solvents for the polymer of (a), wherein each of the solvents comprises 6 to 40 carbon atoms and is selected from the group consisting of aromatic hydrocarbons, cyclic ethers, esters, lactones, linear ketones, branched ketones, cyclic ketones, alkyl-substituted cyclic ketones, the mixture of solvents having a solubility in water of less than two percent. 18. The adhesive and solvent composition according to claim 17 characterized in that it further comprises 3 to 20 parts by weight of a copolymer of the polymer of (a). 19. The adhesive and solvent composition of according to claim 17 and / or 18, characterized in that the composition comprises 3 to 10 parts by weight of polyvinyl chloride resin, 3 to 10 parts by weight of copolymer resin of vinyl acetate and polyvinyl chloride, 0 to 50 parts by weight of 2-octanone, 0 to 35 parts by weight of 3-methyltetrahydropyran, 20 to 60 parts by weight of butyl butyrate and 20 to 60 parts by weight of toluene. The adhesive and solvent composition according to claim 19, characterized in that the composition comprises 4 to 8 parts by weight of polyvinyl chloride resin, 4 to 8 parts by weight of vinyl acetate-chloride copolymer resin. polyvinyl, 0 to 30 parts by weight of 2-octanone, 0 to 32 parts by weight of 3-methyltetrahydropyran, 25 to 50 parts by weight of butyl butyrate and 25 to 50 parts by weight of toluene. 21. The adhesive and solvent composition according to claim 20, characterized in that the composition comprises 5 parts by weight of polyvinyl chloride resin, 5 parts by weight of vinyl acetate copolymer resin and polyvinyl chloride, 30 parts. by weight of 3-methyltetrahydropyran, 30 parts by weight of butyl butyrate and 30 parts by weight of toluene. 22. The adhesive and solvent composition according to any of claims 17 to 21, characterized in that the composition comprises 4 to 20 parts in weight of polyvinyl chloride resin, 8 to 40 parts by weight of cyclohexanone and 40 to 88 parts by weight of toluene. The adhesive and solvent composition according to claim 22, characterized in that the composition comprises 4 to 10 parts by weight of polyvinyl chloride resin, 8 to 30 parts by weight of cyclohexanone and 60"to 88 parts by weight of toluene 24. The adhesive and solvent composition according to claim 23, characterized in that the composition comprises about 5 parts by weight of polyvinyl chloride resin, about 10 parts by weight of cyclohexanone and about 85 parts by weight of toluene. 25. A polymeric wall segment of a conduit, coupling or attachment, the segment having a surface coated with a plurality of microcapsules encapsulating a volume of an adhesive and solvent composition, the segment characterized in that it comprises: A first segment surface polymer, where the polymer is selected from the group consisting of polyvinyl chloride, polyvinyl chloride chlorinated, acrylonitrile butadiene styrene polymer, and mixtures thereof; and A plurality of microcapsules attached to a portion of the surface to form a coated surface, the microcapsules encapsulating a volume of a composition of adhesive and solvent comprising 3 to 20 parts by weight of the polymer and 80 to 97 parts by weight of a mixture of volatile solvents for the polymer, each of the solvents comprising 6 to 40 carbon atoms. 26. The polymer wall segment according to claim 25, characterized in that the plurality of microcapsules comprise an average diameter of 100 to 100 Q μ. 27. The polymer wall segment according to claim 26, characterized in that the plurality of microcapsules comprise an average diameter of 250 to 600 μm. 28. The polymer wall segment according to any of claims 25 to 27, wherein the weight of the adhesive and encapsulated solvent comprises 50 to 90 weight percent of the weight of the microcapsules. 29. The wall segment polymer according to claim 28, wherein the volume weight of the adhesive and encapsulated solvent comprises 70 to 85 weight percent of the microcapsules. 30. The wall segment polymer according to claim 29, wherein the volume weight of the adhesive and encapsulated solvent comprising 80 percent by weight of the microcapsules. 31. The polymer wall segment according to any of claims 25 to 30, characterized in that it further comprises a second wall segment of the duct, coupling or fixation, the second segment comprising a polymer that is chemically reactive with the adhesive and solvent composition and having a second wall segment surface inter-merging with the coated surface of the first wall segment, the second segment of wall that engages the first wall segment with sufficient force to break the plurality of microcapsules on the coated surface and substantially release the volume of the adhesive and solvent composition, wherein the volume released is sufficient to bond the surfaces together. 32. A method for applying microcapsules to a polymeric wall surface, characterized in that it comprises the steps of: (a) providing a plurality of microcapsules encapsulating a volume of an adhesive and solvent comprising 3 to 20 parts by weight of an insoluble polymer in water and 80 to 97 parts by weight of a mixture of volatile organic solvents for the polymer, each of the solvents comprising 6 to 40 carbon atoms, the solvent mixture having a solubility in water of less than two percent; (b) provide a polymeric wall surface comprising the water insoluble polymer of (to); (c) coating a portion of the wall surface with a cementitious composition comprising the water insoluble polymer of (a) and 50 to 95 parts by weight of a volatile organic compound that is solvent for the polymer; and (d) applying the plurality of microcapsules to the portion of the wall surface. 33. The method according to claim 32, characterized in that before step (c) the plurality of microcapsules are dispersed in the cementitious composition and the coating of the wall surface and the application of the plurality of microcapsules is carried out. in one stage. 34. The method according to claim 32 and / or 33, characterized in that it further comprises the step of curing the cementing composition, wherein the plurality of microcapsules form a surface layer on the surface of the wall. 35. A method for bonding segments of inter-fixing of conduits, connectors or polymeric union tubes to each other, characterized in that it comprises the steps of: (a) providing a first polymer wall segment surface comprising a polymer selected from the group consisting of of polyvinyl chloride, polyvinyl chloride chlorinated, acrylonitrile butadiene styrene polymer, and mixtures thereof; (b) applying a cementitious composition to a portion of the first surface, wherein the cementing composition comprises the polymer of (a) and 50 to 95 parts by weight of a volatile organic liquid that is a solvent for the polymer; (c) applying a plurality of microcapsules to the portion of the first surface to form a coated surface, wherein the plurality of microcapsules encapsulate a volume of an adhesive and solvent composition comprising 3 to 20 parts by weight of an insoluble polymer in water and 80 to 97 parts by weight of a mixture of volatile organic solvents for the polymer, each of the solvents comprising 6 to 40 carbon atoms, the solvent mixture having a solubility in water of less than two percent; (d) providing a second segment of polymeric wall having a surface comprising a polymer that is chemically reactive with the solvent and adhesive composition, the inter-surface fixation with the Coated surface of the first wall segment; (e) coupling the second wall segment to the first wall segment with sufficient force to break the plurality of microcapsules on the coated surface and substantially release the volume of the adhesive and solvent composition, wherein the volume released is sufficient to paste the surfaces between them; and (f) curing the adhesive and solvent composition to substantially bond the first and second conduit wall segments together. 36. The method according to claim 35, characterized in that before step (b) the plurality of microcapsules are dispersed in the cementing composition and the application of the binder composition and the application of the plurality of microcapsules is carried out in one stage