MXPA02001111A

MXPA02001111A - Uv-curable superabsorbent coatings.

Info

Publication number: MXPA02001111A
Application number: MXPA02001111A
Authority: MX
Inventors: Curtis Carter
Original assignee: Owens Corning Fiberglass Corp
Priority date: 2000-05-31
Filing date: 2001-05-16
Publication date: 2002-08-20
Also published as: CN1380897A; EP1208172A1; CA2380131A1; BR0106676A; AU2001264644A1; JP2003535234A; NO20020435L; NO20020435D0; WO2001092433A1; KR20020026248A

Abstract

Articles coated with a water-resistant coating that absorbs water to provide the water-resistant effect, and desorbs water when the coating is dried, and a method of providing water resistance and corrosion resistance to articles prepared with such coatings. The coating is formed by applying a composition comprising a non- aqueous solution of a water-swellable polymer and a liquid UV-curable resin onto the surfaces of the article, and curing to form a coating comprising the superabsorbent polymer by exposing to an ultraviolet (UV) light source.

Description

UV CURABLE SURFACE-CURING SURFACES DESCRIPTION Background and field of the invention The present invention relates to a high strength superabsorbent coating capable of rapidly absorbing water, which is convenient for coating a variety of articles that require a water resistant surface, including, but not limited to, reinforced or molded products, as well as reinforcement materials used in the manufacture of such products. More specifically, the coating is formed of a non-aqueous composition comprising a water-swellable polymer powder and a UV-curable liquid resin. The coating composition may further include a viscosity modifying agent. The inventive concept also relates to articles coated with the superabsorbent coating composition, including reinforced and molded products and fibrous reinforcing materials; as well as the methods to apply such coatings. The coating of this invention demonstrates a high level of water absorption and provides excellent dispersion and coating ability when applied to a substrate. 1 '? 3? &4% Deterioration caused by invasion of moisture under the exposed surfaces of items used in outdoor environments is a known problem. This deterioration includes oxidative deterioration caused by the reaction of water with the surfaces of reinforcing fibers used in these articles, as well as water-induced corrosion. In marine environments, for example, the problems associated with water saturation are due in particular to the salinity of the environment. The presence of salt in such aqueous environments accelerates oxidative decomposition. In non-saline environments, for example in environments with high atmospheric humidity, water-resistant coatings are necessary to protect the structures and surfaces of the equipment from moisture-induced decomposition. Items affected by the deterioration described above include articles that have a surface exposed to high humidity or humidity. Examples of such articles include reinforced rods and cables, such as fiber optic cables or telecommunications cables. These telecommunication cables are often used in situations where they are buried or submerged in water for long periods. As such, protecting water damage is critical to the structural integrity of these cables and to the success of the intended functions.

SOS ***. ^ M them perform. For example, a telecommunications cable may include a center comprising a glass rod that acts as a hardening or reinforcing member. This rod contributes to the rigidity of the cable. When water penetrates it comes in contact with the center element of the cable, corrosion or chemical deterioration of the cable infrastructure can result. To combat the problems associated with this water saturation damage, several strategies have been invented in an effort to provide water resistance to cables and other reinforced articles and to protect their sensitive internal surfaces from contact with water or water vapor present in the environment. surrounding. These techniques for making water repellent articles have included wrapping the articles in a protective coating material; or seal the surface to be protected. Sealing techniques can include chemically manipulating the surface layer of the article to make it resistant to water absorption, or applying a repellent coating. The technique of covering the surface with a protective coating material is conventional. It includes, for example, using a wrap or tape made of an impenetrable polymer with the ability to block water, or treating the wrapper material with an emulsion or solution of a water blocking polymer. The process for wrapping by coating does not require application of a compound or chemical treatment to the surface of the article; rather, protection is only derived from the coverage by the material to be coated. The coatings used to reject water have traditionally been composed of substances that are insoluble and impenetrable to water and therefore present a physical barrier to seize moisture. Such barrier coatings have included materials such as fats or gels. In the case of cables, for example, these coatings are applied by extrusion under pressure. There are, however, certain disadvantages associated with this type of coatings. Fats or gels are difficult to handle due to their slipperiness and contribute to an unpleasant perception of the coated article. This is an important factor to be considered in the manufacturing process, particularly because it affects the ease of cable handling during splicing operations. Fats and gels also undergo viscosity changes at low or high temperatures. These viscosity changes can affect the freeze / thaw performance and therefore the coating stability. The poor performance in this sense therefore affects the stable performance of the cables. More recently, non-greasy, dry, water-resistant coatings have been invented which, by themselves, have some degree of water absorption capacity. This ability to absorb water allows the coating to absorb moisture that makes contact with the article, while preventing direct contact with sensitive surfaces. The absorbent component in these dry water blocking coatings is a dry, granulated superabsorbent polymer that sponges and absorbs on contact with water. Superabsorbent polymers are typically characterized in terms of their foaming speed, foaming ability and gel strength. Traditional uses for these dry superabsorbent polymers have included items of personal hygiene products, food packaging articles and chemical spill cleaning compositions mainly, however recent experiments have included the use of these dry polymers to form coatings for other articles such as reinforced cables. For example, U.S. Patent 5,689,601 to Hager discloses a dry water blocking coating for reinforcing articles of reinforcing fiber using a dry water soluble or granulated water soluble blocking ingredient enclosed in one or more thin layers of a polymer for coat. This cover restricts the degree of water absorption that can be achieved by the granular polymer and consequently the swelling capacity of this layer is limited. Generally, either dry or fluid coatings are applied to fibers, ropes and reinforced articles such as cables that are made of these fibrous materials to the surface of the fibrous material and then cured before a subsequent process, if any. In general, the means for applying the coatings differ depending on whether a fluid coating is used or whether a solid particulate coating is being applied. In the case of dry coatings, the coating process using granulated water blocking agents involves some stages that consume time and labor that are directly related to the use of a granulated or powdered polymer. These steps include the need for one or more treatments with a binder resin and one or more spray resin applications in powder coating stations using an apparatus such as a fluidized bed. Alternatively, fluid coatings containing an absorbent polymer can be used.

* * - »- A disadvantage of aqueous coatings is the time required to fix and cure the coating after it is applied. Conventional coating processes that require heating, for example in stoves, or air drying, require additional process times. This produces higher process costs. Therefore there is a need in the medium for a water blocking coating composition for application to reinforced articles or reinforcing materials, which has a high water absorption capacity and a fast and concurrent swelling speed. Moreover, it is desired that such a coating be able to cure quickly and efficiently, without an expensive and time-consuming process. Surprisingly it has now been discovered that a highly absorbent water blocking coating having an excellent water-swelling capacity and a fast swelling rate can be formed from a non-aqueous coating composition comprising a non-aqueous UV curable liquid resin and a water-swellable polymer. Coatings containing this water-swellable polymer are capable of absorbing water substantially instantaneously when exposed to aqueous environments. ,5. fi In one aspect, this invention includes a method for providing water resistance to the surface of an article comprising: a) preparing a non-aqueous liquid coating composition comprising a water-swellable polymer; and a UV curable resin; b) applying the non-aqueous liquid coating composition to the surface of the article to form a coated surface; and c) exposing the coated surface to UV light and curing the non-aqueous liquid coating to form a water-resistant and water-absorbing coating layer comprising a water-swellable polymer on the surface of the article.

Detailed description of the preferred modalities The composition of this invention is convenient for forming a water-swellable coating on the surface of articles or materials that require surfaces that are resistant to water and therefore protects the material that is below the surfaces that are treated with the coating. The term "article", as used herein, is specifically intended to include any product or material having a surface that requires a water-resistant coating to protect the underlying structure from deterioration caused by exposure to moisture. Such articles include molded composite articles, laminates, sheets, fiber reinforcing materials known in the media and products made using one or more of these fiber materials, either collectively or in dispersed form within a matrix of any type. The term also includes articles made using reinforced fiber products, such as structural materials or equipment. As the water comes into contact with the coated surface of the article to be protected, the coating of the invention absorbs the water and sponges in volume. By absorbing the water, the coating effectively traps moisture and thus prevents it from coming into contact with the internal surfaces of the protected article. As a result, the sensitive internal surfaces remain dry and are protected from deterioration by water saturation. The coatings of this invention uniquely achieve water resistance protection by absorbing water to prevent penetration of moisture beneath the coating layer. The water-swellable polymer used in the coatings of this invention can be selected from any polymer capable of forming a non-aqueous solution for use in the coating mixture, and which, upon curing, has a swelling capacity and swelling speed that allows the absorption of water followed by desorption without loss of the polymer itself when the coating dries. Preferably, such polymer is in powdered form or in particulate form. The water-swellable polymer for use in the present invention can, for example, be selected from the group of polymers that possess the ability to absorb and desorb water amounts. Coatings comprising the highly absorbent water-swellable polymer of the present invention would absorb significantly higher amounts of water, demonstrating swelling ratios up to 75% dry weight or more. A desirable content of water-swellable polymer in the coating composition is in the range of 5-70% by weight. Preferably, the amount of the water-swellable polymer is from about 44% by weight to about 70% by weight based on the total weight of the composition. An example of a suitable water-swellable polymer is a polyacrylate powder commercially available under the tradename "AP80HS" from Emerging Technologies Inc.

The UV curable resin that is included in the coating composition of the present invention is suitably a non-aqueous liquid resin that is capable of curing rapidly and efficiently upon exposure to ultraviolet light. Such liquid and non-aqueous resin can be selected from UV-curable epoxides, polyethers, polyesters, polyurethanes, acrylates and combinations thereof. Preferably, the UV curable resin is a solvent free polyacrylate resin that is typically liquid at room temperature. Even though the resin must be a liquid, its viscosity, however, will vary as a function of temperature. Preferably, the UV curable resin is liquid at or above room temperature. An example of such a resin is a polyacrylate sold under the tradename "500 VINCH" by Zeon Technologies Inc. The UV curable resin can be included in the coating composition in a concentration of about 30% by weight to about 95% by weight, based on the total weight of the composition. Preferably, the UV curable resin concentration is from about 35% by weight to about 56% by weight. The compositions used to form the coatings of the present invention also comprise eleven Then, one or more photoinitiators, which initiate the crosslinking of the UV curable resin during the curing process. Examples of photoinitiators include "IRGACURE 651" or "IRGACURE 819" which are phenylketone photoinitiators commercially available from Ciba Specialty Chemicals. Depending on the commercial formulation of the UV curable resin that is selected, the photoinitiator can be included in the formulation. For example, the UV curable resin 500 VINCH is sold as a combined formulation containing a UV curable polyacrylate and one or more photoinitiators. The coating composition may also include one or more additives conventionally known for use in surface coating materials. For example, dyes, viscosity modifying agents, surfactants and lubricants can be added to the formulation. The amount of any additive can be easily selected according to the desired effect of the additive in the composition. The coating compositions can be formed by combining the water-swellable polymer powder with the UV curable liquid resin and the photoinitiator. Preferably, the ingredients can be combined at room temperature; however, the resin can be preheated before it is combined with the other ingredients. For example, the resin can be heated to 12 • * * - "&" a temperature ranging from room temperature to approximately 66 ° C (150 ° F) before mixing The mixture can be mixed by any convenient means In a preferred embodiment, a mixture of 50% by weight a water-swellable polymer powder, such as a polyacrylate powder, is combined with 50% of a UV curable liquid resin, such as acrylate resin.The coatings formed from this combination were found to provide the maximum swelling capacity of The coating composition of the invention can be applied to fibers, ropes, rods, cables and any other article that requires water blocking protection The coating composition can be applied to coat these articles by conventional means, including flooding, dipping , sprayed and any other known means.Where the items to be protected is a rope or reinforcing thread, the composition can be applied ecuadamente by means including, but not limited to, dive plunge-withdraw followed by passage through an extractor die. When the coating composition will be applied to a reinforcing cord or thread, the cord or thread may first be dressed with an appropriate sizing composition that is compatible with the ingredients in the composition. 13 . ^ tMa..m ^ te coating composition. The sizing step before applying the coating is preferred because it reduces the mechanical abrasion that can cause breakage of the fiber filaments in the cord or thread and agglomeration of the fluff in the process machinery. The water resistance properties of the coatings of the present invention are obtained by curing the non-aqueous composition, after it has been applied on the surface of the article, by exposure to ultraviolet (UV) light. Curing first by exposure to UV light allows rapid and efficient coating formation without the need for equipment such as furnaces that consume larger amounts of energy and which may require longer curing times. During the curing process, crosslinking occurs between the polymer chains, thereby allowing the coating containing the polymers to form a hardened layer that protects the underlying coated article by absorbing water as it contacts the coated surface. Suitably, at least one layer of the coating composition is applied to one or more surfaces of the article to form a coated surface. The coated surface is then exposed to UV radiation at a wavelength of about 200 to about 450 nanometers. The frequency of radiation is selected based on the curing requirements for the UV curable resin. For example, when 500 VINCH polyacrylate is used, a preferred frequency for curing the coating is approximately 350 nanometers. UV radiation can be provided by any convenient UV light source that provides radiation of the desired frequency. For example, a light box sold under the trademark "FUSION" can be used. When the coatings of the invention are applied to the reinforcing fiber cords surfaces and cured, they demonstrate a swelling capacity of about 75% the initial dry weight of the water-swellable polymer. Preferably, the swelling capacity for this type of application is from about 40% to about 60% by weight, based on the initial dry weight of the water-swellable polymer. Reinforced glass fiber articles comprising the water resistant coating described herein can be used in applications where exposure to water or water vapor is likely and where the formation of a durable, elastic and flexible coating with good waterproofing properties is desired. The following examples are representative of, but in no way limit the scope of this invention.

EXAMPLES Exemplary coating compositions were prepared by combining a water-swellable polyacrylate polymer powder, AP80HS and polyacrylate 500 VINCH, a non-aqueous UV curable liquid resin, in various proportions. The polymer powder and the UV curable resin were combined and mixed to form a homogeneous dispersion. The "ADVANTEX 25H" or "TYPE-E" glass cords, which are commercially available pre-subtracted glass yarns from Owens Corning, were passed through a bath containing the coating composition to impregnate the ropes. of impregnating them, the strings were passed through ur: given desired hole size extractor to continue the amount of composition of coating deposited on the surface of the rope, the reverse cord was then cured by exposure to UV light for a period of about 0.1 seconds to about 5 seconds as it passed through an array of UV ovens. ' The wavelength of ultraviolet light in UV ovens was approximately 365 nanometers Example 1 In this example, a UV curable coating composition was formulated by mixing a mixture of a superabsorbent polyacrylate and a UV acrylate in the proportions listed bottom: 95% by weight 500 VINCH UV acrylate made by Zeon Technologies, and 5% by weight AP 80HS provided by Emergin Technologies.

Example 2 In this coating composition, the same ingredients were combined as follows: 86% by weight of acrylate 500 VINCH UV; and 14% by weight of AP 80HS.

Example 3 An exemplary coating composition was developed according to the following formulation: 75.7% by weight of 500 VINCH UV acrylate; and 24.3% by weight of AP 80HS.

Example 4 In this example, a coating composition for UV curing was formulated by the following formulation: 64.9% by weight of 500 UV VINCH; and 35.1% by weight of AP 80HS.

Example 5 In this coating composition, the ingredients were combined as follows: 56% by weight of acrylate 500 VINCH UV; and 44% by weight of AP 80HS.

Example 6 In this coating composition, the ingredients were combined as follows: 45% by weight of acrylate 500 VINCH UV; and 45% by weight of AP 80HS.

Example 7 In this coating composition, the ingredients were combined as follows: 50% by weight of acrylate 500 VINCH UV; and 50% by weight of AP 80HS.

Example 8 In this coating composition, the ingredients were combined as follows: 30% by weight of acrylate 500 VINCH UV; and 70% by weight of AP 80HS.

Example 9 The coatings of Examples 1-8 were investigated to determine their swelling capacity in water when applied to reinforce fiber materials. The strings of ADVANTEX R25H and TYPE-E glass reinforcing fibers were coated with the coating composition of each of Examples 1-8. The glass was prepared with an aminosilane before the coating was applied. For each sample, the swelling capacity was measured, determined as the percentage of swelling over time calculated based on the total weight of the coating and fiber. The results obtained are included in Table 1: TABLE 1 a superabsorbent polyacrylate, Emerging Technologies Inc. b UV Acrylate, by Zeon Technologies Inc. c Fluff capacity measured as the percentage change in weight of the coated rope after 1 minute. The observed results indicate that a significant amount of water absorption could be achieved, for example where the proportions of either the superabsorbent polymer or the UV curable polymer is in a concentration of about 30% by weight to about 70% by weight, respectively . Having described and exemplified the invention, it should be noted that the following claims are not limiting but rather that the corresponding scope is given with the wording of each element of the claim and its equivalents. 20,, t x ^^ me & ú

Claims

CLAIMS 1. An article at least partially coated with a coating formed by curing a composition comprising a water-swellable polymer and a liquid UV curable resin by exposure to UV light. An article according to claim 1, characterized in that the coating absorbs water to provide a water resistant effect and desorbs water when the coating dries. An article according to claim 1, characterized in that the water-swellable polymer, after curing, absorbs up to about 75% of its dry weight in water when immersed in an aqueous environment. 4. An article according to claim 1, characterized in that the water-swellable polymer comprises a polyacrylate polymer. 5. An article according to claim 1, characterized in that the liquid UV curable resin comprises an acrylate resin. 6. An article according to claim 1, characterized in that it is a reinforced fiber material. twenty-one m ** ?? 7. An article according to claim 6, characterized in that it also comprises an aminosilane size under the coating. 8. An article according to claim 1, characterized in that it is a composite article. 9. An article according to claim 1, selected from the group consisting of ribbons, mats, fabrics, threads, fibrous strings, laminates, sheets, rods and cables. 10. An article according to claim 1, selected from the group consisting of molded articles, woven fabrics, cambric, wood and paper products and construction materials. 11. A suitable nonaqueous coating composition for forming a coating that absorbs and desorbs water, comprising a water-swellable polymer and a UV-curable liquid resin. 12. The non-aqueous coating composition according to claim 11, characterized in that the water-swellable polymer is a pulverized polyacrylate. 13. The non-aqueous coating composition according to claim 11, characterized in that the liquid UV curable resin is an acrylate. 14. The non-aqueous coating composition according to claim 11, characterized in that it also comprises a photoinitiator. The non-aqueous coating composition according to claim 11, characterized in that the ratio of water-swellable polymer in the composition is from about 30% by weight to about 70% by weight and the proportion of UV-curable resin in the composition. composition is from about 30% by weight to about 70% by weight. 16. A method for providing water resistance to the surface of an article characterized in that it comprises: a) preparing a non-aqueous liquid coating composition comprising a water-swellable polymer and a UV-curable liquid resin; b) applying the non-aqueous liquid coating composition to the surface of the article to form a coated surface; and c) exposing the coated surface to UV light and curing the non-aqueous liquid coating composition to form a water-absorbing and water-resistant layer on the surface of the article. The method according to claim 16, characterized in that the step of applying the non-aqueous liquid coating composition to the surface of the article comprises contacting the non-aqueous liquid coating composition with the surface of the article to form a layer of liquid. non-aqueous liquid coating on the entire surface of the article. 18. The method according to claim 16, characterized in that the UV light has a wavelength of about 200 nanometers to about 450 nanometers. 19. A reinforcing fiber material formed in accordance with the method of claim 16. 20. A reinforcing fiber according to claim 19, which is prepared with an aminosilane before the coating is applied. 21. A composite article formed in accordance with the method of claim 16. 22. A reinforced fiber product formed in accordance with the method of claim 16. 23. An article having at least one surface covered by a curable coating. by UV and water resistant comprising: a silane; a water-swellable polymer; and a liquid UV curable resin.