MXPA00011123A - Acoustic dampening compositions containing recycled paint polymer - Google Patents

Abstract

Acrylic resin-based plastisol compositions are improved by the incorporation of recycled paint polymer containing uncured resin (i.e., substances containing functional groups capable of undergoing chemical reaction). The compositions may be used to apply coatings to stiff articles having a tendency to vibrate such as metal automobile parts and the like. Such coatings are effective in suppressing mechanical vibration, reducing the noise of particle impact, and/or lowering the amount of air vibration in a cavity.

Description

"ACOUSTIC SHOCK COMPOSITIONS CONTAINING RECYCLED PAINT POLYMER" BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to plastisol compositions based on acrylic resins such as polymethyl methacrylates, which are capable of being sprayed into inferior automotive bodies and the like. More particularly, the invention relates to the use of a recycled paint polymer containing uncured resin to improve the acoustic damping performance of these plastisols.

DISCUSSION OF THE RELATED TECHNIQUE Almost all currently produced vehicles, machines and appliances consist of relatively thin metal coatings or plates. These thin plates often have a pronounced tendency to vibrate due to the effect of mechanically movable parts or motors in operation. This vibration leads to the undesirable generation of sound. Another source of noise, particularly in cars and other vehicles driving on the road or other surface, is garbage such as gravel, sand, water and the like that is thrown upward by the wheels of a vehicle against the wheel wells and the lower body of the vehicle. The sound can also be generated by the vibration of the air inside the cavities of a moving vehicle. Numerous ways in which the noise associated with solid vibrating articles can be reduced have been proposed in the past. A common approach is to cover the thin metal plating used in vehicles, appliances and other machinery with a layer of a coating that absorbs or absorbs sound. Visco-elastic coatings based on various polymers have often been used for these purposes. Plastisols based on PVC (polyvinyl chloride), for example, have been modified to have better sound-proofing properties on the working temperature scale from -20 ° C to + 60 ° C, than the "spray-on" coating materials conventional PVC-based resins (see, for example, U.S. Patent No. 5,756,555) Acoustically active sprayable plastisol compositions based on styrene copolymers, alkyl methacrylate homopolymers, and / or methyl methacrylate copolymers are also known US Patent Number 5,741,824 (Butsc bacher et al.) Even though these materials are - Effective as soundproof coatings, there is still a need for further improvements in the field. For example, it would be desirable to develop alternative coating formulations that have a lower production cost or are even better for noise and vibration suppression.

COMPENDIUM OF THE INVENTION The invention provides a plastisol composition useful for suppressing mechanical vibration, reducing the impact noise of the particles or decreasing the vibration of the air in a cavity. The composition consists of one or more acrylic resins such as pdlimethyl methacrylate, a recycled paint polymer containing uncured resin, one or more plasticizers and one or more filler or filler materials. Buffer constructions comprising at least one layer of the plastisol composition applied to a solid vibrating article are also provided. In addition, a method of coating a solid vibrating article is provided to suppress mechanical vibration, reduce the impact noise of the particle, or decrease the vibration of air in a cavity of the vibrating solid article, the method comprising applying at least a layer of the plastisol composition described above to the vibrating solid article and gelling (curing) the plastisol composition, preferably by heating. A coating obtained by gelling is also provided by means of the present invention. (curing) the plastisol composition.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph showing the relationship between the loss factor and the temperature for the plastisol compositions discussed in the Examples | - and 2 and Comparison Examples 3 and 4. Figure 2 provides similar information for different thicknesses of the plastisol composition of Example 5.

DETAILED DESCRIPTION OF THE INVENTION The plastisol composition contains an effective amount of one or more acrylic resins, ie, the polymers formed by polymerizing the monomers branched to the α, β-unsaturated carboxylic acids. These monomers can be homopolymerized or copolymerized, and ßea with other monomers based on α, β-unsaturated carboxylic acids or with other types of monomers such as olefins, vinyl esters, vinyl aromatics (e.g., styrene) and the like. Preferably, the monomer is an ester of an α, β-unsaturated monocarboxylic carboxylic acid, particularly a lower alkyl ester (e.g., methyl, ethyl, propyl, butyl, including both straight chain and branched chain isomers). The use of esters of acrylic acid and methacrylic acid is preferred, especially aliphatic esters of 1 to 10 carbon atoms. Particularly useful are methyl methacrylate homopolymers and copolymers (e.g., methyl methacrylate / butyl methacrylate copolymers). The acrylic resin is desirably a thermoplastic instead of a thermosetting one, even though the slightly crosslinked acrylic resins can also be used. The glass transition temperature of the acrylic resin used in the invention is preferably at least about 80 ° C, more preferably at least about 100 ° C, and especially preferably at least about 120 ° C. C. The acoustic damping properties of the cured plastisol composition usually improve as the glass transition temperature increases. The use of acrylic resins having lower glass transition temperatures, however, can improve certain other properties such as elongation. The acrylic resin will typically have a number average molecular weight within the range of about 40,000 to 2,000,000 and can be made by free radical polymerization of suspension or emulsion. Preferably, the acrylic resin is in the form of fine particles or a powder when used to prepare the plastisol composition. The morphology of the particle (e.g., surface area, particle size and distribution, porosity) should be selected such that the resulting plastisol has acceptable stability before use (e.g., during storage). Particle sizes from about 0.1 to about 500 microns are generally appropriate. Even though the amount of the acrylic resin in the plastisol composition is not believed to be particularly critical, with the optimum amount varying greatly which depends on the acrylic resin selected, the relative amounts of the other components as well as the properties desired in the Cured plastisol, typically from about 10 percent to about 50 percent by weight of the plastisol composition, will be acrylic resin. A critical feature of the present invention is the incorporation of an amount of a recycled paint polymer containing effective uncured resin to improve the acoustic activity of the plastisol composition compared to a comparable plastisol composition containing an amount of acrylic resin equal to the total amount of the acrylic resin plus the recycled paint polymer in the plastisol composition of the present invention. Stated differently, a sufficient amount of the recycled paint polymer should be replaced by the acrylic resin in the formulation in order to improve the sound-deadening performance of the resulting plastisol composition when cured. Even when this minimum amount will vary from one plastisol formulation to another, depending on a number of factors typically at least about 1 percent of the plastisol composition by weight will be the recycled paint polymer. Generally speaking, no more than about 25 percent of the plastisol composition is the recycled paint polymer, even if higher levels could be used if desired. The recycled paint polymers containing the uncured resin that are used in the plastisol compositions of this invention are well known in the art and are more fully described, for example, in U.S. Patent Nos. 5,160,628, 5,254,263 and 5,880,218, the teachings of which are incorporated herein by reference in their entirety. These materials are obtained from the paint sludge, which is recovered from automotive and similar paint operations as described in the aforementioned patents. Mud paint is a complex mixture, the chemical composition of which is difficult to describe in detail. Uncured polymer resins, pigments, curing agents, surfactants, and other secondary ingredients are known to be present, however, in addition to water and organic solvents. In the automotive industry, for example, paints that are commonly used include modified thermosetting alkyd resins and acrylic resins. The latter resins typically consist of acrylic acid-melamine copolymers or acrylic-isocyanic acid copolymers. Alkyd modified resins are generally obtained from polyalcohols, polybasic acids such as italic acids and monobasic fatty acids and are used in combination with crosslinking agents such as amino resins (including urea and melamine resins). Other paint resin systems frequently used in the automotive industry include phenolic resins, polyurethanes, epoxy resins, and hybrid systems such as acrylic / amino, acrylic / epoxy, alkyd / acrylic, alkyd / epoxy, and polyester / epoxy combinations. Automotive paints are described in greater detail in the chapter called "Coatings" in Volume 3 of the Encyclopedia of Polymer Science and Engineering, Second Edition (published by Wiley-Interscience in 1985). In one embodiment of the present invention, the recycled paint polymer has been recovered from an automotive finishing operation and consists of an acrylic resin. Before use in the present invention, the paint sludge can be processed to remove, or reduce the level of, certain components. For example, paint sludge can be detached (ie, treated with release agents) or concentrated or dried by heating or a similar means to remove water and other volatile substances. In one embodiment, the recycled paint polymer has a volatile content of less than 1 weight percent. In another embodiment, the recycled paint polymer is in the form of a slime powder. In yet another embodiment, the recycled paint polymer is in the form of a mastic (as described, for example, in U.S. Patent No. 5,880,218). However, it is important that this additional processing does not produce the uncured resin in the non-reactive recycled paint polymer. Due to this reason, the addition of - a base to the recycled paint polymer in order to descatalize the polymer, as described in U.S. Patent No. 5,880,218, is preferably avoided. Recycled paint polymer products suitable for use in the present invention are also available from commercial sources such as EP.I of Toledo, Ohio, which sells this material under the trademark "EPIMER 2OOP". One or more plasticizers are also present in the composition-of plastisol and are used in an effective amount to provide a viscosity capable of being worked. That is, a sufficient amount of the plasticizer is used to allow the solid components of the composition (eg, acrylic resin, filler or filler materials) to be applied as a coherent coating to, or adhered to, a solid vibrating article by means of spraying, brush application, immersion or similar means. The amount and type of plasticizer (s) that is selected can also be easily varied to impart the acoustical properties and other desired properties to the final cured plastisol coating. Typically, the levels of the plasticizer will vary from about 10 percent to about 60 percent by weight of the plastisol composition.

Suitable plasticizers are usually any of the plasticizers known in the art as being effective in plasticizing the plastisol compositions. Phthalates, particularly alkyl and aryl phthalates such as dibutyl phthalate, dioctyl phthalate, benzylbutyl phthalate, dibenzyl phthalate, diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), and diundecyl phthalate (DIUP) as well as esters of benzoate such as dibenzoate esters of glycols are preferred. However, other known classes of plasticizers such as C3-C24 esters of adipic, azelaic, sebacic, trimellitic, citric and phosphoric acids, alkyl esters of fatty acids, esters of alkylsulfonic acid of phenols, epoxidized triglycerides, dibenzyltoluene , or diphenyl ether are also appropriate. Of course, mixtures of plasticizers can also be used. The selection criteria for the preferably used plasticizers are determined on the one hand by the types and amounts of acrylic resin, the recycled paint polymer, and the filler or filler, and on the other hand, by the viscosity and gelation conditions. of the plastisol and the acoustic properties and other desired characteristics in the cured coating.

The plastisol compositions of the present invention will also generally contain one or more different filler or filler materials. The filler or filler materials can be used to improve the characteristics of the atmospheric agents, reduce the surface tack or increase the hardness of the molten plastisol film. Any of the known plastisol filling or filler materials can be used including without limitation titanium dioxide, diatomaceous earth, calcium carbonate (which can be coated, ground and / or precipitated), calcium oxide (which can also function as a drying agent), mica, vermiculite, heavy spar, carbon black (which can also function as a pigment), silica (eg, fuming silica, sand), clay, talcum, alumina, bentonite, glass (in the form of powders, fibers, beads, including hollow microspheres, or the like), expanded and / or expandable thermoplastic resin microspheres and the like. Typical filler or filler levels will vary from about 5 percent to about 50 percent by weight of the plastisol composition. The plastisols according to the invention may contain one or more reactive additives in addition to the recycled paint polymer (which itself may contain reactive components) such as, for example, thermosetting resins for example epoxy resins., melamine-aldehyde resins, polyfunctional isocyanates, phenolic resins (e.g., phenol-aldehyde resins) and the like. Typical levels of the reactive additives are from about 0.5 percent to about 5 percent by weight of the plastisol composition. The curatives, crosslinking agents and / or catalysts can be used to cure or cure the reactive additives. For example, polyfunctional amines and alcohols (eg, diamines, glycols, polyether polyols, polyester polyols) can be used in combination with epoxy resins or polyfunctional isocyanates, while acid catalysts can be used to cure resins of melamine-aldehyde. In addition, the plastisols may optionally contain other auxiliary products and additives typically found in plastisol technology, including, for example, adhesion promoters or activators (silanes, titanates, zirconates), pigments, anti-aging agents (stabilizers, antioxidants, inhibitors). corrosion), flow aids (rheological control agents, surfactants), thixotropic agents, and blowing agents. Blowing agents are used when a foamed plastisol coating is desired. Foaming can often improve the vibration damping properties of cured plastisol. Suitable blowing agents are any of the blowing agents known in the art, preferably the organic chemical blowing agents selected from the azo compounds. The N-nitroso compounds, sulfonyl hydrazides, and sulfonyl icarbazides. The activators or accelerators of the blowing agent that reduce the temperature at which the blowing agent decomposes to release the gas can also be incorporated into the plastisol composition. The manner or order in which the previously described components are combined with one another that is not believed to be critical; any of the conventional plastisol preparation methods known in the art can be used. For example, the components can be added simultaneously or in sequence and mixed using a dispersion blade mixer, planetary mixer, kneading style mixer or the like until the desired consistency and uniformity is achieved. Even though the mixing temperature may be slightly elevated to reduce the viscosity, temperatures high enough to cause premature melting or gelling should be avoided clearly.

The plastisol compositions of this invention are suspensions of the acrylic resin (s) and the plasticizer (s). The suspensions are sufficiently fluid (i.e. fluent) to be applied at relatively low temperatures by spraying, paddle dispersion, brush dispersion, dip, or the like to a substrate to be coated, however high enough in viscosity that a layer of the desired thickness can be easily achieved. However, it is also possible to apply multiple layers of plastisol, carry out the cure or increase the thickness of the coating by applying a layer, heating the applied layer to induce gelling or curing, and applying in a similar manner and curing one or more of the additional layers. The thickness of the coating will depend on a number of factors, particularly the end-use application as well as the desired degree of noise reduction, but will typically be from about 0.05 millimeter to about 100 millimeters; and thicknesses of approximately 0.5 mm to approximately 25 mm are also commonly employed. The liquid plastisol that has been applied to the substrate is then converted into a visco-elastic material through exposure to heat or similar media. Temperatures of approximately 50 ° C to 250 ° C (higher - preference, from approximately 100 ° C to 220 ° C) will usually be sufficient for this purpose. Heating is continued for an effective time to at least render the plastisol in a non-liquid or non-sticky manner and more preferably to fully develop the desired properties in the cured coating. This step can also be referred to as "gelation" or "cure". Without wishing to be limited by any theory, it is believed that the heating causes the particles suspended from the acrylic resin to melt or dissolve in the plasticizer. A reaction of the uncured resin in the recycled paint polymer as well as any thermosetting resin present in the plastisol may also be taking place. During cooling, however, a solid coating is obtained which provides excellent sound dampening and exhibits good durability and adhesion to the substrate. The plastisols according to the invention are particularly suitable as coatings for steel and other metal sheets. For example, they can be used as coatings on the lower bodies of automobiles, trucks, buses or other vehicles. In a particularly desirable application, the plastisol composition is sprayed to the underside of a car (including, for example, the metal cupper and the wheel wells) and cured to provide a coating that effectively reduces sound emission and of mechanical vibration that leaves that area of the car during use. The plastisol composition can of course be applied to an individual automotive part (e.g., fender, oscillating panel) before assembly.

EXAMPLES Example 1 and Example 2 illustrate embodiments of the acoustic buffer compositions of the present invention differing primarily by including a small amount of the chemical blowing agent (oxybisbenzenesulfonyl hydrazide) in Example 2. The components of each of these examples are listed in Table 1. The presence of the chemical blowing agent results in the composition expanding to approximately 50 volume percent when cured (gelled). The compositions were prepared using normal plastisol mixing procedures and cured using normal automotive paint conditions of 30 minutes at 130 ° C. The loss factor of each composition when cured was measured in accordance with ASTM E756. Figure 1 is a trace of the loss factor across the temperature scale from -10 ° C to + 40 ° C. For comparison purposes, an acoustic buffer composition that did not contain any recycled paint polymer was prepared and tested as described in Example 1 (Comparison Example 3). The amounts of each of the polymethacrylate acrylic resins in the formulation were increased by 5 weight percent to compensate for the removal of the recycled paint polymer. It will be readily apparent from Figure 1 that the cured composition of Comparison Example 3 was significantly less effective at dampening noise, as measured by the loss factor than the composition of Example 1 containing the recycled paint polymer. Comparison Example 4 employed a lower body coating based on TPN 4869 PVC which can be obtained commercially from Henkel Surface Technologies and which does not contain the recycled paint polymer. Although the TPN coating 4869 exhibited a higher loss factor than the compositions of Examples 1 and 2 at low temperatures, at room temperature and higher the compositions of the present invention were more effective in reducing noise. Example 5 illustrates yet another embodiment of the present invention that uses a melamine-formaldehyde resin instead of the epoxy resin used in Example 1 and in Example 2, mica as a filler or filler, dibenzoate plasticizers of glycol instead of the phthalate-based plasticizers as in Examples 1 and 2, a sulphonic acid curing agent and different rheology control additives than those used in Examples 1 and 2. Details of the formulation of Example 5 were provided in Table 2. Different thicknesses of the composition of Example 5 were prepared and tested in the same manner as in the previous examples. Figure 2 shows how the observed loss factor varies with both temperature and film thickness (tested at 200 Hz).

Table 1 Factory Name Chemical Substance Proportioner Direction (by weight) Example 1 Example 2 HUBERCARB Q325 20.60% Carbonate 20.60% Huber Quincy, IL Calcium SANTICIZER 261 Alkyl Phthalate 8.00% 8.00% Monsanto Itasca, IL Benzyl ROHAMERE 4858F Polymethacrylate 16.00 % 16.00% Creanova Darmstadt Germany EPIMER 200 P Paint Polymer 10.00% 10.00% EPI Toledo, OH Recycled ROHAMERE 4899F Polymethacrylate 11.00% 11.00% Creanova Darmstadt Germany ANCAREZ 2289 Resin Mix 2.00% 2.00% Air Allentown, Epoxy Products PA Quicklime Calcium Oxide 1.00% 1.00% Mississippi Alton, Lime IL SOCAL 322 Calcium Carbonate 6.50% 5.00% Solvay France Coated MHHPA Acid Anhydride 0.50% 0.50% Huis Piscata a, Methylhexahydro- NJ Phthalic JAYFLEX 77 Diester Phthalate 10.00% 10.00% Exxon Houston, TX ELFTEX 12 Carbon 1.00% 1.00% Cabot Boston , MA HDK N 20 Silicon Dioxide 0.40% 0.40% acker Munich, Fumante Germany JAYFLEX DINP Phthalate ester 13.00% 13.00% Exxon Houston, TX BBSH Hydrazide 0 1.50% Rit-Pleasantville Oxibisbencensulfonyl Chem NY Table 2 (Example 5) Factory Name Chemical Substance Percent Provider Address (by weight) NACURE 2500 Sulphonic Acid 0.205 King Nor alt, Industries CT BENZOFLEX 9-99 Dibenzoate 26.00% Velsicol Rosemont, Glycol IL ROHAMERE 4944 Polymethyl Acrylate 12.00% Rohm Darmstadt, Germany EFIMER 200 P Polymer of Pin10.00% EPI Toledo, OH Tura Recycled ROHAMERE 1001F Polimetacrilato 15.00% Rohm Darmstadt, Germany DISPERPLAST 181 Ester of Acid 1.00% BYK Carboxilic / Long Chain Alcohols Quicklime Calcium Oxide 1.005 Mississippi Alton, IL Lime SOCAL 322 Calcium Carbonate 6.00Í "Solvay France Coated RESIMENE 747 Melamine Resin- 2 2..0000 %% Solutia St. Loius, formaldehyde MO M1NERALITE 3X Mica 16.80% Mineral Kershaw, Mining sc ELFTEX 12 Carbon 1.00% Cabot Boston, MA A-FLAKE 800 Mica 4.00% Zeme Spruce Pine, NC BENZOFLEX 2088 Glycol Dibenzoate 5 5.0000% Velsicol Rosemont, IL

Claims (36)

CLAIMS:

1. A composition useful for suppressing mechanical vibration, reducing the impact noise of the particles, or decreasing the vibration in a cavity, the composition being composed of: (a) one or more acrylic resins; (b) a recycled paint polymer containing uncured resin; (c) one or more plasticizers; and (d) one or more filler or filler materials.

2. The composition of claim 1, further comprising one or more blowing agents.

3. The composition of claim 1, further comprising one or more activators or adhesion promoters.

4. The composition of claim 1, further comprising one or more thermosetting resins.

The composition of claim 1, wherein at least one of the acrylic resins is selected from the group consisting of homopolymers of methyl methacrylate and copolymers of methyl methacrylate.

6. The composition of claim 1, wherein the uncured resin consists of an acrylic resin. -

7. The composition of claim 1, wherein the recycled paint polymer contains uncured resin in the form of a mastic.

The composition of claim 1, wherein the recycled paint polymer containing the uncured resin has a volatile content of less than 1 weight percent.

9. The composition of claim 1 wherein the recycled paint polymer containing uncured resin is in powder form.

The composition of claim 1, characterized in that it is essentially free of homopolymers and copolymers of vinyl chloride.

The composition of claim 1 wherein at least one of the plasticizers is a phthalate ester.

12. An acoustic damping composition consisting of: (a) about 10 percent to about 50 weight percent of one or more acrylic resins, wherein at least one of the acrylic resins is selected from the group consisting of homopolymers and methyl methacrylate copolymers; (b) from about 1 percent to about - 25 weight percent of the recycled paint polymer containing the uncured resin; (c) about 10 percent to about 60 weight percent of one or more plasticizers; and (d) about 5 percent to about 50 percent by weight of one or more filler or filler materials.

13. The acoustic buffer composition of claim 12 further comprising one or more organic chemical blowing agents.

The acoustic buffer composition of claim 12 further comprising one or more activators or adhesion promoters.

15. The acoustic buffer composition of claim 12 further comprising one or more thermosetting resins, at least one of the thermosetting resins is selected from the group consisting of epoxy resins and melamine-aldehyde resins.

16. The acoustic buffer composition of claim 12 characterized in that it is essentially free of homopolymers and copolymers of vinyl chloride.

17. The acoustic damping composition of claim 12 wherein the uncured resin consists of an acrylic resin. 2

18. The acoustic buffer composition of claim 12 wherein the recycled paint polymer is in the form of a mastic.

19. The acoustic buffer composition of claim 12 wherein the recycled paint polymer containing the uncured resin has a volatile content of less than 1 weight percent.

20. The acoustic buffer composition of claim 12 wherein the recycled paint polymer is in powder form.

21. A damping construction comprising at least one layer of the acoustic damping composition of claim 1 applied to a solid vibrating article.

22. A damping construction of claim 21, wherein the solid vibrating article is a metal automotive component.

23. The damping construction of claim 21 wherein the layer of the acoustic damping composition has a thickness of about 0.05 millimeter to about 100 millimeters.

24. The damping construction of claim 21, wherein the layer of the acoustic damping composition has gelled by heating. -

25. A damping construction comprising at least one layer of the acoustic damping composition of claim 12 applied to a solid vibrating and gelled article by heating.

26. The cushion construction of claim 25, wherein the solid vibrating article is a metal automotive component.

27. The damping construction of claim 25, wherein the layer of the acoustic damping composition has a thickness of about 0.5 millimeter to about 25 millimeters.

28. A method for coating a solid vibrating article to suppress mechanical vibration, reduce the impact noise of the particle, or decrease the vibration of air in a cavity of the solid vibrating article, the method comprises applying at least one layer of the composition of claim 1 to the vibrating solid article and gelling the composition.

29. The method of claim 28, wherein the composition is applied by spraying.

30. The method of claim 28, wherein the composition is gelled by heating.

31. The method of claim 28 wherein the solid vibrating article is a metal automotive component. - -

32. The method of claim 28 wherein the layer of the composition has a thickness of about 0.05 millimeter to about 100 millimeters.

33. A method for coating a metal automotive component to suppress mechanical vibration, reduce particle crash noise, or decrease air vibration in a cavity of the automotive metal component, the method comprising spraying at least one layer of metal. the composition of claim 12, towards the metal automotive component and gelling the composition by heating.

34. The method of claim 33 wherein the layer has a thickness of about 0.5 millimeter to about 25 millimeters.

35. A coating obtained by gelling the composition of claim 1.

36. A coating obtained by heating the composition of claim 12 for a period of time and at a temperature effective to gel the composition.