Liquid-applied sound-attenuating composition

Abstract

The present invention relates to a composition comprising an aqueous dispersion of acrylic polymer particles, paraffin wax, graphite particles, and extender particles, which is useful for making low water absorption coatings for liquid applied sound attenuation applications.

Description

[Background technology]

[0001] The present invention relates to a composition suitable for liquid-applied sound attenuation applications, and more particularly to a composition that forms a coating having excellent water resistance.

[0002] Damping materials are used to reduce vibrations in rigid structures and decrease noise. In automobiles, two main vibration damping technologies are dominant: bitumen pads and liquid-applied sound damping (LASD) coatings derived from aqueous latex. Bitumen pads, a low-cost alternative widely used in the 20th century, exhibit relatively low damping performance and require laborious manual application. LASD coatings, on the other hand, have gained a considerable market share because they can be rapidly applied by robotic spraying technology. Furthermore, LASD coatings exhibit superior damping characteristics, environmental, health, and safety (EH&S) profiles, and lower densities. In short, these advantages have led automotive OEMs to increasingly utilize LASD for noise vibration and harshness (NVH) management, which is currently lacking in bitumen pads. International Publication No. 2018 / 062546(A1) describes aqueous dispersions of polymer particles suitable for vibration damping applications. While improvements have been reported in suppressing blistering, there is no mention of water resistance. Developing LASD coatings with superior water resistance comparable to bitumen pads remains a need in this field. Water-resistant LASD coatings could facilitate customer adoption of this technology. Furthermore, improved water resistance would allow LASD coatings to be used in new application areas, such as within vehicle wheel wells. Therefore, developing aqueous dispersions of polymer particles that can be incorporated into LASD coatings that are water-resistant, exhibit excellent appearance, and maintain high vibration damping performance would represent an advance in this field. [Overview of the project]

[0003] This invention relates to a z-average particle size in the range of 50 nm to 500 nm, and a calculated T in the range of -25°C to 30°C. g The present invention addresses the needs in the art by providing a composition comprising an aqueous dispersion of acrylic polymer particles having a specific value, paraffin wax, filler particles, and a rheology modifier, wherein the volume concentration of the pigment in the composition is in the range of 40 to 70, and the composition has a Brookfield viscosity in the range of 200,000 cP to 20,000,000 cP when not under shear conditions. The composition of the present invention is useful for reducing water absorption in coatings for LASD applications. [Modes for carrying out the invention]

[0004] This invention relates to a z-average particle size in the range of 50 nm to 500 nm, and a calculated T in the range of -25°C to 30°C. g A composition comprising an aqueous dispersion of acrylic polymer particles having a certain value, paraffin wax, filler particles, and a rheology modifier, wherein the volume concentration of the pigment in the composition is in the range of 40 to 70, and the composition has a Brookfield viscosity in the range of 200,000 cP to 20,000,000 cP when not under shear conditions.

[0005] As used herein, the term acrylic polymer particles (or acrylic latex particles) refers to acrylic polymer particles or styrene-acrylic polymer particles. The polymer particles are preferably film-forming at ambient temperature, and therefore the polymer particles are calculated by Fox's equation T g The temperature is preferably 30°C or lower, preferably 20°C or lower, more preferably 5°C or lower, and -25°C or higher, more preferably -10°C or higher. Preferably, the polymer particles are methyl methacrylate (MMA, T g (=105℃) or styrene (STY, T) g The structural unit of (=100℃) and ethyl acrylate (EA, Tg g = -22°C), butyl acrylate (BA, T g g = -54°C), 2-ethylhexyl acrylate (2-EHA, T g g = -70°C), and 2-propylheptyl acrylate (2-PHA, T g g = -68°C), and at least one monomer selected from the group consisting of the above.

[0006] The term "structural unit" is used herein to describe the residue of the recited monomer after polymerization. For example, the structural unit of MMA is as shown below:

[0007]

Chemical Formula

[0008] The polymer particles comprise structural units of an ethylenically unsaturated acid monomer, such as a carboxylic acid monomer and a phosphorus-containing acid monomer, in an amount of preferably from 0.1% by weight, more preferably from 0.2% by weight, most preferably from 0.3% by weight, up to 6% by weight, more preferably up to 4% by weight, most preferably up to 3% by weight. Examples of suitable carboxylic acid monomers include acrylic acid, methacrylic acid, and itaconic acid. Examples of suitable phosphorus-containing acid monomers include phosphonates and dihydrogen phosphate esters of alcohols which alcohols contain a polymerizable vinyl or olefinic group, or are substituted with such groups. Preferred dihydrogen phosphate esters are phosphates of hydroxyalkyl acrylates or methacrylates, including phosphoethyl methacrylate (PEM) and phosphopropyl methacrylate.

[0009] The concentration of polymer particles is preferably in the range of 10 to 25% by weight, based on the weight of the composition. The acrylic polymer particles preferably have a z-average particle size in the range of 80 nm to 250 nm, as measured by dynamic light scattering. In one embodiment, the acrylic polymer has a number-average molecular weight in the range of 10,000 to 40,000 g / mol, as measured by gel permeation chromatography, which is detailed below.

[0010] Paraffin wax consists of 10 to 40 repeating ethylene units: (CH2CH2) n The polyethylene has the formula (wherein n is 10 to 40). The concentration of the paraffin wax is preferably in the range of 1% by weight, more preferably 2% by weight, most preferably 3% by weight, and preferably up to 15% by weight, and even more preferably up to 10% by weight, based on the weight of the polymer particles. Examples of suitable commercially available paraffin waxes include Michem Emulsion 47950, Michem Lube 723, and Aquacer Emulsion 593, which are paraffin wax aqueous emulsions stabilized with a nonionic surfactant.

[0011] The composition may further contain a higher molecular weight (150 to 1500 repeating units) polyethylene (PE) or polypropylene (PP) wax. When the higher molecular weight PE or PP is used, its concentration is preferably in the range of 5 to 35% by weight, based on the weight of the paraffin wax and the higher molecular weight polyethylene or polypropylene wax. Examples of commercially available paraffin wax / PE blend emulsions include Mychem 62330 and Mychem 66035 paraffin wax / PE wax blend emulsions.

[0012] The composition typically has a median diameter mean (D) in the range of 1 μm to 50 μm. 50The composition further comprises filler particles having a particle size of . Examples of suitable fillers, also called fillers in the art, include calcium carbonate, silica, alumina, kaolin, clay, talc, graphite, mica, diatomaceous earth, glass powder, fibers or microspheres, aluminum hydroxide, perlite, barium sulfate, magnesium carbonate, calcium dihydrate, rock wool, wollastonite, zeolite, ceramic and thermoplastic microspheres, polymer fibers, and crosslinked rubber particles. The volume concentration (PVC) of the pigment in the composition is in the range of 40, preferably 50, and up to 70, preferably 65. PVC is calculated using the following formula:

[0013]

number

[0014] As the following examples illustrate, coatings resulting from the compositions of the present invention exhibit a significant reduction in water sensitivity, which is of particular interest in LASD applications.

[0015] M of polymer particles n Gel permeation chromatography method for measuring GPC samples were prepared in THF at a concentration of 5 mg / mL based on the polymer solid content. The sample solution was kept on a flatbed shaker at room temperature overnight, and then filtered through a 0.45 µm PTFE filter (Whatman filter paper) before GPC analysis. The GPC instrument consists of an Agilent 1200 series HPLC system (degasser, pump, autosampler) and a Wyatt T-rEX refractive index detector. Polymer separation was performed with one TOSOH TSK gel GMH xl -L and one TOSOH TSK gel G5000H xl column set consisting of columns (each packed with 9 µm styrene divinylbenzene gel, each having dimensions of 7.5 mm inner diameter × 30 cm), using THF as the mobile phase at a flow rate of 1 mL / min, and the injection volume was 40 µL.

[0016] Astra 7 software (manufactured by Wyatt Technology) was used for data acquisition and processing. M n and M w were calculated using a conventional calibration method based on polystyrene standards (manufactured by Agilent Technology), as shown in Table 1 below:

[0017]

Table 1

[0018] The number-average molecular weight and weight-average molecular weight were obtained by the following formula based on the polystyrene calibration curve and the sample elution profile:

[0019]

Formula

[0020] Coating formulations containing paraffin wax or a blend of paraffin wax and polyethylene were prepared in the order listed in Table 2. The components were mixed in a general-purpose stirrer for 10 minutes and then equilibrated overnight. The wax was added in an amount of 6.4% by weight based on the weight of the binder solids. A comparative example prepared without wax (Table 3) used the same formulation, but the wax solids were replaced with additional binder solids. The binder was approximately 21,000 g / mol M n This refers to latex with a 50.5% solid content, in the ratio of BA=55, MMA=42, and PEM=3. (PEM has 60% activity.) Density refers to dry density. TERGITOL, TAMOL, and ACRYSOL are trademarks of The Dow Chemical Company or its affiliates. Expansionl 031 WUF 40 refers to Expansionl 031 WUF 40 thermoplastic microspheres.

[0021] [Table 2]

[0022] [Table 3]

[0023] Water absorption test The coating was applied to an aluminum panel to obtain a 4 × 100 × 80 mm sample. The sample was then left at room temperature for 30 minutes, followed by firing at 150°C for 30 minutes. The sample was cooled to room temperature, weighed, and its total mass was determined. The sample was then immersed in 10 cm of water for 48 hours and weighed again. Water absorption was reported as a percentage of the mass difference between the immersed and unimmersed samples.

[0024] Table 4 shows the water absorption rate (%WPU, average value of 3 panels tested after 2 days) for coatings containing paraffin wax and coatings without paraffin wax. ML190 refers to Mychem Lube 190 polyethylene wax emulsion. Aquacer 593 refers to Aquacer 593 polypropylene wax emulsion. ML723 refers to Mychem Lube 723 paraffin wax emulsion. Aquacer 497 refers to Aquacer 497 paraffin wax emulsion. ME62330 refers to Mychem 62330 paraffin wax / PE wax blend emulsion, and ML270R refers to Mychem Lube 270R paraffin wax / PE wax blend emulsion.

[0025] Brookfield viscosity was measured at 25°C for coatings with viscosities of 1,000,000 to 10,000,000 centipoise (cP) using a Brookfield RV DV-I+ viscometer equipped with a Brookfield Helipath stand and a T-bar type TE spindle. Brookfield T-bar type TC and type TF spindles can be used for viscosities of 200,000 to 1,000,000 cP and 10,000,000 to 20,000,000 cP, respectively. The spindle rotation speed was 0.5 rpm, and the spindle was operated for 120 seconds (i.e., under non-shear conditions) before measurement was performed. The stand allows the spindle to descend and move within the coating during rotation, ensuring proper measurement of high-viscosity materials. Viscosity is expressed as centipoise (cP) × 10⁻⁶ 4 It is measured at [location]. Table 4 shows water absorption data for various coatings.

[0026] JPEG0007917524000007.jpg40170

[0027] The data show no difference in water absorption between coatings prepared from formulations containing PE wax (Comparative Example 2) and coatings prepared from formulations without wax (Comparative Example 1). In contrast, a substantial reduction in water absorption was observed in coatings prepared from formulations containing paraffin wax (Examples 1 and 2) and coatings prepared from formulations containing a blend of paraffin wax and polyethylene wax (Examples 3 and 4). Examples of the inventions of this application include the following: [1] z-average particle size in the range of 50 nm to 500 nm, and calculation T in the range of -25°C to 30°C g A composition comprising an aqueous dispersion of acrylic polymer particles having a value, paraffin wax, filler particles, and a rheology modifier, wherein the volume concentration of the pigment in the composition is in the range of 40 to 70, and the composition has a Brookfield viscosity in the range of 200,000 cP to 20,000,000 cP when not under shear conditions. [2] The composition according to [1], wherein the concentration of the acrylic polymer particles is in the range of 10 to 25% by weight based on the weight of the composition, and the concentration of the paraffin wax is in the range of 1 to 15% based on the weight of the acrylic polymer particles. [3] The acrylic polymer particles are calculated in the range of -10°C to 20°C. g The composition according to [2] above, having a value and comprising structural units of methyl methacrylate and one or more monomers selected from the group consisting of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and 2-propylheptyl acrylate, and having a Brookfield viscosity in the range of 1,000,000 cP to 10,000,000 cP. [4] The composition according to [3], wherein the acrylic polymer particles further comprise structural units of phosphoethyl methacrylate. [5] The composition according to [2] above, further comprising 150 to 1500 repeating units of polyethylene or polypropylene wax, wherein the weight-to-weight ratio of the polyethylene wax or polypropylene wax to the paraffin wax is in the range of 5 to 35% by weight, based on the weight of the paraffin wax and the polyethylene wax or polypropylene wax. [6] The composition according to [3], further comprising 150 to 1500 repeating units of polyethylene wax, wherein the weight-to-weight ratio of the polyethylene wax to the paraffin wax is in the range of 5 to 35% by weight, based on the weights of the paraffin wax and the polyethylene wax. [7] The composition according to [3] above, wherein the bulking agent particles are calcium carbonate particles. [8] The composition according to [1] above, comprising an opacity pigment of less than 5PVC level. [9] The composition according to [2] above, wherein the polymer particles have a number-average molecular weight in the range of 10,000 to 40,000 g / mol.

[10] The composition according to [1] above, further comprising potato starch.

Claims

1. The z-average particle size is in the range of 50 nm to 500 nm, and T is calculated by Fox's equation within the range of -25°C to 30°C. ｇ A composition comprising an aqueous dispersion of acrylic polymer particles having a value, paraffin wax, filler particles, a rheology modifier, and starch, The acrylic polymer particles comprise structural units from methyl methacrylate, ethylenically unsaturated acid monomers, and one or more monomers selected from the group consisting of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and 2-propylheptyl acrylate. The volume concentration (PVC) of the pigment in the above composition is in the range of 40% by volume to 70% by volume. The composition has a Brookfield viscosity in the range of 200,000 cP to 20,000,000 cP at 25°C when not under shear conditions. A composition in which the bulking agent particles are selected from the group consisting of calcium carbonate, silica, alumina, kaolin, clay, talc, graphite, mica, diatomaceous earth, glass powder, glass fibers, glass microspheres, aluminum hydroxide, perlite, barium sulfate, magnesium carbonate, calcium dihydrate, rock wool, wollastonite, zeolite, ceramic and thermoplastic microspheres, polymer fibers, and crosslinked rubber particles.

2. The composition according to claim 1, wherein the concentration of the acrylic polymer particles is in the range of 10 to 25% by weight based on the weight of the composition, and the concentration of the paraffin wax is in the range of 1 to 15% based on the weight of the acrylic polymer particles.

3. The acrylic polymer particles are in the range of -10°C to 20°C, and T is calculated by Fox's equation. ｇ It has a value and is composed of structural units of methyl methacrylate, butyl acrylate, and phosphoethyl methacrylate (PEM), The composition according to claim 2, wherein the composition has a Brookfield viscosity in the range of 1,000,000 cP to 10,000,000 cP at 25°C.

4. The composition according to claim 3, wherein the acrylic polymer particles contain 0.1 to 6% by weight of structural units of phosphoethyl methacrylate.

5. The composition according to claim 1, further comprising 150 to 1500 repeating units of polyethylene or polypropylene wax, wherein the weight-to-weight ratio of the polyethylene wax or polypropylene wax to the paraffin wax is in the range of 5 to 35% by weight, based on the weight of the paraffin wax and the polyethylene wax or polypropylene wax.

6. The composition according to claim 1, further comprising 150 to 1500 repeating units of polyethylene wax, wherein the weight-to-weight ratio of the polyethylene wax to the paraffin wax is in the range of 5 to 35% by weight, based on the weights of the paraffin wax and the polyethylene wax.

7. The composition according to claim 1, wherein the bulking agent particles are calcium carbonate particles.

8. The composition according to claim 1, comprising an opacity pigment of less than 5 PVC level.

9. The composition according to claim 2, wherein the polymer particles have a number-average molecular weight in the range of 10,000 to 40,000 g / mol.

10. The composition according to claim 1, wherein the starch is potato starch.

11. A composition comprising an aqueous dispersion of acrylic polymer particles having a z-average particle size in the range of 50 nm to 500 nm and a Tg value calculated by Fox's equation in the range of -25°C to 30°C, paraffin wax, filler particles, a rheology modifier, and potato starch, The acrylic polymer particles are composed of structural units of methyl methacrylate, butyl acrylate, and phosphoethyl methacrylate (PEM), and contain 0.1 to 6% by weight of the phosphoethyl methacrylate structural unit. The volume concentration (PVC) of the pigment in the above composition is in the range of 40% by volume to 70% by volume. The composition has a Brookfield viscosity in the range of 200,000 cP to 20,000,000 cP at 25°C when not under shear conditions. The aforementioned bulking agent particles are calcium carbonate particles. A composition for liquid-applied acoustic attenuation coatings.

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