Aqueous acoustic damping composition and articles and components thereof

Abstract

The present invention relates to an aqueous acoustic damping composition comprising an acrylic polymer, at least one filler, starch, an impact modifier and a rosin ester wherein the impact modifier is an ester-based impact modifier. The aqueous acoustic damping composition may be used as an acoustic damping coating (e.g., in aqueous liquid applied acoustic damping applications in the automotive industry) that provides very good impact resistance at low temperatures (less than-20 DEG C) while providing good acoustic performance.

Description

Technical Field

[0001] This disclosure relates to aqueous acoustic damping compositions, articles thereof, and components for use in motor vehicles, and particularly to aqueous acoustic damping compositions exhibiting good shock resistance at low temperatures. These aqueous acoustic damping compositions can be used, for example, in automotive industry applications. Background Technology

[0002] Sound damping materials, such as manually applied sound-absorbing patches using asphalt pads, have helped suppress noise caused by vibration in various industrial equipment and vehicles. To save labor during installation and replacement, sprayable polymer-based sound damping compositions (also known as liquid-applied acoustic damping (LASD) materials) have been developed accordingly. LASD offers higher damping efficiency and a better odor, provides a reduced application amount, and facilitates easy application via an automatically controlled application gun, making it more suitable for automated, lightweight, and environmentally friendly designs.

[0003] LASD compositions can be characterized by either aqueous or non-aqueous systems. Compared to non-aqueous LASD coatings, aqueous systems offer undeniable advantages (such as easier design, a wider damping range, lower VOC emissions, and lower cost). However, their drying performance under bake- or air-drying conditions typically has a narrow temperature window and often results in large blister formation and cracking. Furthermore, the adhesion of waterborne LASD coatings is greatly affected by the target surface.

[0004] With the increasing demand for new energy vehicles, the demand for LASD in this sector is expected to grow rapidly. However, OEMs have raised the bar for testing, as vehicle applications require LASDs to be reliable in variable environments, such as low temperatures and high humidity. The damping performance of LASD materials largely depends on the glass transition temperature of the incorporated polymer latex resin. T g Therefore, the polymer's T g Typically, this ranges from approximately room temperature (-2°C to 25°C). Therefore, polymers become brittle at lower temperatures (e.g., -10°C to -30°C, or -20°C to -30°C), causing LASD to form deep cracks or even detach from the substrate in response to impacts at such low temperatures. While adding conventional plasticizers can reduce the polymer's... T gThis provides better shock resistance at low temperatures, but the acoustic performance of the final product is usually compromised accordingly. Therefore, there is a need to develop waterborne LASD compositions that possess both good acoustic performance and good shock resistance at low temperatures. Summary of the Invention

[0005] Therefore, the object of the present invention is to overcome the above-mentioned disadvantages by providing an aqueous LASD composition that has good shock resistance at low temperatures (equal to or less than -20°C) and good acoustic and vibration damping properties at ambient temperatures (-10°C to 60°C).

[0006] An unexpected discovery has been made of waterborne acoustic damping compositions prepared from curable waterborne compositions, comprising at least: an acrylic polymer; at least one filler; starch; an ester-based impact retardant; and rosin ester, wherein the waterborne acoustic damping compositions provide a very good balance between damping performance and impact resistance at low temperatures.

[0007] According to one aspect, the present invention relates to a curable damping coating composition comprising: a) an acrylic polymer, b) at least one filler, c) starch, d) an impact retardant, and e) a rosin ester, wherein the impact retardant is an ester-based impact retardant.

[0008] According to one aspect, the present invention relates to a damping coating comprising a cured product of an aqueous acoustic damping composition according to the present invention.

[0009] According to another aspect, the present invention also relates to an article comprising a substrate, a damping coating disposed on the substrate, and a second substrate, wherein the damping coating is a cured product of an aqueous acoustic damping composition according to the present invention.

[0010] According to another aspect, the present invention also relates to automotive panels including articles of the present invention. Attached Figure Description

[0011] Figure 1 The damping coefficient measurement results for E5, CE5, CE8, and CE9 are shown. Detailed Implementation

[0012] The invention will be described in more detail in the following paragraphs. Unless explicitly stated otherwise, each aspect thus described may be combined with one or more other aspects. In particular, any feature indicated as preferred or advantageous may be combined with one or more other features indicated as preferred or advantageous.

[0013] In the context of this invention, unless the context otherwise requires, the terminology used will be interpreted according to the following definitions.

[0014] Unless the context clearly specifies otherwise, the singular forms “a / an” and “the” as used herein include both the singular and plural references. For example, references to “filler” cover embodiments having one, two, or more fillers. Unless the content clearly specifies otherwise, the term “or” as used in this specification and the appended claims is generally used in its meaning including “and / or”.

[0015] As used herein, the term “comprising / comprises / comprised of” is synonymous with “including / includes” or “containing / contains”, and is inclusive or open-ended, and does not exclude additional undescribed members, elements, or method steps.

[0016] The term "ambient temperature" refers to the temperature range of -10°C to 60°C (inclusive).

[0017] The term "low temperature" refers to a temperature in the range of -20°C or less, preferably in the range of -30°C to -20°C (inclusive).

[0018] The definition of numerical endpoints includes all numbers and fractions falling into their respective ranges, as well as the listed endpoints.

[0019] Unless otherwise defined, all terms used in this disclosure (including technical and scientific terms) have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains. Further guidance includes terminology definitions to better understand the teachings of this invention.

[0020] In the context of this disclosure, several terms will be used.

[0021] The term "polymer" as used in this article is consistent with its common usage in chemistry. A polymer is composed of many repeating subunits. The term "polymer" is used to describe the material obtained from a polymerization reaction.

[0022] The term "acrylic acid" refers to either or both of "acrylic acid" and "methacrylic acid".

[0023] The term "acrylate" refers to either or both of "acrylate" and "methacrylate".

[0024] The term "alkyl" refers to a monovalent group that is a residue of an alkane, including straight-chain, branched, cyclic, and bicyclic alkyl groups, and combinations thereof (including both unsubstituted and substituted alkyl groups). Unless otherwise specified, alkyl groups typically contain 1 to 20 carbon atoms. In some embodiments, alkyl groups contain 1 to 15 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, 1 to 4 carbon atoms, or 1 to 3 carbon atoms. Examples of "alkyl" include, but are not limited to, methyl, ethyl, n-propyl, n-butyl, n-pentyl, isobutyl, tert-butyl, isopropyl, n-octyl, n-heptyl, ethylhexyl, cyclopentyl, cyclohexyl, octadecyl, benzyl, adamantyl, norbornyl, etc.

[0025] As used herein, the term "curing" refers to the hardening process of a material. This term is intended to encompass drying the material by evaporating water and a co-solvent from it, as well as crosslinking (where applicable) of components within the material that have reactive groups.

[0026] For the purposes of this invention, weight-average molecular weight ( M w The determination was performed using gel permeation chromatography based on polystyrene standards.

[0027] The viscosity of the composition can be determined using a Brookfield viscometer (Model RVT) under standard conditions of 25°C and 50% relative humidity (RH). The viscometer is calibrated using silicone oil of known viscosity, ranging from 5000 cps to 300000 cps. A set of RV rotors connected to the viscometer is used for calibration. Measurements of the damped composition are performed at 25°C using a No. 7 rotor at 20 rpm for 1 minute until the viscometer is balanced.

[0028] As used herein, the term "softening point" refers to the temperature at which a material (such as a polymer) loses its solid characteristics and becomes relatively fluid. The softening points of the materials given herein are temperatures measured using the standard ball-ring method according to ASTM E28.

[0029] The glass transition temperature used in this article ( T g The value was determined by differential scanning calorimetry (DSC) according to DIN 53 765 using a ramp rate of 20 K / min and a midpoint measurement.

[0030] As previously described, embodiments of this disclosure relate to an aqueous acoustic damping composition comprising at least: an acrylic polymer; at least one filler; starch; an ester-based impact modifier; and rosin ester. The aqueous acoustic damping composition further comprises a surfactant, and / or a thickener, and / or expandable microspheres, and / or a coalescing agent, and / or a colorant, and / or a biocide, and / or an antifoaming agent. Furthermore, the liquid phase of the aqueous acoustic damping composition comprises water.

[0031] acrylic polymers The acrylic polymers suitable for use in this invention are in dispersed (emulsified) form and can be selected from any of the acrylic polymer materials conventionally used in aqueous compositions capable of forming vibrational and / or damping coatings on a substrate surface. Preferred acrylic polymers include dispersions of acrylate polymers and copolymers (sometimes referred to in the art as acrylic resins), such as copolymers of lower alkyl esters of (meth)acrylate (e.g., n-butyl acrylate) with comonomers (e.g., styrene and / or acrylonitrile). Mixtures of the aforementioned polymers can be used, and combinations are preferred for obtaining the desired properties in the ultimately cured coating. For example, different polymers with different glass transition temperature characteristics can be used in combination. Generally, the glass transition temperatures of the polymers used in this invention typically range from about -10°C to about 40°C, preferably from 0°C to 20°C. However, in one embodiment of the invention, a combination of polymers is used, wherein one polymer has a glass transition temperature greater than 0°C (e.g., 5°C to 35°C). T g The other polymer is an elastomer and has a temperature range of less than 0°C (e.g., -10°C to -30°C). T g Both polymers can be, for example, acrylic resins with different monomer compositions, which are selected to provide the desired effect. T g feature.

[0032] According to the present invention, the aqueous dispersion of the acrylic polymer is typically obtained with a solids content of more than 45% by weight, preferably more than 50% by weight. In some embodiments of the present invention, the amount of the acrylic polymer in the composition is 5 to 20 parts by weight, or 5 to 15 parts by weight, or 5 to 11 parts by weight, or 7 to 10 parts by weight.

[0033] filler This invention comprises one or more inorganic fillers in particulate form, which are incorporated into an aqueous composition to provide a matrix for a dry coating, adjust the hardness of the dry coating, improve the sound or vibration damping properties of the dry coating, control bubbling of the dry coating, and / or modify the flammability of the dry coating, and for other purposes. The one or more inorganic fillers may be in any suitable form (e.g., powder, fibrous, needle-like, flake-like, spherical, plate-like, and other shapes known in the art) and should be insoluble in water. The surface of the filler may be coated with hydrophilic / hydrophobic small molecules / polymers or left unmodified. Examples of suitable inorganic fillers include, but are not limited to: calcium carbonate, silica, alumina, clay, talc, mica, diatomaceous earth, glass powder or fibers, aluminum hydroxide, perlite, barium sulfate, magnesium carbonate, calcium dihydrate, rock wool, asbestos, wollastonite, zeolite, glass or ceramic microspheres, graphite, etc., and mixtures thereof. Preferred inorganic fillers include calcium carbonate, silica, and alumina.

[0034] The inorganic filler is characterized by an average particle size (d50) of 10 to 100 μm and a d95 of 20 to 200 μm.

[0035] The amount of inorganic filler in the composition is particularly at least 55 parts by weight, or at least 60 parts by weight, or at least 62 parts by weight, or at least 65 parts by weight, or at least 70 parts by weight, or at least 75 parts by weight of the particulate filler in the composition.

[0036] starch When the damping composition coating is baked and dried, the drying control agent minimizes the occurrence of cracks and blistering in the coating. The use of cellulose- or starch-based polysaccharide drying control agents is desirable, with partially water-insoluble starch being particularly preferred. Modified cellulose or starch with partial solubility in water (e.g., cellulose phosphate) can also be used. Under certain conditions, it may be advantageous to include up to 3.5 parts by weight or up to 5.0 parts by weight of starch in the composition, representing the damping composition.

[0037] Ester-based impact modifiers The ester-based impact inhibitors suitable for use in this invention include ester compounds represented by the following formula:

[0038] Among them, independently, R1, R2, R3, and R4 each independently represent H or R5 represents a straight-chain or branched alkyl group having 1 to 18 carbons, preferably 1 to 4 carbons. More preferably, R5 represents at least one of n-propyl, isopropyl, n-butyl, and isobutyl. R1 and R2 cannot both be H.

[0039] In some embodiments of the invention, the amount of the ester-based impact inhibitor in the composition is from 0.3 parts by weight to 6.0 parts by weight, preferably from 0.4 parts by weight to 5.0 parts by weight of the composition.

[0040] Rosin ester The compositions of the present invention optionally comprise rosin esters. As used herein, rosin esters refer to chemicals having the following general formula: XC(=O)-OR, in: X is rosin or a rosin derivative; and R represents any organic group.

[0041] The "rosin" portion of rosin esters is or is derived from the standard material commercially known as rosin. Rosin is primarily composed of tricyclic fused-ring carbonyl groups. 20 A mixture of monocarboxylic acids: Although pinoic acid and rosin acid are the main acids, rosin also contains C-containing acids. 20 Any one or more isomers of cyclic carboxylic acids are suitable as the rosin moiety of rosin esters.

[0042] In various preferred expressions (which are not intended to be mutually exclusive with molecular weight conditions), the softening point of each of the rosin esters present in the preferred compositions herein is 40°C to 130°C, preferably 50°C to 110°C, and more preferably 50°C to 90°C. It can be noted that glycerides and pentaerythritol esters of rosin, wood rosin, and tall oil rosin are particularly preferred.

[0043] In some embodiments of the present invention, the amount of rosin ester in the composition is from 0.5 parts by weight to 5.0 parts by weight, or from 1.0 parts by weight to 3.0 parts by weight, or from 1.0 parts by weight to 2.5 parts by weight of the composition.

[0044] Optional additives The compositions of the present invention will generally also contain optional additives, which must be minor components but can still impart improved properties to the compositions. The total amount of optional additives in the composition will preferably be at most 10 parts by weight, more preferably 0.1 to 10 parts by weight or 0.1 to 7.5 parts by weight of the composition. The desired viscosity of the composition will generally determine the total amount of optional additives added.

[0045] Such additives include: cosolvents; thickeners; drying control agents; surfactants, such as sodium hexametaphosphate, sodium tripolyphosphate, or polymeric surfactants polycarboxylic acids; defoamers; and foaming agents. The aqueous coating composition of the present invention contains a certain amount of expandable microspheres, which effectively improve the surface appearance of the coating formed by heating and drying the composition, and / or improve the sound or vibration damping properties of the coating. Expandable microspheres are well known to those skilled in the art and typically comprise small-diameter polymer shells or bubbles encapsulating one or more volatile substances (such as light hydrocarbons and halogenated hydrocarbons). Suitable expandable microspheres are also available from commercial sources (such as products sold by Casco Nobel AB or Akzo Nobel under the trademark "EXPANCEL"). The average particle size of the microspheres and the temperature at which the microspheres begin to expand are not considered particularly critical. However, generally, the microspheres will have a weight-average particle size in the range of about 5 to about 50 micrometers and an expansion initiation temperature in the range of about 70°C to about 160°C (T0). 开始 (As measured by thermomechanical analysis). A mixture of different expandable microspheres with different average particle sizes and / or different expansion properties can be used.

[0046] Preparation method of water-based acoustic damping composition Aqueous acoustic damping compositions are formulated by simply mixing various components. While there is no intention to restrict the order in which the components are mixed, it is prudent to first form an aqueous dispersion of the acrylic copolymer and an aqueous dispersion of the individual rosin ester component, and then mix said dispersion with the other components. In this case, the aqueous dispersion of the rosin ester can, for example, have a solids content of 45 to 70% by weight.

[0047] In some embodiments, the aqueous acoustic damping composition comprises 5.0 to 30.0 parts by weight of water as a liquid phase.

[0048] If necessary, the composition can be prepared well before its application. However, in an interesting alternative embodiment, a concentrated composition can be obtained first by mixing the components with only a portion of the water present in the applied composition; the concentrated composition can then be diluted with the remaining water shortly before its application. It is thought that such concentrated compositions can be prepared and stored as single-package concentrates or multi-component concentrates, which can be converted simply by dilution with water, while two or more of the multi-component concentrates must be combined and diluted to form the complete working composition according to the invention. Any dilution can be achieved simply by adding water (particularly deionized water and / or demineralized water) during mixing. The composition can also be prepared in a flushing stream, thereby injecting one or more concentrated streams into a continuous water stream.

[0049] Where there is no particular intention to limit the amount of water contained in the aqueous composition, the composition preferably contains 5 to 20% by weight, preferably 5 to 15% by weight, of water based on the weight of the composition. In alternative but not mutually exclusive descriptions of properties, the composition may be defined by a viscosity of 10 to 300 Pa·s (e.g., 50 to 200 Pa·s) as measured using a Brookfield viscometer at 25°C.

[0050] According to the broadest aspect of the invention, the above composition is applied to a substrate and then cured in situ.

[0051] The invention is not intended to limit the substrates to which the compositions can be applied. In applications to vehicle panels, exemplary substrates may be metallic, polymeric, or combinations thereof. However, specific references may be made to: ferrous metals, such as iron, steel, and their alloys; non-ferrous metals, such as aluminum, zinc, and their alloys; and combinations thereof. In illustrative embodiments, the substrate may be formed of: cold-rolled steel; electro-galvanized steel, such as hot-dip galvanized steel or electro-galvanized iron-zinc steel; or aluminum.

[0052] Pretreatment of the relevant surfaces to remove foreign matter is generally recommended before applying the composition; if applicable, this step can promote the subsequent adhesion of the composition to them. Such treatments are known in the art and can be performed in a single-stage or multi-stage manner, consisting of, for example, one or more of the following: immersion in an aqueous alkaline degreasing bath; treatment with an aqueous cleaning emulsion; treatment with a cleaning solvent (such as carbon tetrachloride or trichloroethylene); and rinsing with water, preferably with deionized or demineralized water. In those cases where an aqueous alkaline degreasing bath is used, any degreasing agent remaining on the surface should be expected to be removed by rinsing the substrate surface with deionized or demineralized water.

[0053] The composition is then applied to a preferably pretreated, optionally primer-coated surface of a substrate by conventional application methods such as brushing; roller coating; doctor blade application; printing; and spraying, including but not limited to air atomization spraying, air-assisted spraying, airless spraying, and high-volume low-pressure spraying.

[0054] The thickness of the coating applied in this invention can be adjusted so that the final cured coating effectively suppresses noise and vibration transmission to the desired level. In many cases, the composition is applied as a wet film thickness of 1 to 5 mm. Applying thinner layers within this range is more cost-effective and offers the possibility of reducing harmful thick cured areas. However, strict control must be exercised when applying thinner coatings or layers to avoid the formation of discontinuous cured films.

[0055] The curing of the compositions of the present invention is generally carried out at temperatures ranging from 80°C to 200°C, preferably from 90°C to 180°C. A suitable temperature depends on the specific compound present and the desired curing rate, and can be determined in each case by those skilled in the art using simple preliminary tests (if necessary).

[0056] List of Implementation Plans 1. An aqueous acoustic damping composition, said aqueous acoustic damping composition comprising: a) Acrylic polymers, b) At least one filler, c) Starch, d) Impact-resistant agent, and e) Rosin esters, The impact-resistant agent mentioned above is an ester-based impact-resistant agent.

[0057] 2. The aqueous acoustic damping composition according to embodiment 1, wherein the impact-resistant agent comprises an ester compound represented by the following formula:

[0058] Independently, R1, R2, R3, and R4 each independently represent H or R5 indicates a straight-chain or branched alkyl group having 1 to 18 carbon atoms.

[0059] 3. The aqueous acoustic damping composition according to any one of the foregoing embodiments, wherein R5 represents a straight-chain or branched alkyl group preferably having 1 to 4 carbon atoms.

[0060] 4. The aqueous acoustic damping composition according to any one of the foregoing embodiments, wherein R5 represents n-propyl, isopropyl, n-butyl, and isobutyl.

[0061] 5. The aqueous acoustic damping composition according to any one of the foregoing embodiments, wherein the aqueous acoustic damping composition comprises 0.3 to 6.0 parts by weight of an anti-impact agent.

[0062] 6. The aqueous acoustic damping composition according to any one of the foregoing embodiments, wherein the aqueous acoustic damping composition comprises 0.4 to 5.0 parts by weight of an impact-resistant agent.

[0063] 7. The aqueous acoustic damping composition according to any one of the foregoing embodiments, wherein the softening point of the rosin ester is 50°C to 130°C, preferably 60°C to 120°C, and more preferably 70°C to 110°C.

[0064] 8. The aqueous acoustic damping composition according to any one of the foregoing embodiments, wherein the aqueous acoustic damping composition comprises 1.0 to 3.0 parts by weight of rosin ester.

[0065] 9. The aqueous acoustic damping composition according to any one of the foregoing embodiments, wherein, based on the total acrylic polymer, the acrylic polymer comprises 10 to 50% by weight of a styrene-based monomer.

[0066] 10. The aqueous acoustic damping composition according to any one of the foregoing embodiments, wherein the aqueous acoustic damping composition further comprises 0.1 to 1.0 parts by weight of a thickener and / or 0.1 to 0.5 parts by weight of expandable microspheres.

[0067] 11. The aqueous acoustic damping composition according to any one of the foregoing embodiments, wherein, based on the total weight of the aqueous acoustic damping composition, it comprises: a) 5.0 to 15.0 parts by weight of the acrylic polymer, b) 55.0 to 75.0 parts by weight of the said filler, c) 1.0 to 5.0 parts by weight of the starch, d) 0.3 to 6.0 parts by weight of the aforementioned impact-resistant agent, and e) 0.5 to 5.0 parts by weight of the rosin ester.

[0068] 12. The aqueous acoustic damping composition according to any one of the foregoing embodiments, wherein the aqueous acoustic damping composition comprises 5.0 to 30.0 parts by weight of water as a liquid phase.

[0069] 13. A damping coating comprising a cured product of the aqueous acoustic damping composition according to any one of claims 1-12.

[0070] 14. The damping coating according to embodiment 13, wherein, in a temperature range of 20°C to 30°C, the loss factor of the damping composition is equal to or greater than 0.12, or preferably equal to or greater than 0.13, or preferably equal to or greater than 0.15.

[0071] 15. An article comprising a substrate, a damping coating disposed on the substrate, and a second substrate, wherein the damping coating is a cured product of an aqueous acoustic damping composition according to any one of embodiments 1-12.

[0072] 16. An automotive panel, the automotive panel comprising the article of manufacture according to embodiment 15.

[0073] Example The invention will be further described and illustrated in detail below with reference to the embodiments. These embodiments are intended to help those skilled in the art better understand and practice the invention, but are not intended to limit the scope of the invention. Unless otherwise stated, all figures in the embodiments are based on weight.

[0074] raw material

[0075] All raw materials are used directly without any special processing.

[0076] Example 1 <Preparation of Aqueous Sound Damping Composition> The compositions of the present invention comprise the following raw materials in the indicated amounts. The composition is obtained by first adding the liquid material to a container and mixing at 5°C to 25°C. Then, a powdered filler material is added, and mixing continues until a well-mixed, homogeneous paste is obtained. Then, a rheology modifier and water are added during mixing to adjust the desired viscosity. Vacuum is preferably used during mixing to reduce trapped air bubbles.

[0077] <Cure of Aqueous Sound Damping Composition> Apply the composition to the substrate by hand brushing. Control the thickness to about 1 mm to about 5 mm (e.g., about 2 mm to about 4 mm). After application to the substrate, the composition is typically baked for at least about 10 minutes, more typically about 15 to about 30 minutes. For E1 to E7 and CE1 to CE10, the composition is cured at about 150°C for 20 minutes.

[0078] Examples 2-7 and CE1-CE10 Aqueous acoustic damping compositions of E2 to E7 and CE1 to CE10 were prepared according to Example 1. The aqueous acoustic damping compositions of E2 to E7 and CE1 to CE10 were cured according to Example 1. Further details are listed in the results section below.

[0079] Test methods <Damping Coefficient Test> Damping tests were performed on the water-based damping coatings prepared in the selected examples and comparative examples using the TWS Michael Schulthes obster testing system. The specific damping test method was performed according to GB / T 18258-2000. The steel plate dimensions were 240 mm × 10 mm × 1 mm. The water-based damping coating dimensions were 216 mm × 10 mm × 3.0 mm, and it was baked under standard curing conditions. Before testing, the samples were placed at room temperature for at least 24 hours. Damping coefficient tests were conducted at a temperature range of -40°C to 60°C, and measurements were performed every 2.5°C when the temperature stabilized. The composite loss factor was recorded at a frequency of 200 Hz and measured using 3 kg / cm². 3 The surface density is normalized. Table 1 shows the measurement results of the damping coefficient.

[0080] Record the damping coefficient results and evaluate them as shown below: - Unacceptable: Loss factor is less than 0.12 within the temperature range of 20℃ to 30℃; - Qualified: Within a temperature range of 20℃ to 30℃, the loss factor is equal to or greater than 0.12.

[0081] <Open Time Test> The composition was first applied to the substrate by manual brushing. The sample size was 12 cm. The sample was 8 cm long and 3.5 mm thick. It was placed at 25°C and 50% RH for 24 hours, and then cured at 150°C for 20 minutes.

[0082] Record the results of the opening hours test and evaluate them as follows: - Unacceptable: After baking, the bubble size is greater than 20 mm; or, after baking, the sag is equal to or greater than 2 mm. - Acceptable: After baking, the bubble size is equal to or greater than 5 mm and equal to or less than 20 mm; or the surface crack size is equal to or greater than 20 mm. - Excellent: After baking, there are no bubbles, or the bubble size is less than 5 mm; and the surface crack size is less than 20 mm.

[0083] <Cold drop test> The composition was first applied to the substrate by manual brushing. The applied coating was 16 cm in size. The sample was 7 cm long and 2 mm thick. It was placed at 25°C and 50% RH for 10 minutes, then cured at 150°C for 20 minutes. The sample was then cooled at 25°C and 50% RH for 24 hours and placed in a -30°C cold chamber for 2 hours. Immediately after removing the patternplate from the cold chamber, a low-temperature drop test was performed. A steel ball (40 mm in diameter, approximately 250 g in weight) from a height of 400 mm was dropped onto the back of the substrate.

[0084] Record the results of the low-temperature drop test and evaluate them as follows: - Unacceptable: The sample is broken or has deep cracks extending down to the substrate; - Pass: The sample remains intact, or only surface cracks are formed on the sample surface.

[0085] Table 1

[0086] Table 1 shows the aqueous acoustic damping compositions for E1-E7.

[0087] Table 2

[0088] Table 2 shows the test results of the aqueous acoustic damping compositions E1-E7.

[0089] In Examples 1-7, aqueous acoustic damping compositions were prepared according to formulations provided by the present invention. These formulations particularly comprise acrylic polymers, fillers, starch, impact modifiers, and rosin esters. It can be seen that when the content of the components claimed by the present invention is within a certain range, the impact modifier synergistically works with the rosin ester, enabling the prepared aqueous acoustic damping composition to simultaneously possess good acoustic performance and good impact resistance at the required low temperature (indicated by the results of low-temperature drop tests). As can be seen from E7, to simultaneously ensure good acoustic performance and good impact resistance, the aqueous acoustic damping composition contains at least 0.44 parts by weight of a suitable impact modifier. E1 to E6 indicate that acoustic performance improves with increasing impact modifier content.

[0090] Table 3

[0091] Table 3 shows the aqueous acoustic damping compositions of CE1-CE10.

[0092] Table 4

[0093] Table 4 shows the test results of the aqueous acoustic damping compositions CE1-CE10.

[0094] In Comparative Examples 1-4, aqueous acoustic damping compositions were prepared without an impact-resistant agent. The cured aqueous acoustic damping compositions failed the low-temperature drop test and therefore did not exhibit good impact resistance at low temperatures. In Comparative Example 5, an aqueous acoustic damping composition was prepared without rosin ester. The cured aqueous acoustic damping composition also did not exhibit the expected impact resistance at low temperatures. In Comparative Example 6, the amount of impact-resistant agent was higher than expected. It can be seen that excessive impact-resistant agent has a negative impact on the open time. Although this sample passed the low-temperature drop test, it failed the damping test due to expansion. In Comparative Example 7, the amount of impact-resistant agent was less than expected, and this aqueous acoustic damping composition with insufficient impact-resistant agent failed the low-temperature drop test.

[0095] Figure 1 The damping coefficient measurement results for E5, CE5, CE8, and CE9 are shown.

[0096] The aqueous acoustic damping composition focuses on properties such as good acoustic performance at low temperatures (e.g., -30°C) and good shock resistance.

[0097] The damping coefficient measurements for E5 and CE5 show that the presence of rosin ester contributes to the peak of the loss factor and increases the loss factor value to greater than 1.2 in the temperature range of 20℃ to 30℃.

[0098] In comparative examples CE8 and CE9, the aqueous acoustic damping compositions contained no impact-resistant agents but rather conventional plasticizers (such as DOA or DINP). Furthermore, CE8, CE9, and E5 all contained the same acrylic emulsion as the main polymer. Comparing the test results of E5 and CE8 / CE9, the aqueous acoustic damping composition without impact-resistant agents exhibited a loss factor of less than 0.12 in the temperature range of 20°C to 30°C. Conventional plasticizers, acting as small-molecule plasticizers (such as the ester compounds DOA and DINP), can increase the flexibility of the aqueous acoustic damping composition, thus allowing the sample to pass the low-temperature drop test. However, conventional plasticizers shift the peak loss factor of the polymer composition to a lower temperature range, negatively impacting acoustic damping performance. Without impact-resistant agents, the damping test was not passed.

[0099] In this invention, it was unexpectedly discovered that an aqueous acoustic damping composition containing both an ester-based impact modifier and a rosin ester exhibits both good acoustic properties and good impact resistance at low temperatures.

Claims

1. An aqueous sound damping composition comprising: a) an acrylic polymer, b) at least one filler, c) a starch, d) an impact resistant agent, and e) a rosin ester, wherein the impact resistant agent is an ester-based impact resistant agent.

2. The aqueous sound damping composition according to claim 1, wherein the impact resistant agent comprises an ester compound represented by the following formula: wherein Independently, R1, R2, R3and R4each independently represent H or and R5represents a linear or branched alkyl group having 1 to 18 carbons.

3. The aqueous sound damping composition according to claim 2, wherein R5represents a linear or branched alkyl group preferably having 1 to 4 carbons.

4. The aqueous sound damping composition according to claim 2, wherein R5represents n-propyl, i-propyl, n-butyl and i-butyl.

5. The aqueous sound damping composition according to claim 1, wherein the aqueous sound damping composition comprises 0.3 to 6.0 parts by weight of the impact resistant agent.

6. The aqueous sound damping composition according to claim 1, wherein the aqueous sound damping composition comprises 0.4 to 5.0 parts by weight of the impact resistant agent.

7. The aqueous sound damping composition according to claim 1, wherein the rosin ester has a softening point of 50°C to 130°C, preferably 60°C to 120°C, more preferably 70°C to 110°C.

8. The aqueous sound damping composition according to claim 1, wherein the aqueous sound damping composition comprises 0.5 to 5.0 parts by weight of the rosin ester.

9. The aqueous acoustic damping composition of claim 1, wherein, The acrylic polymer comprises 10 to 50% by weight of styrene-based monomers based on the total acrylic polymer.

10. The aqueous sound damping composition according to claim 1, wherein the aqueous sound damping composition further comprises 0.1 to 1.0 parts by weight of a thickening agent, and / or 0.1 to 0.5 parts by weight of expandable microspheres.

11. The aqueous acoustic damping composition of claim 1, wherein, comprises, based on the total weight of the aqueous sound damping composition: a) 5.0 to 15.0 parts by weight of the acrylic polymer, b) 55.0 to 75.0 parts by weight of the filler, c) 1.0 to 5.0 parts by weight of the starch, d) 0.3 to 6.0 parts by weight of the impact resistant agent, and e) 0.5 to 5.0 parts by weight of the rosin ester.

12. The aqueous sound damping composition according to claim 1, wherein the aqueous sound damping composition comprises 5.0 to 30.0 parts by weight of water as a liquid phase.

13. A damping coating comprising a cured product of the aqueous sound damping composition according to any one of claims 1-12.

14. The damping coating of claim 13, wherein, The damping composition has a loss factor equal to or greater than 0.12 in a temperature range of 20°C to 30°C.

15. An article comprising a substrate, and a damping coating disposed on the substrate, and a second substrate, wherein the damping coating is a cured product of the aqueous sound damping composition according to any one of claims 1-12.

16. An automotive panel comprising the article according to claim 15.

Images