JP7833898B2 - Composition for sound absorbing materials - Google Patents

Description

This invention relates to a sound-absorbing material composition. The sound-absorbing material composition of this invention can be used particularly for vehicles.

Vibration damping materials are used to prevent vibration and noise in various structures and maintain quietness. For example, they are used under the floor of automobiles, as well as in railway vehicles, ships, aircraft, electrical equipment, building structures, and construction equipment. Conventionally, molded products such as plate-shaped or sheet-shaped molded products made from materials with vibration absorption properties have been used as materials for such vibration damping materials. However, as an alternative to molded products, coating-type vibration damping material formulations (paints) have been developed, and various vibration-damping coatings have been proposed that are formed by spraying them onto the relevant area or by applying them by any method.
For example, Patent Document 1 describes a vibration-damping coating film formed on a substrate, wherein the coating film has an average thickness of 1 mm or less, and consists of a lower layer on the substrate side and an upper layer, the upper layer containing an acrylic resin, zinc oxide, and calcium carbonate, and it is stated that it can exhibit excellent vibration damping properties despite being a thin film.

Japanese Patent Publication No. 2021-160210

In recent years, development has shifted from gasoline-powered vehicles to electric vehicles from an environmental protection perspective. While electric vehicles have the advantage of reduced engine noise and other noises compared to gasoline vehicles, it has been found that this also leads to a problem where high-frequency sounds that were not noticeable in gasoline vehicles become more prominent, increasing discomfort while driving.
The present inventors investigated a sound-absorbing material composition that exhibits excellent sound absorption properties, particularly in absorbing high-frequency sounds in the range of 3000 Hz to 5000 Hz.

In view of the above-mentioned problems, the inventors conducted research and discovered that a composition containing a compound having a sulfosuccinic acid (salt) skeleton exhibits excellent sound absorption in the high-frequency range, thus completing the present invention.

According to the present invention, a sound-absorbing material composition is provided that exhibits excellent sound absorption properties, particularly in absorbing high-frequency sounds in the range of 3000 Hz to 5000 Hz.

<Resin composition for sound absorbing material>
The sound-absorbing compositions of this disclosure include compounds having a sulfosuccinic acid (salt) skeleton.
A sulfosuccinic acid (salt) skeleton refers to a skeleton in which a sulfonic acid (salt) group is bonded to at least one carbon atom in the -C-C- portion of a skeleton represented as -CO-C-C-COOR (where R represents a hydrogen atom, alkyl group, metal salt, ammonium salt, or organic amine salt).
The alkyl group in R is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 5 to 10 carbon atoms, with a 2-ethylhexyl group being particularly preferred. Examples of metal atoms that form the metal salt in R include monovalent metal atoms such as alkali metal atoms such as lithium, sodium, and potassium; divalent metal atoms such as calcium and magnesium; and trivalent metal atoms such as aluminum and iron. Examples of organic amine salts in R include alkanolamine salts such as ethanolamine salt, diethanolamine salt, and triethanolamine salt, and triethylamine salt.
The above R is preferably a hydrogen atom, an alkyl group, or a metal atom, more preferably an alkyl group or a metal atom, and even more preferably a metal atom. As for the metal atom, the above monovalent metal atom is even more preferred, and sodium is particularly preferred.
In this disclosure, the term "sulfonic acid (salt) group" means a sulfonic acid group and/or a sulfonic acid base. Examples of the sulfonic acid base include metal salts, ammonium salts, organic amine salts, and mixed salts thereof of sulfonic acid groups.
Examples of metal atoms forming the metal salt of this disclosure and the organic amine salt are the same as those described above.
From the viewpoint of enabling the resulting coating film to perform its function more fully, the sulfonic acid (salt) group of this disclosure is more preferably a sulfonic acid group, a sodium sulfonate base, a magnesium sulfonate base, or a calcium sulfonate base, even more preferably a sodium sulfonate base, a magnesium sulfonate base, or a calcium sulfonate base, and particularly preferably a sodium sulfonate base.

In the sulfosuccinic acid (salt) skeleton of this disclosure, a hydrogen atom and/or a monovalent substituent other than a hydrogen atom are further bonded. The compound having the sulfosuccinic acid (salt) skeleton may have a reactive carbon-carbon unsaturated bond and become a constituent unit of the polymer in the emulsion during polymerization. Examples of compounds having a sulfosuccinic acid (salt) skeleton with a reactive carbon-carbon unsaturated bond include Eleminor JS-20 (trade name, manufactured by Sanyo Chemical Industries, Ltd.). However, from the viewpoint of improving the appearance of the coating film, it is preferable that the above-mentioned sulfosuccinic acid (salt) skeleton is a compound that does not have a reactive carbon-carbon unsaturated bond. In other words, the above-mentioned sulfosuccinic acid (salt) skeleton is an emulsifier for obtaining an emulsion and is preferably a non-reactive emulsifier. Since a non-reactive emulsifier does not have a reactive carbon-carbon unsaturated bond, it does not constitute part of the polymer that reacts to form an emulsion during emulsion polymerization and remains a separate compound from the polymer even after emulsion polymerization. When a compound lacking a reactive carbon-carbon unsaturated bond is used as the compound having a sulfosuccinic acid (salt) skeleton, the sound-absorbing composition of the present invention will contain a compound having a sulfosuccinic acid (salt) skeleton in addition to the polymer constituent units that form the emulsion. This allows the effect of the present invention in improving the appearance of the coating film to be exhibited more significantly.
Examples of the hydrogen atom and/or other monovalent substituents in this disclosure include hydrocarbon groups, amino groups, alkoxy groups, alkylamino groups, alkoxysulfonyl groups, sulfoalkyl groups, aminoalkyl groups, carboxyl groups, polyalkylene oxide chain-containing groups, alkenyloxy groups, and the like. For example, the compound having the sulfosuccinic acid (salt) skeleton preferably has a hydrocarbon group, more preferably has a hydrocarbon group having 8 or more carbon atoms, and even more preferably has a hydrocarbon group having 12 or more carbon atoms.

Compounds having a sulfosuccinic acid (salt) skeleton according to this disclosure may also preferably have a polyalkylene oxide chain-containing group. The polyalkylene oxide chain-containing group may be a group consisting only of a polyalkylene oxide chain, or a group having a polyalkylene oxide chain and other structural sites. Examples of other structural sites include hydrocarbon groups such as aliphatic saturated hydrocarbon groups and aromatic hydrocarbon groups. The polyalkylene oxide chain-containing group is preferably a group consisting only of a polyalkylene oxide chain, or a group in which a hydrogen atom or hydrocarbon site is bonded to the oxygen atom at the end of the polyalkylene oxide chain. For example, it is more preferable that the compound having a sulfosuccinic acid (salt) skeleton has a polyalkylene oxide chain-containing group, and that a hydrocarbon site having 8 or more carbon atoms is bonded to the end of the polyalkylene oxide chain-containing group, and even more preferable that a hydrocarbon site having 12 or more carbon atoms is bonded.
The compounds having a sulfosuccinic acid (salt) skeleton of the present disclosure preferably have an average number of moles of oxyalkylene groups added to the polyalkylene oxide chain of 3 or more, more preferably 4 or more, and even more preferably 5 or more. The average number of moles added means the average number of moles of oxyalkylene groups added to 1 mole of polyalkylene oxide chain in the above-mentioned compounds having a sulfosuccinic acid (salt) skeleton.

Compounds having a sulfosuccinic acid (salt) skeleton that lack the reactive carbon-carbon unsaturated bond described above are, for example, those with the following general formula (1):

Preferably, the formula is represented as follows: (In the formula, R1 represents a hydrogen atom or a monovalent alkyl group having 1 to 30 carbon atoms. -A- represents -O- or -NH-. R2 represents an alkylene group having 1 to 30 carbon atoms. The average number of moles added, n, is 0 to 200. X and Y are the same or different, and represent a hydrogen atom or a sulfonic acid (salt) group. At least one of X and Y represents a sulfonic acid (salt) group. R3 represents a hydrogen atom, an alkyl group, a metal salt, an ammonium salt, or an organic amine salt.)
The above R1 preferably represents a monovalent alkyl group having 1 to 30 carbon atoms. The number of carbon atoms in R1 is preferably 4 or more, more preferably 8 or more, and even more preferably 12 or more. Furthermore, the number of carbon atoms in R1 is preferably 25 or less, and more preferably 20 or less.
Furthermore, the monovalent alkyl group is preferably a primary alkyl group or a secondary alkyl group.
From the viewpoint of improving the sound absorption of high-frequency sounds, it is preferable that -A- represents -NH-.
The above R2 is preferably mainly composed of alkylene groups having 2 to 4 carbon atoms, such as ethylene, propylene, and butylene groups, and more preferably mainly composed of ethylene groups.
In this context, "main component" refers to the (R2O)n moiety, which is preferably composed of two or more oxyalkylene groups, and which accounts for 50 to 100 mol% of the total number of R2 groups.
It is more preferable that the (R2O)n portion described above is composed solely of ethylene groups.
In the sound-absorbing material composition of the present invention, the average number of moles added n is 3 to 200. From the viewpoint of further enhancing the function of the compound having the sulfosuccinic acid (salt) skeleton as an emulsifier and improving sound absorption, the average number of moles added n is more preferably 4 or more, even more preferably 5 or more, even more preferably 6 or more, and particularly preferably 7 or more. Furthermore, the average number of moles added n is more preferably 100 or less, even more preferably 50 or less, even more preferably 20 or less, and particularly preferably 10 or less.

The above X and Y may be the same or different, representing a hydrogen atom or a sulfonic acid (salt) group. At least one of X and Y represents a sulfonic acid (salt) group. Preferably, one of X or Y represents a sulfonic acid (salt) group and the other represents a hydrogen atom. The preferred form of the sulfonic acid (salt) group is as described above.
The above R3 represents a hydrogen atom, an alkyl group, a metal salt, an ammonium salt, or an organic amine salt. It is more preferable that R3 is an alkyl group or a metal salt, and even more preferable that it is a metal salt. Examples of metal atoms constituting the metal salt include alkali metal atoms such as lithium, sodium, and potassium, with sodium being particularly preferred. The alkyl group and organic amine salt in R3 are the same as those described above.

Compounds having a sulfosuccinic acid (salt) skeleton that lack the reactive carbon-carbon unsaturated bond described above are, for example, those represented by the following general formula (2):

One preferred form of the sound-absorbing material composition of the present invention is that it is represented by the formula (wherein R1, -A-, and average number of added moles n are the same as those described above in general formula (1).

Furthermore, the above-mentioned -A- represents -NH-, and the above-mentioned average number of added moles n is 0, which is also one of the preferred forms of the sound-absorbing material composition of the present invention.
In the compounds having a sulfosuccinic acid (salt) skeleton of the present disclosure, from the viewpoint of sound absorption, it is preferable that -A- represents -NH- and the average number of added moles n is 0. Specifically, examples include N-alkylmonoamide disodium sulfosuccinate, and examples of N-alkylmonoamide disodium sulfosuccinate include compounds represented by the following general formula (2).

(In the formula, R represents an alkyl group having 14 to 20 carbon atoms.)
The above-mentioned compounds having a sulfosuccinic acid (salt) skeleton can be obtained, for example, by reacting sulfosuccinic acid with a substituted compound using conventionally known methods. When the substituent is a polyalkylene oxide chain-containing group, for example, the polyalkylene oxide chain-containing group can be introduced into the sulfosuccinic acid (salt) skeleton by reacting an alkylene oxide such as ethylene oxide or a compound having a polyalkylene oxide chain with the carboxylic acid group of sulfosuccinic acid. Furthermore, commercially available products or commercially available products with their solid content concentration adjusted appropriately by adding an aqueous solvent can be used as the above-mentioned compounds having a sulfosuccinic acid (salt) skeleton.

The sound-absorbing material composition of this disclosure may be a resin composition containing a polymer.
The polymers of this disclosure preferably contain structural units derived from (meth)acrylic acid monomers, from the viewpoint of improving the dispersibility of inorganic pigments and the like when the sound-absorbing composition is used as a paint.
The (meth)acrylic acid monomers of this disclosure are monomers having at least one group, which is an acryloyl group or a methacryloyl group, or a group in which a hydrogen atom in these groups is replaced by another atom or group of atoms, and which has a carboxyl group (-COOH group) or an acid anhydride group (-C(=O)-O-C(=O)- group) having a carbonyl group in the group. The (meth)acrylic acid monomer is preferably (meth)acrylic acid.
The salts of the (meth)acrylic acid monomers in this disclosure are preferably metal salts, ammonium salts, organic amine salts, etc. Examples of metal salts and organic amine salts include those similar to those described above, which are salts of monomer units having a carbone base.

The polymers of this disclosure may have structural units other than those derived from (meth)acrylic acid monomers.
Structural units other than those derived from (meth)acrylic acid monomers include structural units derived from (meth)acrylic monomers, structural units derived from unsaturated monomers having aromatic rings, and structural units derived from other copolymerizable unsaturated monomers. The (meth)acrylic monomers other than the structural units derived from (meth)acrylic acid monomers mentioned above refer to monomers or derivatives of such monomers that have an acryloyl group or a methacryloyl group, or a group in which a hydrogen atom in these groups is replaced by another atom or group of atoms, and in which the carboxyl group is in the form of an ester or a salt.

Examples of the (meth)acrylic monomers of this disclosure include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, pentyl acrylate, pentyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, octyl acrylate, octyl methacrylate, isooctyl acrylate, isooctyl methacrylate, nonyl acrylate, nonyl methacrylate, isononyl acrylate, isononyl methacrylate, decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate, Examples include tridecyl acrylate, tridecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, vinyl formate, vinyl acetate, vinyl propionate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, diallyl phthalate, triallyl cyanurate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, allyl acrylate, allyl methacrylate, etc. It is preferable to use one or more of these.

Examples of unsaturated monomers having aromatic rings in this disclosure include divinylbenzene, styrene, α-methylstyrene, vinyltoluene, and ethylvinylbenzene, with styrene being preferred. In other words, a styrene (meth)acrylic polymer obtained from a monomer component containing styrene is also one of the preferred embodiments of the present invention. This form allows the effects of the present invention to be fully realized while reducing costs.

Other copolymerizable unsaturated monomers of this disclosure include, for example, acrylonitrile and polyfunctional unsaturated monomers such as trimethylolpropanediallyl ether.

The content of structural units derived from (meth)acrylic acid monomers per 100 parts by mass of the polymer disclosed herein is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, particularly preferably 0.7 parts by mass or more, preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less. By keeping the content within this range, it is expected that the monomer components will copolymerize stably.
The content of structural units derived from (meth)acrylic monomers per 100 parts by mass of the polymer disclosed herein is preferably 20 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 60 parts by mass or more, preferably 99.9 parts by mass or less, more preferably 99.5 parts by mass or less, and even more preferably 99.0 parts by mass or less.

The content of structural units derived from unsaturated monomers having aromatic rings per 100 parts by mass of the polymer of this disclosure is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, particularly preferably 20 parts by mass or more, even more preferably 40 parts by mass or more, preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less.

The weight-average molecular weight of the polymers disclosed herein is preferably 20,000 or more, more preferably 30,000 or more, even more preferably 35,000 or more, particularly preferably 50,000 or more, then 90,000 or more, preferably 800,000 or less, more preferably 500,000 or less, even more preferably 420,000 or less, and particularly preferably 400,000 or less, then 270,000 or less. The weight-average molecular weight of the polymers disclosed herein can be measured by known methods, but it can also be measured using GPC under the conditions described in the examples below.

The glass transition temperature (Tg) of the polymers of this disclosure is preferably -20°C or higher, more preferably -15°C, even more preferably -10°C or higher, preferably 40°C or lower, more preferably 35°C or lower, and even more preferably 30°C or lower.
The glass transition temperature of the polymer in this disclosure is calculated using the glass transition temperature of the monomer homopolymer used in the monomer components constituting the polymer, using formula (I):

[In the formula, Tg' is the Tg (absolute temperature) of the polymer. W1', W2', ..., Wn' are the mass fractions of each monomer relative to the total monomer components. T1, T2, ..., Tn are the glass transition temperatures (absolute temperatures) of the homopolymers (single polymers) composed of each monomer component.]
The temperature may be determined based on Fox's formula, which is expressed as follows:
For monomers whose glass transition temperature is unknown, such as special monomers and polyfunctional monomers, if the total amount of monomers with unknown glass transition temperatures in the monomer component is 10% by mass or less, the glass transition temperature can be determined using only monomers with known glass transition temperatures. If the total amount of monomers with unknown glass transition temperatures in the monomer component exceeds 10% by mass, the glass transition temperature of the polymer can be determined by differential scanning calorimetry (DSC), differential calorimetry (DTA), thermomechanical analysis (TMA), etc.
The glass transition temperature of a polymer can be easily adjusted by adjusting the composition of its monomer components. The composition of the monomer components used as raw materials for the polymer constituting the emulsion particles can be determined by considering the glass transition temperature of the polymer constituting the emulsion particles.
The glass transition temperatures of polymers are, for example, -70°C for 2-ethylhexyl acrylate homopolymers, -56°C for n-butyl acrylate homopolymers, 100°C for styrene homopolymers, and 95°C for acrylic acid homopolymers.

The content of the compound having a sulfosuccinic acid (salt) skeleton per 100 parts by mass of the polymer of this disclosure is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, from the viewpoint of sound absorption; preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less, from the viewpoint of film-forming properties.

The polymer of this disclosure is preferably in the form of emulsion particles, and more preferably in the form of an aqueous dispersion containing emulsion particles from the viewpoint of environmental protection and worker safety.
In this specification, an aqueous dispersion means a dispersion in which a polymer is dispersed in an aqueous solvent. The aqueous solvent may include other organic solvents as long as it contains water, but water is preferred.
The water content per 100 parts by mass of the aqueous solvent of this disclosure is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, even more preferably 95 parts by mass or more, and may also be 100 parts by mass.

The sound-absorbing composition of this disclosure may contain one type of emulsion particle, or it may contain two or more types. When it contains two or more types of emulsions according to the present invention, it may be a mixture obtained by mixing (blending) two or more types of emulsions according to the present invention, or it may be an emulsion of two or more polymer chains obtained by producing a material containing two or more polymer chains in a series of manufacturing steps (for example, by multi-stage polymerization).
The composite of two or more polymer chains of this disclosure includes, for example, a form having a core portion and a shell portion, as described later.
One example of a form having a core and a shell portion of the present disclosure is an emulsion consisting of two types of emulsions according to the present invention, where one of the two types of emulsions according to the present invention forms the core portion and the other forms the shell portion. It should be noted that the above polymer is a polymer obtained using monomer components containing structural units derived from (meth)acrylic acid monomers, for example, the (meth)acrylic acid monomer may be contained in either the monomer component forming the core portion of the emulsion, the monomer component forming the shell portion, or both.

When the emulsion particles of this disclosure are in a form in which two or more polymer chains are compounded, one polymer chain and the other polymer chain may be completely miscible, resulting in a homogeneous structure indistinguishable from each other, or they may be heterogeneously formed without complete miscibility (for example, a core-shell composite structure or a microdomain structure). Among these structures, a core-shell composite structure is preferred in order to fully bring out the properties of the emulsion and produce a stable emulsion. Emulsions having a core-shell composite structure exhibit excellent vibration damping over a wide range within the practical temperature range. In particular, even in the high-temperature range, they exhibit superior vibration damping compared to other forms of sound-absorbing resin compositions, and as a result, vibration damping performance can be exhibited over a wide range from room temperature to high temperatures within the practical temperature range. In the above core-shell composite structure, it is preferable that the surface of the core portion is covered by the shell portion. In this case, it is preferable that the surface of the core portion is completely covered by the shell portion, but it does not have to be completely covered, for example, it may be covered in a mesh-like manner, or the core portion may be exposed in places.

When the emulsion particles of this disclosure are in a form in which two or more polymer chains are compounded, the glass transition temperature (Tg) refers to the Tg (total Tg) calculated from the monomer composition used in all stages.
When the emulsion particles of this disclosure are in a form in which at least one is a composite of two or more polymer chains, the glass transition temperature of one polymer chain (e.g., the polymer chain of the core) is preferably 0 to 60°C, more preferably 10 to 50°C. The glass transition temperature of the other polymer chain (e.g., the polymer chain of the shell) is preferably -30 to 30°C, more preferably -20 to 20°C. The difference in glass transition temperatures between one polymer chain and the other is preferably 5 to 60°C. By providing such a difference in glass transition temperatures, for example, when applied to sound-absorbing materials, it becomes possible to exhibit higher vibration damping performance over a wide temperature range, and in particular, vibration damping performance in the practical range of 20 to 60°C is further improved. The difference in glass transition temperatures is more preferably 10 to 50°C, and even more preferably 20 to 40°C.

The average particle size of the emulsion particles in this disclosure is preferably 80 to 450 nm. By using emulsion particles with an average particle size within this range, it is possible to achieve sufficient basic performance, such as the appearance of the coating and coating properties required for sound-absorbing materials, while also making the sound-absorbing material superior. More preferably, the average particle size of the emulsion particles is 400 nm or less, and even more preferably 350 nm or less. Furthermore, the average particle size is preferably 100 nm or more. The average particle size of the emulsion particles can be measured by the method described in the examples below.

The pH of the sound-absorbing composition of this disclosure is not particularly limited, but is preferably 2 to 10, more preferably 3 to 9.5, and even more preferably 7 to 9.
When the sound-absorbing composition of this disclosure is an aqueous dispersion containing emulsion particles, the pH can be adjusted by adding ammonia water, water-soluble amines, alkali hydroxide aqueous solution, etc., to the resin. The pH described in this disclosure can be measured by the method described in the examples below.
The viscosity of the sound-absorbing composition of this disclosure is not particularly limited, but is preferably 1 to 10,000 mPa·s, more preferably 5 to 4,000 mPa·s, even more preferably 10 to 2,000 mPa·s, even more preferably 30 to 1,000 mPa·s, and particularly preferably 80 to 500 mPa·s. The viscosity described in this disclosure can be measured by the conditions described in the examples described later.

The sound-absorbing compositions of this disclosure may contain anionic emulsifiers other than compounds having a sulfosuccinic acid (salt) skeleton.
Anionic emulsifiers other than compounds having a sulfosuccinate (salt) skeleton include polyoxyalkylene alkyl ether sulfates, polyoxyalkylene oleyl ether sodium sulfates, polyoxyalkylene alkylphenyl ether sulfates, alkyl diphenyl ether disulfonates, polyoxyalkylene (mono, di, tri)styrylphenyl ether sulfates, polyoxyalkylene (mono, di, tri)benzylphenyl ether sulfates, alkenyl succinate disalts; alkyl sulfate salts such as sodium dodecyl sulfate, potassium dodecyl sulfate, and ammonium alkyl sulfate; and sodium dodecyl polyglycols. Examples include ether sulfates; sodium sulfolisinoates; alkyl sulfonates such as sulfonated paraffin salts; alkyl sulfonates such as sodium dodecylbenzene sulfonate and alkali metal sulfates of alkali phenol hydroxyethylene; high alkylnaphthalene sulfonates; naphthalene sulfonic acid formalin condensates; fatty acid salts such as sodium laurate, triethanolamine oleate, and triethanolamine abietate; polyoxyalkyl ether sulfates; polyoxyethylene carboxylic acid sulfates; polyoxyethylene phenyl ether sulfates; and polyoxyethylene alkylaryl sulfates.
Commercially available anionic emulsifiers other than compounds having a sulfosuccinic acid (salt) skeleton include polyoxyalkylene alkyl ether sulfates such as Revenol WX (trade name, polyoxyethylene alkyl ether sulfate sodium, manufactured by Kao Corporation); polyoxyalkylene polycyclic phenyl ether sulfates such as Newcol 707SF (trade name, polyoxyethylene polycyclic phenyl ether sulfate salt, manufactured by Nippon Emulsifier Co., Ltd.); alkyl diphenyl ether disulfonates; reactive anionic emulsifiers such as alkenyl succinate type anionic emulsifiers; and other commonly used anionic emulsifiers (e.g., sodium lauryl sulfate), one or more of these can be used.

The sound-absorbing composition of this disclosure may contain anionic emulsifiers other than those having a sulfosuccinic acid (salt) skeleton. However, it is preferable that the content of the compound having a sulfosuccinic acid (salt) skeleton is 25% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 100% by mass, based on 100% by mass of the anionic emulsifier in the composition.

The content of the sulfosuccinic acid (salt) skeleton compound per 100 parts by mass of nonvolatile matter of the sound-absorbing composition disclosed herein is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and still preferably 1.5 parts by mass or more from the viewpoint of sound absorption, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and still preferably 10 parts by mass or less from the viewpoint of film-forming properties.
The non-volatile content of the sound-absorbing composition disclosed herein may be calculated as the total mass of the sound-absorbing composition excluding the mass of volatile components contained in the polymer and various additives, or 1 g of the sound-absorbing composition may be weighed, dried in a hot air dryer at a temperature of 110°C for 1 hour, and the resulting residue may be used as the non-volatile content, with formula:
[Non-volatile content (mass%) in sound-absorbing material compositions]
= ([Mass of residue] ÷ [1g of sound-absorbing material composition]) × 100
It may also be calculated based on this.

Furthermore, the sound-absorbing composition described herein refers to a composition that does not contain inorganic particles. When the sound-absorbing composition or inorganic particles are included, it will be treated as a sound-absorbing coating.

The nonvolatile content of the sound-absorbing composition of this disclosure is preferably 40 parts by mass or more, more preferably 45 parts by mass or more, and even more preferably 50 parts by mass or more, from the viewpoint of sound absorption, preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 60 parts by mass or less, from the viewpoint of film-forming properties.
The polymer content in 100 parts by mass of the nonvolatile content of the sound-absorbing composition of the present disclosure is preferably 35 parts by mass or more, more preferably 40 parts by mass or more, and still preferably 45 parts by mass or more, from the viewpoint of sound absorption, preferably 99 parts by mass or less, more preferably 97 parts by mass or less, and still preferably 95 parts by mass or less, from the viewpoint of mechanical stability.
In the sound-absorbing composition of the present disclosure, the content of the compound having a sulfosuccinic acid (salt) skeleton per 100 parts by mass of polymer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and still more preferably 3 parts by mass or more, and from the viewpoint of film-forming properties, preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and still more preferably 10 parts by mass or less.

The sound-absorbing material composition of this disclosure may be a resin composition containing a foaming agent.
Examples of foaming agents in this disclosure include heat-expandable capsule-type foaming agents.
Since the sulfosuccinic acid (salt) skeleton compound of this disclosure functions as a blowing agent, the amount of conventionally used, expensive blowing agents can be reduced. For example, it is preferable to have a content of 2% by mass or less, more preferably 1% by mass or less, and most preferably 0% by mass, of the total monomer components used as raw materials for the emulsion (100% by mass).
In this specification, compounds having a sulfosuccinic acid (salt) skeleton are not included as blowing agents.

The sound-absorbing composition of this disclosure contains a compound having a sulfosuccinic acid (salt) skeleton that functions as a foaming agent when used as a sound-absorbing coating to obtain a coating film. Therefore, by reducing the content of the heat-expandable capsule-type foaming agent to 2% by mass or less, it is possible to sufficiently prevent excessive foaming agent from making it difficult to maintain the shape of the coating film, thereby achieving a superior coating film appearance.

The sound-absorbing composition of this disclosure may further contain a dispersant. Examples of the dispersant include inorganic dispersants such as sodium hexametaphosphate and sodium tripolyphosphate, and organic dispersants such as polycarboxylic acid-based dispersants. The amount of the dispersant is preferably 0.1 to 8 parts by mass, more preferably 0.5 to 6 parts by mass, and even more preferably 1 to 3 parts by mass, in terms of solid content, per 100 parts by mass of polymer in the sound-absorbing coating.
The sound-absorbing composition of this disclosure may further contain a thickening agent.
Examples of the thickening agents of this disclosure include polyvinyl alcohol, cellulose derivatives, and polycarboxylic acid resins.
The amount of the thickening agent of this disclosure is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 4 parts by mass, and even more preferably 0.3 to 2 parts by mass, per 100 parts by mass of polymer in the sound-absorbing material composition.
The sound-absorbing composition of this disclosure may further contain other components. Examples of other components include solvents, gelling agents, defoaming agents, plasticizers, stabilizers, wetting agents, preservatives, anti-foaming agents, anti-aging agents, antifungal agents, ultraviolet absorbers, antistatic agents, etc., and one or more of these can be used. The inorganic particles, dispersants, thickeners, and other components can be mixed with the polymer emulsion and crosslinking agent according to the present invention using, for example, a butterfly mixer, planetary mixer, spiral mixer, kneader, dissolver, etc.

<Method for manufacturing sound-absorbing material compositions>
The method for producing the sound-absorbing composition of this disclosure is not particularly limited as long as it contains a compound having a sulfosuccinic acid (salt) skeleton, but it is preferable to include a polymer from the viewpoint of sound absorption when used as a sound-absorbing material.
The polymer contained in the sound-absorbing composition of this disclosure may also be a commercially available polymer.
The polymer of this disclosure is preferably a polymer obtained by polymerizing (meth)acrylic acid monomers, from the viewpoint of improving the dispersibility of inorganic pigments and the like when the sound-absorbing composition is used as a paint.
Existing methods such as bulk polymerization, suspension polymerization, solution polymerization, precipitation polymerization, and emulsion polymerization can be applied to the polymers of this disclosure. Among these, emulsion polymerization is preferred from the viewpoint of reducing environmental impact, and among these, the use of an aqueous medium such as water as the solvent is more preferred from the viewpoint of safety.

The polymer of this disclosure is preferably in the form of emulsion particles, and is preferably an aqueous dispersion containing emulsion particles from the viewpoint of environmental protection and worker safety.
In this specification, an aqueous dispersion means a dispersion in which a polymer is dispersed in an aqueous solvent. The aqueous solvent may include other organic solvents as long as it contains water, but water is preferred.
The water content per 100 parts by mass of the aqueous solvent of this disclosure is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, even more preferably 95 parts by mass or more, and may also be 100 parts by mass.

The method for producing emulsion particles according to this disclosure may involve a component having a sulfosuccinic acid (salt) skeleton acting as an emulsifier to form emulsion particles.
The emulsion may be obtained by emulsion polymerization using a monomer emulsion containing all of the sulfosuccinic acid (salt) skeleton compound and monomer components as a raw material, or it may be obtained by emulsion polymerization using a monomer emulsion containing a portion of the sulfosuccinic acid (salt) skeleton compound and monomer components as a raw material to obtain an emulsion, and then adding the remainder of the sulfosuccinic acid (salt) skeleton compound to the obtained emulsion. In this way, by emulsion polymerization using a monomer emulsion containing at least a portion of the sulfosuccinic acid (salt) skeleton compound and monomer components as a raw material, at least a portion of the sulfosuccinic acid (salt) skeleton component is included as an emulsifier that forms the emulsion. In this case, at least a portion of the sulfosuccinic acid (salt) skeleton component may be a normal emulsifier (a compound separate from the polymer), or it may be a constituent unit that makes up part of the polymer and also an emulsifier.

As described above, the resin composition for sound-absorbing materials of the present invention may be obtained by emulsion polymerization of monomer components that do not contain a compound having a sulfosuccinic acid (salt) skeleton to obtain an emulsion, or by polymerization other than emulsion polymerization to obtain a polymer, and then by adding a compound having a sulfosuccinic acid (salt) skeleton as an emulsifier to the obtained emulsion or polymer. Among these, it is preferable to obtain a polymer by polymerization other than emulsion polymerization, and then add a compound having a sulfosuccinic acid (salt) skeleton as an emulsifier to the obtained polymer.
The present disclosure also relates to a method for producing emulsion particles, which includes a step of emulsion polymerization using a monomer emulsion containing a compound having a sulfosuccinic acid (salt) skeleton and a monomer component as raw materials, or a step of obtaining a polymer by polymerization other than emulsion polymerization using a monomer component as a raw material, and then adding a compound having a sulfosuccinic acid (salt) skeleton to the polymer. The polymerization temperature is not particularly limited, but is preferably 0 to 100°C. The polymerization time is also not particularly limited, but is preferably 1 to 15 hours.

<Sound-absorbing paint>
The sound-absorbing composition disclosed herein can be applied on its own to form a vibration-damping coating, but it is typically used to obtain the paint of the present invention, as described later.
The paints of this disclosure preferably contain inorganic particles.
Examples of inorganic particles in this disclosure include titanium dioxide, carbon black, iron oxide, calcium carbonate, kaolin, silica, talc, barium sulfate, alumina, iron oxide, glass tok, magnesium carbonate, aluminum hydroxide, diatomaceous earth, clay, glass flakes, mica, metal oxide whiskers, glass fibers, wollastonite, and the like.
The inorganic particles of this disclosure preferably have an average particle diameter of 1 to 50 μm. The average particle diameter of the pigment can be measured using a laser diffraction particle size distribution analyzer and is the 50% weight diameter value from the particle size distribution.
The inorganic particle content per 100 parts by mass of the sound-absorbing coating of this disclosure is preferably 10 parts by mass or more, more preferably 200 parts by mass or more, and even more preferably 300 parts by mass or more. The amount of pigment blended is preferably 900 parts by mass or less, more preferably 800 parts by mass or less, and even more preferably 500 parts by mass or less.

<Coating film>
The sound-absorbing coating of this disclosure can be heated and dried to obtain a coating film, thereby causing the coating to foam simultaneously with drying, and thus forming an evaporation path for a solvent such as water.
The coating film of this disclosure preferably has a thickness of 2 to 8 mm. This thickness is preferable considering that it exhibits more sufficient sound absorption and prevents peeling, cracking, etc. of the coating film, thereby forming a good coating film. The thickness of the coating film is more preferably 2 to 6 mm, and even more preferably 2 to 5 mm.
The substrate on which the coating film of this disclosure is formed is not particularly limited as long as a coating film can be formed on it, and may be any material such as a metal material like a steel plate or a plastic material. In particular, forming a coating film on the surface of a steel plate is one of the preferred uses of the vibration-damping coating film of the present invention.
The coating film of this disclosure can be obtained, for example, by applying the paint of the present invention using a brush, spatula, air spray, airless spray, mortar gun, stucco gun, or the like.

<Application>
The sound-absorbing composition of this disclosure is used as a sound-absorbing material.
From the viewpoint of sound absorption, the sound-absorbing material of this disclosure is preferably a foam.
As a method for producing the foam according to this disclosure, since it contains a compound having a sulfosuccinic acid (salt) skeleton, the foam can be obtained by applying the sound-absorbing composition or sound-absorbing coating to a substrate and then heating and drying it.

From the viewpoint of foam strength, the density of the foam disclosed is preferably 0.5 g/ ^cm³ or more, more preferably 0.7 g/ ^cm³ or more, and even more preferably 0.9 g/ ^cm³ or more. From the viewpoint of the sound absorption properties of the foam, the density is preferably 1.5 g/ ^cm³ or less, more preferably 1.4 g/ ^cm³ or less, and even more preferably 1.3 g/ ^cm³ or less.
The thickness of the foam in this disclosure is preferably 2 to 8 mm from the viewpoint of sound absorption. This thickness is preferable considering that it exhibits more sufficient sound absorption, prevents peeling and cracking of the coating, and forms a good coating. The thickness of the coating is more preferably 2 to 6 mm, and even more preferably 2 to 5 mm.
The sound-absorbing material of this disclosure preferably has a sound absorption coefficient measured by the normal incidence sound absorption coefficient measurement method in accordance with JIS A1405-2, with a peak at 3000 Hz to 5000 Hz, more preferably at 3000 Hz to 4500 Hz, and even more preferably at 3000 Hz to 4000 Hz.

As for the sound-absorbing material of this disclosure, when the sound absorption coefficient measured by the normal incidence sound absorption coefficient measurement method in accordance with JIS A1405-2 has a peak in 3000 Hz to 5000 Hz, the peak sound absorption coefficient is preferably 0.40 or higher, more preferably 0.45 or higher, and particularly preferably 0.50 or higher, followed by 0.55 or higher.
The sound absorption coefficient of the sound-absorbing material disclosed herein is preferably 0.40 or higher, more preferably 0.45 or higher, and most preferably 0.50 or higher, in that order, most preferably 0.55 or higher, and most preferably 0.55 or higher, as measured by the normal incidence sound absorption coefficient measurement method in accordance with JIS A1405-2 per 4 mm of sound-absorbing material.

The sound-absorbing material disclosed herein can be suitably used in transportation vehicles such as automobiles, railway vehicles, ships, and aircraft, as well as electrical equipment, building structures, and construction equipment. It is particularly preferable to use it in transportation vehicles, and by using it in vehicles with noise sources such as automobiles, trains, and aircraft, especially in electrically driven vehicles such as electric vehicles that produce noticeable high-frequency noise, it is expected to reduce discomfort while driving.
When using the sound-absorbing material of this disclosure in a vehicle, it is preferable to have a laminated structure in which the material is laminated on a motor or a casing housing a motor, from the viewpoint of reducing discomfort caused by high-frequency noise. Examples of motors include drive motors, pump motors, power generator motors, fan motors, electric power steering motors, blower motors for air conditioning and cooling systems, power window motors, and electric power seat motors, which are installed in electric vehicles and hybrid vehicles.

<Sound absorption methods>
Another aspect of the present invention is a sound absorption method for which a coating film formed from a composition containing a compound having a sulfosuccinic acid (salt) skeleton (hereinafter also referred to as composition (X)) absorbs sound. Specifically, the present invention is a sound absorption method for which a coating film formed from a composition containing a compound having a sulfosuccinic acid (salt) skeleton absorbs sound containing components in the frequency range of 3000 Hz to 5000 Hz.
As mentioned above, compounds having a sulfosuccinic acid (salt) skeleton are as follows.
The composition (X) of this disclosure contains a compound having a sulfosuccinic acid (salt) skeleton, but preferably also contains a polymer.
The polymer is as described above, and preferred embodiments of composition (X) are the same as those of the sound-absorbing resin composition described herein.
In the composition (X) of the present disclosure, the amount of the compound having a sulfosuccinic acid (salt) skeleton per 100 parts by mass of the polymer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and still more preferably 3 parts by mass or more from the viewpoint of sound absorption, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and still more preferably 10 parts by mass or less from the viewpoint of film-forming properties.
The composition (X) of this disclosure preferably contains 10% by mass or more and 70% by mass or less of a polymer.

Composition (X) may contain inorganic particles. Preferred embodiments and content of inorganic particles in composition (X) are the same as those of the sound-absorbing coating described herein.
Composition (X) may contain water, preferably in an amount of 10% by mass or more and 60% by mass or less.
In the sound absorption method of this disclosure, the method for forming a coating film from composition (X) and the form of the coating film are preferably the same as described above.
In the sound absorption method of this disclosure, there are no particular restrictions on the sound to be absorbed, but it is preferable that the sound includes components within the frequency range of 3000 Hz to 5000 Hz.

The present invention will now be described in more detail based on examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, "parts" means "parts by mass" and "%" means "percent mass".
In the following examples and comparative examples, the properties of various resins were evaluated as follows.

<Non-volatile content (solids)>
Approximately 1 g of the obtained emulsion was weighed and dried in a hot air dryer at 150°C for 1 hour. The remaining amount after drying was considered non-volatile and expressed as a mass % relative to the mass before drying.
<Average particle diameter>
The average particle size of the emulsion particles was measured using a particle size distribution analyzer (Otsuka Electronics Co., Ltd. FPAR-1000) that employs dynamic light scattering.
<Weight average molecular weight>
The measurements were performed by GPC (gel permeation chromatography) under the following conditions.
Measuring instrument: HLC-8120GPC (product name, manufactured by Tosoh Corporation)
Molecular weight columns: TSK-GEL GMHXL-L and TSK-GELG5000HXL (both manufactured by Tosoh Corporation) are used connected in series.
Eluent: Tetrahydrofuran (THF)
Calibration standard material: Polystyrene (manufactured by Tosoh Corporation)
Measurement method: The substance to be measured is dissolved in THF to a solid content of approximately 0.2% by mass, filtered, and the molecular weight is measured using the resulting sample.

<Method for measuring sound absorption coefficient>
The sound absorption coefficient was measured according to JIS A1405-2, using a WinZac manufactured by Nippon Acoustic Engineering Co., Ltd., under rigid wall contact conditions with no air gap behind the sound source, specifically the normal incidence sound absorption coefficient.
<Preparation of sound absorption coefficient measurement samples>
The sound-absorbing material was formulated as described below and applied to a steel plate (product name SPCC-SD, 75 mm wide x 150 mm long x 0.8 mm thick, manufactured by Nippon Test Panel Co., Ltd.) to a thickness of 3 mm. It was then dried in a hot air dryer at 150°C for 50 minutes. The dried film was peeled from the steel plate and cut into pieces 40 mm in diameter and 4 mm thick to obtain measurement samples. Sound absorption measurements were taken using the surface that was in close contact with the steel plate.
• Resin composition 1-15: 1000 parts (solid content) • Calcium carbonate NN#200*1: 1600 parts • Dispersant Aquaric DL-40S*2: 20 parts • Thickener Acryset WR-650*3: 25 parts • Antifoaming agent Nopco 8034L*4: 3 parts • Foaming agent F-30*5: 10 parts *1: Manufactured by Nitto Funka Kogyo Co., Ltd. Filler *2: Manufactured by Nippon Shokubai Co., Ltd. Polycarboxylic acid type dispersant (active ingredient 44%)
*3: Alkali-soluble acrylic thickener manufactured by Nippon Shokubai Co., Ltd. (active ingredient 30%)
*4: Antifoaming agent manufactured by Sunopco Corporation (main components: hydrophobic silicone + mineral oil)
*5: Foaming agent manufactured by Matsumoto Oil & Fat Co., Ltd.

<Glass transition temperature (Tg) of polymers>
The Tg of the polymer was calculated from the monomer composition used in each step using the following formula (1).

In the formula, Tg' is the Tg (absolute temperature) of the polymer. W1', W2', ..., Wn' are the mass fractions of each monomer relative to the total monomer components. T1, T2, ..., Tn are the glass transition temperatures (absolute temperatures) of the homopolymers (single polymers) composed of each monomer component.
The Tg calculated from the monomer composition used in all stages is listed as "Total Tg".
The Tg values of each homopolymer used to calculate the glass transition temperature (Tg) of the polymerizable monomer component using the above formula (1) are shown below.
Styrene (St): 100°C
2-Ethylhexyl acrylate (2EHA): -70°C
Butyl acrylate (BA): -56°C
Acrylic acid (AA): 95°C

The emulsifier used in the following examples will be described.
N-alkylmonamide disodium sulfosuccinate is given by the following formula (i):

The compound is represented by the formula (wherein R represents an alkyl group having 14 to 20 carbon atoms). In this specification, this compound is also represented as (i).

The polyoxyethylene alkyl ether sulfosuccinate hemiester salt is given by the following formula (ii):

This is a compound represented by the formula (wherein R represents a secondary alkyl group having 12 to 14 carbon atoms).
In the formula, n represents the average number of moles added. In this specification, compounds with n=9 are also represented as (ii)-<1>.
Polyoxyethylene alkyl ether sulfosuccinate disodium salt is given by the following formula (iii):

This is a compound represented by the formula, where n represents the average number of moles added. In this specification, the compound with n=8 is also represented as (iii)-<1>.

The commercially available emulsifiers used in the examples and comparative examples will be described below.
Newcol 707SF (product name, polyoxyethylene polycyclic phenyl ether sulfate: manufactured by Nippon Emulsifier Co., Ltd.)
Revenol WX (product name, sodium polyoxyethylene alkyl ether sulfate: manufactured by Kao Corporation)

(Example 1)
410.0 parts of deionized water were charged into a polymerization reactor equipped with a stirrer, reflux condenser, thermometer, nitrogen inlet tube, and dropping funnel. The internal temperature was then raised to 75°C while stirring under a nitrogen gas flow. Meanwhile, a monomer emulsion consisting of 222.0 parts of styrene, 172.0 parts of 2-ethylhexyl acrylate, 6.0 parts of acrylic acid, 3.6 parts of t-dodecyl mercaptan (also called t-DM) as a polymerization chain transfer agent, 100.0 parts of N-alkylmonoamide disodium (i) sulfosuccinate, which had been prepared as a 20% aqueous solution in advance, 24.0 parts of polyoxyethylene alkyl ether sulfosuccinate disodium salt (iii)-<1>, and 40.0 parts of deionized water was charged into the dropping funnel. Next, while maintaining the internal temperature of the polymerizer at 75°C, 14.0 parts of the monomer emulsion, 10 parts of a 2.5% potassium persulfate aqueous solution and 10 parts of a 2% sodium bisulfite aqueous solution, which are polymerization initiators (oxidizing agents), were added to start the initial polymerization. After 40 minutes, while maintaining the reaction system temperature at 80°C, the remaining monomer emulsion was uniformly added dropwise over 80 minutes. Simultaneously, 76 parts of a 2.5% potassium persulfate aqueous solution and 36 parts of a 2% sodium bisulfite aqueous solution were uniformly added dropwise over 80 minutes. After the addition was complete, the temperature was maintained for 60 minutes to obtain an aqueous dispersion of an acrylic copolymer with a glass transition temperature of 1.2°C, which forms the core of the multilayered emulsion particles.
Next, a monomer emulsion consisting of 244.0 parts styrene, 347.0 parts butyl acrylate, 9.0 parts acrylic acid, 5.4 parts t-DM, 150.0 parts N-alkylmonamide disodium (i) sulfosuccinate (iii)-<1) pre-prepared as a 20% aqueous solution, 36.0 parts polyoxyethylene alkyl ether sulfosuccinate disodium salt (iii)-<1>, and 60.0 parts deionized water was charged into a dropping funnel as monomers to form the shell. This emulsion was uniformly added dropwise over 120 minutes to the aqueous dispersion of the acrylic copolymer obtained above. Simultaneously, 114 parts of 2.5% potassium persulfate aqueous solution and 54 parts of 2% sodium bisulfite aqueous solution were uniformly added dropwise over 120 minutes. After the addition of the drops, the temperature was maintained for 120 minutes to form a shell with a glass transition temperature of -9.6°C. After cooling the resulting reaction solution to room temperature, 18.6 parts of 2-dimethylethanolamine were added to obtain an acrylic emulsion (resin composition 1) with a non-volatile content of 50.3%, an average particle size of 150 nm, and a weight-average molecular weight of 28,000.

(Example 2)
In the preparation of the monomer emulsion in Example 1, the amount of t-DM in the first step was changed from 3.6 parts to 0.8 parts, and the amount of t-DM in the second step was changed from 5.4 parts to 1.2 parts. The same procedure as in Example 1 was followed to obtain an acrylic emulsion (resin composition 2) with a non-volatile content of 50.0%, an average particle size of 145 nm, and a weight-average molecular weight of 76,000.
(Example 3)
In the preparation of the monomer emulsion in Example 1, 100.0 parts of polyoxyethylene alkyl ether sulfosuccinate (ii)-<1>, which had been prepared in advance to a 20% aqueous solution, were used instead of 100.0 parts of N-alkylmonoamide disodium sulfosuccinate (i) that had been prepared in advance to a 20% aqueous solution in the first step, and 150.0 parts of polyoxyethylene alkyl ether sulfosuccinate (ii)-<1>, which had been prepared in advance to a 20% aqueous solution, were used instead of 150.0 parts of N-alkylmonoamide disodium sulfosuccinate (i) that had been prepared in advance to a 20% aqueous solution in the second step. The same procedure as in Example 1 was followed to obtain an acrylic emulsion (resin composition 3) with a non-volatile content of 50.1%, an average particle size of 150 nm, and a weight-average molecular weight of 31,000.

(Example 4)
In Example 1, the amount of deionized water was changed from 408.0 parts to 355.0 parts in the polymerizer preparation. In the monomer emulsion preparation, the amount of N-alkylmonoamide disodium sulfosuccinate (i), which had been pre-prepared as a 20% aqueous solution, was changed from 100.0 parts to 80.0 parts and the amount of deionized water from 40.0 parts to 60.0 parts in the first step. In the second step, the amount of N-alkylmonoamide disodium sulfosuccinate (i), which had been pre-prepared as a 20% aqueous solution, was changed from 150.0 parts to 120.0 parts and the amount of deionized water from 60.0 parts to 90.0 parts. Otherwise, the same procedure as in Example 1 was performed to obtain an acrylic emulsion (resin composition 4) with a non-volatile content of 51.0%, an average particle size of 160 nm, and a weight-average molecular weight of 28,000.
(Example 5)
In the preparation of the monomer emulsion in Example 4, 80.0 parts of polyoxyethylene alkyl ether sulfosuccinate (ii)-<1>, which had been prepared in advance to a 20% aqueous solution, were used instead of 80.0 parts of N-alkylmonoamide disodium sulfosuccinate (i) that had been prepared in advance to a 20% aqueous solution in the first step, and 120.0 parts of polyoxyethylene alkyl ether sulfosuccinate (ii)-<1>, which had been prepared in advance to a 20% aqueous solution, were used instead of 120.0 parts of N-alkylmonoamide disodium sulfosuccinate (i) that had been prepared in advance to a 20% aqueous solution in the second step. The same procedure as in Example 4 was followed to obtain an acrylic emulsion (resin composition 5) with a non-volatile content of 51.1%, an average particle size of 160 nm, and a weight-average molecular weight of 32,000.

(Example 6)
In Example 1, the amount of deionized water was changed from 408.0 parts to 305.0 parts in the polymerizer preparation. In the monomer emulsion preparation, the amount of N-alkylmonoamide disodium sulfosuccinate (i), which had been pre-prepared as a 20% aqueous solution, was changed from 100.0 parts to 75.0 parts and the amount of deionized water from 40.0 parts to 60.0 parts in the first step. In the second step, the amount of N-alkylmonoamide disodium sulfosuccinate (i), which had been pre-prepared as a 20% aqueous solution, was changed from 150.0 parts to 112.5 parts and the amount of deionized water from 60.0 parts to 90.0 parts. Otherwise, the same procedure as in Example 1 was performed to obtain an acrylic emulsion (resin composition 6) with a non-volatile content of 52.5%, an average particle size of 145 nm, and a weight-average molecular weight of 33,000.
(Example 7)
In the preparation of the monomer emulsion in Example 6, 75.0 parts of polyoxyethylene alkyl ether sulfosuccinate (ii)-<1>, which had been prepared in advance to a 20% aqueous solution, were used instead of 75.0 parts of N-alkylmonoamide disodium sulfosuccinate (i) that had been prepared in advance to a 20% aqueous solution in the first step, and 112.5 parts of polyoxyethylene alkyl ether sulfosuccinate (ii)-<1>, which had been prepared in advance to a 20% aqueous solution, were used instead of 112.5 parts of N-alkylmonoamide disodium sulfosuccinate (i) that had been prepared in advance to a 20% aqueous solution in the second step. The same procedure as in Example 6 was followed to obtain an acrylic emulsion (resin composition 7) with a non-volatile content of 52.4%, an average particle size of 150 nm, and a weight-average molecular weight of 31,000.

(Example 8)
In the preparation of the monomer emulsion in Example 1, the amount of N-alkylmonoamide disodium sulfosuccinate (i), which had been pre-prepared as a 20% aqueous solution, was changed from 100.0 parts to 50.0 parts and the amount of deionized water from 40.0 parts to 75.0 parts in the first step. In the second step, the amount of N-alkylmonoamide disodium sulfosuccinate (i), which had been pre-prepared as a 20% aqueous solution, was changed from 150.0 parts to 75.0 parts and the amount of deionized water from 60.0 parts to 110.0 parts. Otherwise, the same procedure as in Example 1 was performed to obtain an acrylic emulsion (resin composition 8) with a non-volatile content of 49.6%, an average particle size of 195 nm, and a weight-average molecular weight of 29,000.
(Example 9)
Except for changing the amount of deionized water added in the polymerization reactor in Example 1 from 408.0 parts to 215.0 parts, the same procedure as in Example 1 was performed to obtain an acrylic emulsion (resin composition 9) with a non-volatile content of 55.3%, an average particle size of 165 nm, and a weight-average molecular weight of 32,000.

(Example 10)
In Example 1, the amount of deionized water was changed from 408.0 parts to 307.0 parts in the polymerizer preparation. In the monomer emulsion preparation, the amount of N-alkylmonoamide disodium sulfosuccinate (i), which had been pre-prepared as a 20% aqueous solution, was changed from 100.0 parts to 66.0 parts in the first step, the amount of deionized water was changed from 40.0 parts to 70.0 parts, and the amount of t-DM was changed from 3.6 parts to 1.6 parts. In the second step, the amount of N-alkylmonoamide disodium sulfosuccinate (i), which had been pre-prepared as a 20% aqueous solution, was changed from 150.0 parts to 100.0 parts, the amount of deionized water was changed from 60.0 parts to 105.0 parts, and the amount of t-DM was changed from 5.4 parts to 2.4 parts. Otherwise, the same procedure as in Example 1 was performed to obtain an acrylic emulsion (resin composition 10) with a non-volatile content of 51.8%, an average particle size of 165 nm, and a weight-average molecular weight of 49,000.

(Comparative Example 1)
In the deionized water charge in the polymerization reactor of Example 10, the amount was changed from 307.0 parts to 320.0 parts, and in the monomer emulsion charge, the first charge was changed from 66.0 parts of N-alkylmonoamide disodium (i) sulfosuccinate and 24.0 parts of polyoxyethylene alkyl ether sulfosuccinate disodium salt (iii)-<1>, which had been pre-prepared as a 20% aqueous solution, to 80.0 parts of Newcol 707SF, which had been pre-prepared as a 20% aqueous solution, and the second charge was changed Except for replacing 100.0 parts of N-alkylmonoamide disodium sulfosuccinate (i), which has been prepared as a 20% aqueous solution, and 36.0 parts of polyoxyethylene alkyl ether sulfosuccinate disodium salt (iii)-<1> with 120.0 parts of Newcol 707SF, which has been prepared in advance as a 20% aqueous solution, the same procedure as in Example 10 was carried out to obtain an acrylic emulsion (resin composition 11) with a non-volatile content of 52.2%, an average particle size of 205 nm, and a weight-average molecular weight of 47,000.
(Comparative Example 2)
In the deionized water charge in the polymerization reactor of Example 11, the amount was changed from 285.0 parts to 270.0 parts, and in the monomer emulsion charge, the first charge was changed from 50.0 parts of N-alkylmonoamide disodium (i) sulfosuccinate and 24.0 parts of polyoxyethylene alkyl ether sulfosuccinate disodium salt (iii)-<1>, which had been pre-prepared as a 20% aqueous solution, to 80.0 parts of Revenol WX, which had been pre-prepared as a 20% aqueous solution, and the second charge was changed Except for replacing 75.0 parts of N-alkylmonoamide disodium sulfosuccinate (i), which has been prepared as a 20% aqueous solution, and 36.0 parts of polyoxyethylene alkyl ether sulfosuccinate disodium salt (iii)-<1> with 120.0 parts of Revenol WX, which has been prepared in advance as a 20% aqueous solution, the same procedure as in Example 11 was carried out to obtain an acrylic emulsion (resin composition 12) with a non-volatile content of 53.3%, an average particle size of 140 nm, and a weight-average molecular weight of 45,000.

(Comparative Example 3)
As an example of comparing sound absorption characteristics, a sample was obtained by cutting glass wool (product name: Glasslon Wool GW32, manufactured by Asahi Fiber Glass Co., Ltd.) into pieces with a diameter of 40 mm and a thickness of 4 mm.
Sound absorption coefficient measurement samples were prepared using resin compositions 1 to 12 from Examples 1 to 10 and Comparative Examples 1 and 2. The evaluation results, along with the measurement data described in Comparative Example 3, are shown in Tables 1, 2, and 3.
The numbers in parentheses in the table represent the amount of each compound (each emulsifier) added.

Claims (11)

This is a sound-absorbing material for electric vehicles obtained using a sound-absorbing composition containing a compound having a sulfosuccinic acid (salt) skeleton and a foaming agent , and a sound-absorbing coating containing inorganic particles.
A sound-absorbing material in which the foam has a density of 0.5 g/cm³ ^or more and 1.5 g/cm³ ^or less . The sound- absorbing material according to claim 1, wherein the sound-absorbing material composition comprises a polymer . The sound- absorbing material according to claim 1 or 2, wherein the content of a compound having a sulfosuccinic acid (salt) skeleton per 100 parts by mass of nonvolatile content of the sound-absorbing material composition is 1 part by mass or more and 10 parts by mass or less. The sound-absorbing material according to any one of claims 1 to 3, wherein the non-volatile content of the sound-absorbing material composition is 40% by mass or more and 70% by mass or less. The sound-absorbing material according to any one of claims 2 to 4, wherein the polymer is emulsion particles. The sound-absorbing material according to claim 5, wherein the emulsion particles have a core-shell composite structure. The sound-absorbing material according to claim 6, wherein the glass transition temperature of the polymer chain of the shell portion is -30 to 30°C. The sound-absorbing material according to any one of claims 1 to 7, wherein the amount of foaming agent per 100 parts by mass of nonvolatile content of the sound-absorbing material composition is 2 parts by mass or less. The sound-absorbing material according to any one of claims 1 to 8 , wherein the sound absorption coefficient measured by the normal incidence sound absorption coefficient measurement method in accordance with JIS A 1405-2 has a peak of 0.5 or more in the 3000 Hz to 5000 Hz range. A method for producing sound-absorbing material for electric vehicles , obtained by foaming a sound-absorbing material composition containing a compound having a sulfosuccinic acid (salt) skeleton and a foaming agent , and a sound-absorbing material coating containing inorganic particles .
A method for manufacturing a sound-absorbing material, wherein the density of the foam of the sound-absorbing material is 0.5 g/cm³ ^or more and 1.5 g/cm³ ^or less. This is a sound absorption method in which a coating film formed from a composition containing a compound having a sulfosuccinic acid (salt) skeleton , a foaming agent, and inorganic particles absorbs sound containing components within the frequency range of 3000 Hz to 5000 Hz.
A sound absorption method wherein the coating film is a foam, and the density of the foam is 0.5 g/cm³ ^or more and 1.5 g/cm³ ^or less.