MXPA00002980A - Flexible epoxy sound damping coatings - Google Patents

Abstract

The invention is a sprayable coating having noise vibration and harshness reduction or absorption properties. Such composition comprises from 10 to 60 percent of the flexible epoxy resin, from 5 to 40 percent by weight of a rigid epoxy resin formulation, and a curing agent for the epoxy moieties of the two resins. In another embodiment, the invention is a method of coating a substrate to reduce the impact of noise vibration and harshness on the substrate or users of the substrate, which process comprises spraying the above defined composition onto a substrate and curing the resin on such substrate. In yet another embodiment the invention is a coated substrate described herein before having enhanced noise vibration and harshness properties. The coatings of the invention provide for good noise and vibration properties, excellent corrosion resistance and abrasion resistance. The process of the invention allows for coating irregular shaped object in an easy manner.

Description

FLEXIBLE COATINGS OF EPOXY SOUND ATTENUATION This application relates to flexible epoxy coatings which have sound attenuation properties and to processes for applying such coatings to substrates. Many transportation vehicles, electronic devices, and machines are subject to noise and vibration due to the environments in which they are placed or used. Said noise and vibration may present problems in its use or its function and may annoy or harm the users of such devices or apparatuses. Therefore, there is a need to reduce the impact of such noise and vibration on the devices, devices and users thereof. In many applications, noise and vibration are reduced by placing or fixing such extensional vehicles or attenuators. Extensional attenuators are pads of mixed materials comprised of a polymer or viscoelastic resin, filler and layer of additive composition having on one side of the layer a pressure-sensitive or heat-melting adhesive. These apply to the vibration substrate. Such plates are difficult to fix or configure around irregularly shaped parts, such as the interior of automobiles. In addition, certain coatings are placed on, or sprayed onto, portions of the undesired exterior painted surfaces of such transport vehicles. Such coatings are usually used for corrosion protection providing abrasion resistance or stone impact for painted surfaces. Usually, such coatings are based on rigid elastic polyvinyl chloride and do not provide significant reduction of noise and vibration. In some embodiments, epoxy or modified epoxy resin formulations are used as electro-deposit coatings for corrosion protection. Unfortunately, epoxy or modified epoxy formulations usually form fragile or highly entangled networks, in thicknesses that have limited effect with respect to the reduction of noise and vibration impact on the user of said devices. What is needed is a multifunctional coating which provides noise and vibration reduction in combination with corrosion and abrasion protection properties. What is additionally needed is such a coating that can be sprayed and can be easily placed or coated on irregularly shaped objects. The invention is a multifunctional coating that can be sprayed, which has noise attenuation and vibration or absorption properties. Said composition comprises from 10 to 60 percent of the flexible epoxy resin, from 5 to 40 weight percent of an epoxy resin formulation based on liquid bisphenol, and a curing agent for the epoxy portions of the two resins .

In another embodiment, the invention is a method for coating a substrate in order to improve the noise and vibration properties of the substrate, said process comprising spraying the above-defined composition onto a substrate and curing the resin on said substrate. In yet another embodiment, the invention is a coated substrate described below having improved attenuation of noise and vibration. The coatings of the invention provide good attenuation of noise and vibration, excellent resistance to corrosion, impact resistance and resistance to abrasion. The process of the invention makes it possible to coat irregularly shaped objects in a cost-effective manner and allows the entire surface of the coating to be brought into contact with the substrate. The important thing in the development of a coating which has good sound-abatement properties, abrasion resistance, impact resistance, corrosion resistance and substrate drying is the selection of epoxy resins used in the formulation or coating. More particularly, a balance of flexible epoxy resins and rigid epoxy resins achieves the desired results. As used herein, rigid epoxy resins refer to epoxy resins having portions of bisphenol in the base structure of the epoxy resins. Representative of preferred bisphenol resins useful in this invention are those described in U.S. Patent 5,308,895, in column 8, line 6 and represented by Formula 6. Preferably, the rigid epoxy resin is a liquid epoxy resin or a mixture of a solid epoxy resin dispersed in a liquid epoxy resin. The most preferred rigid epoxy resins are epoxy resins based on Bisphenol-A and epoxy resins based on Bisphenol-F. Flexible epoxy resins, as used herein, refer to epoxy resins having elastomeric chains in the structure of the base. Representative of such elastomeric chains are polyether chains which are preferably prepared from one or more alkylene oxides, representative examples of these flexible epoxy resins are those described in US Patent 5,308,895 at column 8, line 9 and formula 9 and the following description of it. Preferably, the flexible epoxy resin contains in its base structure ethylene oxide, propylene oxide or a mixture of the same. The mixture of flexible and rigid epoxy resins should be such that the peak glass transition temperature of the formulation, as determined by dynamic mechanical measurements of the loss modules, is -30 ° C or higher and preferably 10 ° C or older. Preferably, the peak glass transition temperature is 100 ° C or less and more preferably 50 ° C or less. In a preferred embodiment, the glass transition should be a wide and high glass transition with respect to temperature and frequency, preferably the glass transition temperature range is greater than 80 ° C and more preferably 100 ° C. Preferably, the flexible epoxy resin is present in the formulation in an amount of 10 weight percent or more, more preferably 20 weight percent or more, still more preferably 24 weight percent or greater based on the weight of the formulation. Preferably the amount of the flexible epoxy resin present in the formulation is 60 weight percent or less and more preferably 50 weight percent or less. A preferred flexible epoxy resin is DER ™ 732 epoxy resin available from The Dow Chemical Company. The amount of rigid epoxy resin present is preferably 5 percent by weight or greater and more preferably 10 percent by weight or greater based on the weight of the formulation. The amount of rigid epoxy resin present in the formulation is preferably 40 weight percent or less and more preferably 30 weight percent or less based on the weight of the formulation. The formulation must have a viscosity such that the formulation is sprayed using an airless spray which atomizes the formulation. Preferably, the formulation has a viscosity of 150,000 centipoise or less and more preferably 100,000 centipoise or less. The formulation further comprises a curing agent for the epoxy resin. The curing agent can be any curing agent useful with epoxy resins and known to those skilled in the art. Representative curing agents are described in U.S. Patent 5,308,895 in column 11, line 8 for column 12 line 47. More preferably, the curing agent is a finished amine polyether, such as amine terminated polyether Jeffamine available from Huntsman Chemical, anhydrides, including dianhydrides, and ciandiamines or dicyandiamines and derivatives thereof. The most preferred curing agents are dicyanadiamides and derivatives thereof. The option of the healing agent will affect the shape of the composition, whether or not it is a one-part or two-part composition, storage stability, final performance properties and the curing temperature of the composition. For a two component composition, a finished amine polyether or an anhydride curing agent can be used. For a one component formulation, a dicyanamide curing agent can be used. The curing agent in relation to the epoxy resin is used in an amount such that the ratio of epoxy groups to epoxy reactive groups is from 0.7 to 1 to 1.3 to 1. The curing agent may be present in an amount of 0.5. to 7 weight percent based on the amount of the total formulation. It is preferable that there is a slight excess of portions of epoxy to reactive portions of epoxy such that the scale is from 1.05 to 1 to 1.1 to 1. The composition may further comprise a catalyst for the reaction of an epoxy resin with a Epoxy curative compound. Such catalysts are well known to those skilled in the art, and include those described in the U.S. Patent. ,344,856. The preferred classes of catalysts are ureas, imidazoles, and boron tialides, with ureas being the most preferred catalysts. Of boron tialides, boron trifluoride is most preferred because formulations using this catalyst demonstrate significantly better stability when compared to the other boron tialurides. The amount of catalyst used may vary depng on the desired reactivity and storage stability. Preferably, the catalyst is present in an amount of 0.1 to 5 weight percent based on the weight of the formulation. The formulation may also contain a plasticizer to modify the rheological properties to a desired consistency. The plasticizer should be free of water, be inert to isocyanate groups, and compatible with the polymer. Said material can be added to the reaction mixtures to prepare the prepolymer or the adduct, or to the mixture to prepare the final formulation, but preferably it is added to the reaction mixtures to prepare the prepolymer, in such a way that the mixtures can be mixed and handled more easily. Suitable plasticizers and solvents are well known in the art and include dioctyl phthalate, dibutyl phthalate, a partially hydrogenated terpene commercially available as "HB-40", trioctyl phosphate, trichloropropyl phosphate, epoxy plasticizers, toluene sulfamide, chloroparaffins, esters of adipic acid, xylene, 1-methyl-2-pyrrolidinone and toluene. The amount of plasticizers used is sufficient to give the desired rheological properties and to disperse the components of the formulation. Preferably, the plasticizer is present in an amount of 0 weight percent or more, more preferably 0.5 weight percent or more based on the formulation. The plasticizer is preferably present in an amount of 30 weight percent or less, more preferably 20 weight percent or less and even more preferably 10 weight percent or less based on the weight of the formulation. The formulation may also comprise one or more fillers.

Fillers are used to control viscosity, rheology, storage stability, specific gravity and cured performance properties, such as vibration attenuation, corrosion resistance, impact resistance and abrasion resistance. The fillers can be spherical or laminated. As used herein, laminate means that the particles have a high aspect ratio. Fillers with high aspect ratio include talc, mica and graphite. The preferred high aspect ratio fillers include Phologopite mica having an average particle size of 20 to 70 microns (microns) and more preferably 50 microns (microns). High aspect ratio fillers are used to control the vibration attenuation properties. Spherical fillers include carbonates. Spherical fillers are used to control density and rheology, viscosity and cost. Preferably, a pack of a spherical filler such as calcium carbonate and a filler of high aspect ratio are present. Preferably, the spherical filler is present in an amount of 0 percent by weight or greater, and more preferably 10 percent by weight or greater. Preferably, the spherical filler is present in an amount of 50 weight percent or less and more preferably 30 weight percent or less. Preferably, high aspect ratio fillers are present in an amount of 5 percent by weight or greater, and more preferably in an amount of 10 percent by weight or greater. Preferably, high aspect ratio fillers are present in an amount of 40 weight percent or less and more preferably in an amount of 30 weight percent or less. In another modality, the formulation, in addition, may comprise a reactive diluent such as mono-functional epoxide and other reactive diluents known to those skilled in the art. A preferred reactive diluent is tertiary butyl glycidyl ether. The formulation of the invention may be a two-part formulation, a part depending on the curing agent and at temperatures at which the curing agent begins to cure the epoxy resin. If the curing agent is reactive at room temperature, the formulation should be a two part formulation and if the curing agent is reactive at significantly higher temperatures, the formulation can be a one or two part formulation initiating healing exposing the formulation to heat. The process of the invention involves contacting the formulation with a substrate. The substrate can be any substrate for which protection against corrosion and protection against abrasion and attenuation or abatement of sound is desired. Such a substrate can be metal, wood, plastic, fiber-reinforced plastic. The formulation can be used in a wide variety of industries including the automotive industry, the electrical appliance industry and the construction industry. The formulation is particularly advantageous in that it is sprayable and can be sprayed onto irregularly shaped objects such as automobile bodies. The formulation of the invention can be contacted with the substrate by any means known in the art, for example by painting, spraying or dispersing the same on the substrate. Preferably, the composition is sprayed onto the substrate. Preferably, a high volume, high pressure airless sprayer is used which atomizes the composition. More preferably, the airless sprinkler has a ratio of 45 to 1 with a double-ball valve or revision style pump and with an inlet air pressure of 344 kPa to 621 kPa. Once the formulation is contacted with the substrate, the formulation is allowed to cure. For these compositions where curing at room temperature occurs, no further steps should be taken. Curing at room temperature generally occurs with polyether-terminated anhydride and amine curing agents. With ciandiamine or diaciandiamide curing agents the coated substrate must be exposed to elevated temperatures to effect cure. 1,2-Dodecyl anhydride can be used in one-part compositions and cured at elevated temperatures. Preferred lower cure temperatures are generally 0 ° C or higher, more preferably 40 ° C or more and even more preferably 60 ° C or more. Preferably, the curing temperature is 190 ° C or less, more preferably 150 ° C or less and more preferably 140 ° C or less. Another aspect of the invention is a substrate as described below having on it an abrasion resistant sound attenuation coating, corrosion resistant coating. Preferably, the coating is 1.5 mm or more and preferably the coating is 2.5 mm or less. The coating of the invention preferably provides a mixed material loss factor of 0.05 or greater measured using the mixed material loss factor test protocol given by SAE J1637 with a 2 mm coating. More preferably, the peak loss modulus of the coating must be greater than 300 units on the desired operating temperature scale. As used herein, the following test protocol was used to test coated substrates of the invention: sound abatement properties are measured according to SAE J1637 Laboratorv Measurement Of The Pampina Properties Of Materials On A Supporting Steel Beam and / or dynamic mechanical analysis (delta tangent at 2 Hz resonant frequency over a temperature sweep at 5 ° C / minute); Corrosion resistance is measured by subjecting the coated panels to salt mist for 336 hours, 168 hours in 100 percent relative humidity at 38 ° C and 336 hours of heat aging at 70 ° C and the loss of adhesion or other critical properties; Abrasion resistance was measured according to ASTM D968-93 with modified abrasive; Impact resistance per stone is measured with a Gravelometer using 8-12 mm stones and coated panels balanced at -30 ° C according to SAE J400 Method II Specific Modalities. The following examples were provided to illustrate the invention, but are not intended to limit the scope thereof. All parts and percentages are by weight unless otherwise indicated. In the following examples the coatings were prepared by batch mixing the components under high speed, high shear agitation. The process includes three steps: all liquid resins, curative fillers and laminates are first mixed for 20 minutes and degassed at 30 mmHg; spherical fillers and glass spheres are added and the mixture is combined for 20 minutes and degassed at 30 mmHg; then fumed silica is added and the mixture is combined for 10 minutes and degassed at 30 mmHg. The coatings are applied to the substrates formed of cold-rolled, electro-coated steel panels by the following procedure. The material was applied to the panels either ally by a descending pull bar or by spraying with an airless spray pump operating at 0.552 mPa inlet pressure and 24.8 mPa dynamic pressure attached to a 9.5 mm flexible connection hose and a 0.20 mm self-cleaning nozzle. The components of the tested coatings are compiled in the following tables. Unless otherwise indicated, all samples of the coatings on the panels were cured for 30 minutes at 163 ° C. The following tests were performed on the samples: press flow viscosity; tensile strength and elongation ASTM D638; shear strength ASTM D1002; heat graduation; resistance to salt spray; resistance to moisture; splinter resistance, abrasion resistance ASTM D968-93; SAE J1637 attenuation at 0, 20 and 40 ° C. The viscosity of the press flow is made by pressing 20 g of the material under a pressure of 276 kPa, through an orifice that has a diameter of 0.13 cm at 25 ° C and recording the time it takes the material to pass through the hole . The heat graduation test is performed on a 0.05 cm film adhered to an electrocoated cold rolled steel substrate, heating it to 70 ° C and relative ambient humidity for 336 hours. The salt spray test is performed by exposing a 0.05 cm film on a cold-rolled, electro-coated steel substrate at 100 percent relative humidity at 38 ° C for 168 hours. The chipping resistance test (impact resistance of stone) was measured with a Gravelometer using 8-12 stones and coated panels balanced at -30 ° C according to SAE J400 Method II.

Example 1 Example 1 demonstrated the multifunctional attributes of the epoxy coating, which provides the physical and mechanical properties necessary for protective coatings as well as vibration attenuation.

Example 2 Example 2 demonstrated attenuation improvement obtained by the use of high aspect ratio talcum while maintaining low viscosity and good rheology necessary for the spray application.

Examples 3 and 4 Examples 3 and 4 demonstrated attenuation improvement obtained through the use of a high aspect ratio and mica fill talc combination while maintaining low viscosity and good rheology needed for spray application.

Examples 5 and 6: Examples 5 and 6 showed improvement of attenuation obtained by the use of mica with high aspect ratio while losing viscosity and rheology necessary for spray application. Example 7 Temp loss module (V) @ pico (MPa) 326 @ 41 306 @ 32 Example 7 demonstrated the effect of the plasticizer on peak attenuation and change in attenuation temperature scale.

Example 8 Example 8 demonstrated the ability to change peak attenuation over the desired operating temperature scale without significantly affecting the attenuation performance.

Example 9 and 10 Examples 9 and 10 demonstrated the effect of the glass spheres on the density of the material while showing no negative effect on the viscosity and a positive effect on the peak attenuation efficiency. Example 11 The following components are mixed in a Ross mixer; 113.4 grams of bisphenol A epoxy resin (DER ™ 331 available from The Dow Chemical Company), 170.1 grams of a polypropylene oxide based on epoxy resin (DER ™ 732 available from The Dow Chemical Company), 283.6 grams of succinic anhydride of dodecyl available from Lonza Inc., 31.7 grams of CAB-SIL TS 720 a hydrophobic smoked silica available from Leepoxi Plastics, Inc.), 157.2 grams of calcium carbonate and 240 grams of talc. The coating is applied to a cold-rolled electro-coated steel panel with a thickness of 15 mm nominally. The applied coating is cured at 140 ° C for 30 minutes. The coating showed a press flow viscosity of 21 seconds, a tensile strength of 8.37 mPa and an elongation of 55 percent. The sample did not develop any chipping, lifting or loss of adhesion during the chipping resistance test.

Claims (10)

1. CLAIMS 1. A spray epoxy composition useful in coating substrates comprising one or more flexible epoxy resins in amounts of 10 to 60 weight percent, one or more rigid epoxy resins in amounts of 5 to 40 percent by weight. weight and one or more curing agents for the epoxy resin in an amount of from 0.5 to 5 weight percent. A composition according to claim 1, wherein the epoxy rigid resin is an epoxy resin based on liquid bisphenol and the flexible epoxy resin is a polyester based on epoxy resin. 3. A composition according to claim 1 or 2, wherein the curing agent is a finished polyether of amine, an anhydride, a ciandiamine or a dicyandiamine. 4. A composition according to any of claims 1 to 3, which further comprises a catalyst for the reaction of an epoxy compound with an epoxy curative compound. 5. A composition according to any of claims 1 to 4, wherein the catalyst is a dimethyl phenyl urea, imidazole or a boron tialide. 6. A composition according to any of claims 1 to 5, which further comprises a spherical and a laminated filler. 7. A composition according to claim 6, which comprises A) from 10 to 60 weight percent of a flexible epoxy resin; B) from 5 to 40 weight percent of a rigid epoxy resin; C) 0.5 to 5 weight percent of a curing agent for the epoxy resin; D) from 0.5 to 30 weight percent of a plasticizer. 8. Method for coating a flexible epoxy sound attenuation resin that is coated onto a substrate which comprises A) coating a composition according to any of claims 1 to 7 on a substrate; and B) curing the composition at a temperature of 0 ° C to 190 ° C. 9. A method according to claim 8, wherein the coating is applied by means of spray. 10. A substrate coated with a composition of claim 1, wherein the composition provides sound attenuation properties.