Resin composition for damping material

Abstract

The purpose of the present invention is to provide a resin composition which is for a damping material and has excellent low-temperature drying properties and coating film stability. The present invention pertains to a resin composition for a damping material, the resin composition containing polymer emulsion particles and having multiple peaks in a particle size distribution measured using a dynamic light scattering particle size distribution analyzer.

Description

Resin composition for vibration damping material

[0001] The present invention relates to a resin composition for a vibration damper.The resin composition for a vibration damper of the present invention can be used particularly for vehicles.

[0002] Vibration-damping materials are used to prevent vibrations and noise in various structures to maintain quietness. For example, they are used in underfloor areas of automobile interiors, as well as in railway vehicles, ships, aircraft, electrical equipment, building structures, construction equipment, and the like. Conventionally, molded products, such as plate-shaped molded products and sheet-shaped molded products, made from materials with vibration-absorbing properties have been used as materials for such vibration-damping materials. Recently, from the standpoints of environmental protection and occupational health, the release of volatile organic compounds (VOCs) into the atmosphere from solvent-based resin compositions has become a problem, leading to a shift to water-based resin compositions. For example, Patent Document 1 describes a resin composition for vibration-damping materials, which includes an emulsion obtained by polymerizing monomer components, further comprising a component having a sulfosuccinic acid (salt) skeleton, wherein the content of the component having a sulfosuccinic acid (salt) skeleton is 50% by mass or more per 100% by mass of anionic surfactant in the composition. This resin composition for vibration-damping materials is capable of producing a coating film with excellent appearance and exhibiting remarkably excellent vibration-damping properties over a wide temperature range.

[0003] Japanese Patent Application Laid-Open No. 2017-048364

[0004] However, the dry film-forming properties of aqueous resin compositions depend mainly on the evaporation rate of water, and therefore dry film formation is slower than that of solvent-based paints, and the energy consumption during drying is high. Although the use of aqueous emulsions is preferable from the viewpoint of VOC reduction, aqueous resin compositions that can reduce the energy consumption during drying are desired from the viewpoint of further reducing the environmental load. The present inventors have investigated resin compositions for vibration dampers that can reduce energy consumption while maintaining the performance of the resin composition for vibration dampers, specifically resin compositions that have excellent low-temperature drying properties and coating film stability.

[0005] The present inventors have conducted research in light of the above-mentioned problems and have found that a resin composition for vibration damping materials that contains polymer emulsion particles and has multiple peaks in a particle size distribution (particle diameter distribution) measured using a particle size distribution analyzer based on the dynamic light scattering method has excellent low-temperature drying properties and coating film stability, and have completed the present invention.

[0006] According to the present invention, there is provided a resin composition for vibration damping materials which has excellent low-temperature drying properties and coating film stability.

[0007] <Resin Composition for Vibration Damping Material> The resin composition for vibration damping material of the present disclosure contains polymer emulsion particles. The resin composition for vibration damping material of the present disclosure has multiple peaks in its particle size distribution measured using a particle size distribution analyzer based on dynamic light scattering. The presence of multiple peaks in the particle size distribution is expected to improve low-temperature drying properties and coating film stability. In other words, the number of peaks in the particle size distribution of the resin composition for vibration damping material of the present disclosure (also referred to as the particle size distribution number) may be multiple, and although the upper limit is not particularly limited, it is typically 10 or less, preferably 5 or less, and more preferably 2. The presence of multiple peaks in the particle size distribution improves low-temperature drying properties and coating film stability because the presence of multiple components with different particle sizes changes the particle packing state and reduces the viscosity of the resin composition containing the polymer emulsion particles, thereby maintaining operability when forming a coating film even when the solids concentration of the resin composition is increased, and the moisture content of the resin composition can be reduced, resulting in excellent low-temperature drying properties. Furthermore, the film is formed in a densely packed state, resulting in the formation of a stable coating film that is less likely to crack.

[0008] In the particle size distribution of the resin composition for vibration damping material of the present disclosure, the particle size distribution with the largest peak intensity is defined as the first peak, and the particle size distribution with the next largest peak intensity is defined as the second peak. The particle size distribution of the resin composition for vibration damping material of the present disclosure preferably has a first peak in the range of 300 nm to 800 nm and a second peak in the range of 50 nm to 150 nm. In the particle size distribution of the resin composition for vibration damping material of the present disclosure, the particle size at the apex of the first peak (also referred to as the particle size of the first peak) is preferably in the range of 300 nm to 800 nm. The particle size at the apex of the second peak (also referred to as the particle size of the second peak) is preferably in the range of 50 nm to 150 nm. In the particle size distribution of the polymer emulsion particles of the present disclosure, the intensity ratio (volume ratio) of the first peak having a size in the range of 300 nm or more and 800 nm or less to the second peak having a size in the range of 50 nm or more and 150 nm or less is preferably 10:0.3 to 10:10, more preferably 10:0.5 to 10:7, and even more preferably 10:0.9 to 10:4. The total volume ratio of the peaks below the second peak to the entire particle size distribution of the resin composition for vibration damping materials of the present disclosure is preferably 3 vol% or more, more preferably 5 vol% or more, and even more preferably 8 vol% or more. The total volume ratio of the peaks below the second peak is preferably 50 vol% or less, more preferably 40 vol% or less, and even more preferably 30 vol% or less. In this specification, the peaks equal to or lower than the second peak relative to the entire particle size distribution refer to peaks other than the particle size distribution (first peak) having the largest peak intensity, and the total volume ratio of peaks equal to or lower than the second peak refers to the total volume ratio of particle size distributions other than the first peak (for example, the total volume ratio of particle size distributions having a second peak and a third peak). The method for calculating the intensity ratio (volume ratio) when peaks overlap is as follows. For example, when a first peak overlaps with a second peak whose apex particle size is smaller than that of the first peak, the first peak and the second peak can be identified by calculating the intensity ratio (volume ratio) using the particle size value at the minimum value between the first peak and the second peak as a threshold, and regarding the peak equal to or higher than the threshold as the first peak and the peak equal to or lower than the threshold as the second peak.The resin composition for vibration damping materials having the above particle size distribution can be easily obtained, for example, by adding (post-adding) an emulsifier during the polymerization process, separate from the emulsifier used in the monomer emulsion, as described below. Alternatively, the resin composition can be obtained by mixing two or more types of polymer emulsion particles having different particle size distributions.

[0009] In the particle size distribution of the resin composition for vibration dampers of the present disclosure, it is preferable that the molecular weights of the first peak particles and the second peak particles are uniform. A uniform molecular weight is expected to improve vibration damping properties. A uniform molecular weight of the first peak particles and the second peak particles means that the resin composition for vibration dampers has a narrow molecular weight distribution (Mw / Mn) of 4.5 or less, without multiple peak tops, when measured using a molecular weight measurement method. The molecular weight distribution of the resin composition for vibration dampers of the present disclosure is preferably 3.5 or less, and more preferably 2.5 or less. The reason why vibration damping properties improve when the molecular weights of the first peak particles and the second peak particles are uniform in the particle size distribution is thought to be because the mobility of molecular chains is improved by reducing the amount of high molecular weight components. A resin composition for vibration dampers in which the molecular weights of the first peak particles and the second peak particles are uniform can be easily obtained, for example, by adding (post-adding) a polymerization chain transfer agent during the polymerization process, separate from the polymerization chain transfer agent used in the monomer emulsion, as described below. Alternatively, the emulsion may be obtained by mixing two or more types of polymer emulsion particles having different particle size distributions but uniform molecular weights. The particle size distribution is measured by the method described in the Examples.

[0010] (Polymer emulsion particles) The polymer emulsion particles of the present disclosure include an emulsion obtained by polymerizing a monomer component, and are emulsion particles containing a polymer having structural units derived from the monomer. The structural units derived from the monomer are not limited to structural units formed by polymerizing the monomer, but may also be structural units formed by a post-reaction after polymerization, for example. The polymer of the present disclosure is not particularly limited, but may have a structural unit derived from a carboxylic acid (salt) group-containing monomer. The carboxylic acid (salt) group refers to a carboxylic acid group and / or a carboxylic acid base.

[0011] Salts of structural units derived from the carboxylic acid group-containing monomer of the present disclosure are preferably metal salts, ammonium salts, organic amine salts, etc. Examples of suitable metal atoms forming metal salts include monovalent metal atoms such as alkali metal atoms (e.g., lithium, sodium, potassium); divalent metal atoms (e.g., calcium, magnesium); and trivalent metal atoms (e.g., aluminum, iron). Suitable organic amine salts include alkanolamine salts (e.g., ethanolamine salts, diethanolamine salts, triethanolamine salts), and triethylamine salts. The structural units derived from the carboxylic acid (salt) group-containing monomer of the present disclosure are preferably structural units derived from (meth)acrylic acid monomers. In other words, the polymer emulsion particles of the present disclosure preferably contain a (meth)acrylic polymer. The (meth)acrylic polymer refers to a polymer having structural units derived from (meth)acrylic acid monomers. The (meth)acrylic polymer of the present disclosure preferably contains structural units derived from (meth)acrylic acid monomers and structural units derived from other copolymerizable unsaturated monomers. By including structural units derived from a (meth)acrylic acid monomer, the dispersibility of inorganic pigments and the like is improved in paints containing the resin composition for vibration damping materials of the present invention, resulting in superior coating film functionality. Furthermore, by including other copolymerizable unsaturated monomers, it becomes easier to adjust the acid value, Tg, physical properties, and the like of the polymer. The (meth)acrylic acid monomer of the present disclosure is a monomer having at least one group selected from an acryloyl group, a methacryloyl group, or a group in which a hydrogen atom in these groups has been replaced with another atom or atomic group, and having a carboxyl group (—COOH group) or a salt thereof or an acid anhydride group (—C(═O)—O—C(═O)— group) having a carbonyl group in the group, and is preferably (meth)acrylic acid (salt). The salt of the carboxyl group contained in the (meth)acrylic acid monomer of the present disclosure is preferably a metal salt, an ammonium salt, an organic amine salt, or the like. As for the metal salts and organic amine salts, the same salts as those mentioned above as salts of the monomer unit having a carboxylic acid group can be mentioned.

[0012] Other copolymerizable unsaturated monomers of the present disclosure include (meth)acrylic monomers other than (meth)acrylic acid monomers, unsaturated monomers having an aromatic ring, etc. The (meth)acrylic monomers other than (meth)acrylic acid monomers refer to monomers having an acryloyl group or a methacryloyl group, or a group in which a hydrogen atom in these groups is replaced with another atom or atomic group, and in which the carboxyl group is in an ester form, or derivatives of such monomers.

[0013] Examples of the (meth)acrylic monomer other than the (meth)acrylic acid monomer of the present 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, and pentyl methacrylate. acrylate, 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, tridecyl acrylate 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, and the like; and esters of other (meth)acrylic acid monomers, and it is preferable to use one or more of these.Examples of the unsaturated monomer having an aromatic ring according to the present disclosure include divinylbenzene, styrene, α-methylstyrene, vinyltoluene, and ethylvinylbenzene, with styrene being preferred.

[0014] The content of structural units derived from (meth)acrylic acid monomers in 100 parts by mass of the (meth)acrylic polymer of the present disclosure 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, and particularly preferably 0.7 parts by mass or more. The content of structural units derived from the (meth)acrylic acid monomers is 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. The content of structural units derived from other copolymerizable unsaturated monomers in 100 parts by mass of the (meth)acrylic polymer of the present disclosure is preferably 95 parts by mass or more, more preferably 96 parts by mass or more, and even more preferably 97 parts by mass or more. The content of structural units derived from other copolymerizable unsaturated monomers is preferably 99.9 parts by mass or less, more preferably 99.7 parts by mass or less, even more preferably 99.5 parts by mass or less, and particularly preferably 99.3 parts by mass or less. The content of structural units derived from (meth)acrylic monomers other than (meth)acrylic acid monomers in 100 parts by mass of the (meth)acrylic polymer of the present disclosure is preferably 20 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 60 parts by mass or more. The content of structural units derived from (meth)acrylic monomers other than (meth)acrylic acid monomers is preferably 99.9 parts by mass or less, more preferably 99.7 parts by mass or less, and even more preferably 99.5 parts by mass or less. The content of structural units derived from unsaturated monomers having an aromatic ring in 100 parts by mass of the (meth)acrylic polymer of the present 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, and may be 20 parts by mass or more, or 40 parts by mass or more. The content of structural units derived from unsaturated monomers having an aromatic ring is 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.

[0015] The resin composition for vibration dampers of the present disclosure may contain one type of polymer, or may contain two or more types of polymers. When the resin composition for vibration dampers of the present disclosure contains two or more types of polymer emulsion particles of the present disclosure, it may be a mixture obtained by mixing (blending) two or more types of polymer emulsion particles, or it may be an emulsion in which two or more types of polymer chains are composited, obtained by producing a product containing two or more types of polymer chains in a series of production processes (e.g., multi-stage polymerization, etc.). To obtain a product containing two or more types of polymer emulsion particles in a series of production processes, production conditions such as monomer dropping conditions can be appropriately set. Examples of the composite of two or more types of polymer chains include a form having a core portion and a shell portion, as described below. In other words, the resin composition for vibration dampers of the present disclosure may be a composition containing single-layer polymer emulsion particles consisting only of a core portion, core-shell particles having a core portion and a shell portion, or a mixture obtained by mixing them. Examples of the polymer emulsion particles of the present disclosure having a core portion and a shell portion include those composed of two types of polymers, one of which forms the core portion and the other of which forms the shell portion.

[0016] When the polymer emulsion particles of the present disclosure contain a (meth)acrylic polymer, the (meth)acrylic polymer may be a polymer having a structural unit derived from a (meth)acrylic acid monomer. For example, the (meth)acrylic acid monomer may be contained in either the monomer component forming the core portion of the polymer emulsion particle, the monomer component forming the shell portion, or both. When the polymer emulsion particles of the present disclosure are in the form of a composite of two or more polymer chains, the polymer chains may be completely compatible with each other, forming a homogeneous structure in which they are indistinguishable, or they may be in a heterogeneous structure in which they are not completely compatible with each other (e.g., a core-shell composite structure or a microdomain structure). Among these structures, a core-shell composite structure is preferred in order to fully utilize the properties of the polymer emulsion particles and produce stable polymer emulsion particles. Polymer emulsion particles having a core-shell composite structure have excellent vibration damping properties over a wide range within the practical temperature range. The resin composition exhibits superior vibration-damping properties, particularly in the high-temperature range, compared with other resin compositions for vibration-damping materials, and as a result, can exhibit vibration-damping performance over a wide range of temperatures, from room temperature to high temperatures, within the practical temperature range. In the core-shell composite structure, the surface of the core is preferably covered with the shell. In this case, it is preferable that the surface of the core is completely covered with the shell, but it does not have to be completely covered; for example, it may be covered in a mesh-like pattern, or the core may be exposed in places.

[0017] The polymer emulsion particles of the present disclosure may contain, in addition to the above-described polymer, a compound having a sulfosuccinic acid (salt) skeleton. The compound having a sulfosuccinic acid (salt) skeleton of the present disclosure may be a compound represented by the following general formula (1):

[0018]

[0019] (In the formula, R １ represents a hydrogen atom or a monovalent alkyl group having 1 to 30 carbon atoms. -A- represents -O- or -NH-. R ２represents 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. R ３ represents a hydrogen atom, an alkyl group, a metal salt, an ammonium salt, or an organic amine salt. １ Preferably, R represents a monovalent alkyl group having 1 to 30 carbon atoms. １ The number of carbon atoms in the R is preferably 4 or more, more preferably 8 or more, and even more preferably 12 or more. １ The number of carbon atoms in R is preferably 25 or less, and more preferably 20 or less. The monovalent alkyl group is preferably a primary alkyl group or a secondary alkyl group. ２ is preferably a C2-4 alkylene group such as an ethylene group, a propylene group, or a butylene group, and more preferably an ethylene group. ２ O) ｎ When the moiety is composed of two or more kinds of oxyalkylene groups, the total R ２ It is intended that the amount of the hydroxyl group (R ２ O) ｎ In the region, the above R ２is more preferably composed solely of ethylene groups. In one preferred embodiment of the resin composition for vibration damping materials of the present invention, the average number of added moles n is 3 to 200. From the viewpoint of further enhancing the function of the compound having a sulfosuccinic acid (salt) skeleton as an emulsifier and improving vibration damping, the average number of added moles 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 added moles 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. X and Y may be 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. It is preferred that either X or Y represents a sulfonic acid (salt) group, and the other represents a hydrogen atom. In other words, the polymer emulsion particles of the present disclosure may contain a sulfosuccinic acid half ester (salt) in addition to the above-described polymer.

[0020] The sulfosuccinic acid half ester (salt) of the present disclosure may be a compound represented by the following general formula (2).

[0021]

[0022] (In the formula, R ４ represents a secondary alkyl group having 12 to 14 carbon atoms. ５ represents a hydrogen atom, an alkyl group, a metal salt, an ammonium salt, or an organic amine salt. n represents the average number of moles added. The preferred range of n in the above general formula (2) is the same as the preferred range of the average number of moles added n in the above formula (1). The compound having a sulfosuccinic acid (salt) skeleton of the present disclosure may be used as an emulsifier when producing polymer emulsion particles.

[0023] The polymer emulsion particles of the present disclosure may contain a polyoxyalkylene secondary alkyl ether in addition to the above-described polymer and compound having a sulfosuccinic acid (salt) skeleton. The polyoxyalkylene secondary alkyl ether of the present disclosure may have one or two or more (poly)ethylene glycol chains, but preferably has one (poly)ethylene glycol chain. The polyoxyalkylene secondary alkyl ether of the present disclosure preferably has an organic group having 3 or more carbon atoms. Examples of the organic group having 3 or more carbon atoms include hydrocarbon groups such as alkyl groups, alkenyl groups, and alkynyl groups having 3 or more carbon atoms, and among these, alkyl groups having 3 or more carbon atoms are preferred. The organic group may further have an organic substituent such as an alkoxy group, an aryl group, an alkylsulfonyl group, an arylsulfonyl group, an arylalkylsulfonyl group, a trialkylsilyl group, a dialkylarylsilyl group, an alkyldiarylsilyl group, a triarylsilyl group, a bis(dialkylamino)phosphanyl group, a bis(dialkylamino)phosphinoyl group, a dialkylphosphanyl group, a dialkylphosphinoyl group, a diarylphosphanyl group, or a diarylphosphinoyl group. The organic group (preferably a hydrocarbon group) preferably has 5 or more carbon atoms, more preferably 8 or more, even more preferably 10 or more, and particularly preferably 12 or more. The number of carbon atoms is preferably 30 or less, more preferably 24 or less, even more preferably 18 or less, and particularly preferably 14 or less. The polyoxyalkylene secondary alkyl ether of the present disclosure may be a compound represented by the following general formula (3):

[0024]

[0025] (wherein m and n are each an integer of 0 or more, and x represents the average number of moles of ethylene oxide added and is a number from 3 to 200). In the general formula (3), m and n are each preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and particularly preferably 4 or more. The preferred range of m+n in the general formula (3) is ３ - (CH ２ ) ｍ -CH-(CH ２ ) ｎ -CH ３ The total carbon number of the above may be set so as to fall within the preferred range of the carbon number of the organic group described above, preferably 2 or more, more preferably 5 or more, even more preferably 7 or more, and particularly preferably 9 or more. The carbon number is preferably 27 or less, more preferably 21 or less, even more preferably 15 or less, and particularly preferably 11 or less. The preferred range for x in the above general formula (3) is the same as the preferred range for the average number of moles of ethylene oxide added, n, constituting the (poly)ethylene glycol chain described above. The polyoxyalkylene secondary alkyl ether of the present disclosure can be obtained using a conventionally known method, such as adding ethylene oxide to a hydroxyl group possessed by a secondary alcohol. Furthermore, commercially available products can also be used as the compound according to the present invention. Examples of commercially available products include the Softanol M series, such as Softanol 90, Softanol 120, Softanol 200, and Softanol 400, and the Softanol L series, such as Softanol L90 (each manufactured by Nippon Shokubai Co., Ltd.). The polyoxyalkylene secondary alkyl ethers of the present disclosure may be used as emulsifiers in producing polymer emulsion particles.

[0026] The glass transition temperature of the polymer emulsion particles of the present disclosure is preferably −20° C. or higher, more preferably −15° C. or higher, and even more preferably −10° C. or higher. The glass transition temperature is 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 emulsion particles of the present disclosure refers to the glass transition temperature of the polymer forming the polymer emulsion particles. The glass transition temperature (Tg) can be calculated by the method described in the Examples below. Furthermore, when at least one type of emulsion according to the present disclosure is obtained by multistage polymerization (for example, when the polymer emulsion particles have a core portion and a shell portion), the glass transition temperature refers to the Tg (total Tg) calculated from the monomer composition used in all stages. When at least one type of polymer emulsion particle of the present disclosure is in the form of a composite of two or more types of polymer chains, the glass transition temperature of one of the polymer chains (for example, the polymer chain of the core portion) is preferably 0° C. or higher, and more preferably 10° C. or higher. The glass transition temperature of one polymer chain is preferably 60°C or lower, more preferably 50°C or lower. The glass transition temperature of the other polymer chain (e.g., the polymer chain of the shell portion) is preferably -30°C or higher, more preferably -20°C or higher. The glass transition temperature of the other polymer chain is preferably 30°C or lower, more preferably 20°C or lower. The difference in glass transition temperature between one polymer chain and the other polymer chain is preferably 5°C or higher, more preferably 10°C or higher, and even more preferably 20°C or higher. The difference in glass transition temperature is preferably 60°C or lower, more preferably 50°C or lower, and even more preferably 40°C or lower. By providing such a difference in glass transition temperature, it can be expected that, for example, when applied to vibration damping material applications, higher vibration damping properties can be exhibited over a wide temperature range, and it can be expected that vibration damping properties will be further improved in particular in the practical range of 20 to 60°C.

[0027] The weight average molecular weight of the polymer emulsion particles of the present disclosure is preferably 18,000 or more, more preferably 20,000 or more, even more preferably 22,000 or more, and particularly preferably 24,000 or more. The weight average molecular weight is preferably 300,000 or less, more preferably 200,000 or less, and even more preferably 100,000 or less. The weight average molecular weight of the polymer emulsion particles refers to the weight average molecular weight of the polymer forming the polymer emulsion particles. The weight average molecular weight (Mw) can be measured using GPC under the conditions described in the Examples below. The average particle diameter of the polymer emulsion particles of the present disclosure is preferably 80 nm or more, more preferably 100 nm or more. The average particle diameter is preferably 450 nm or less, more preferably 400 nm or less, and even more preferably 350 nm or less. The average particle diameter of the polymer emulsion particles can be measured by the method described in the Examples below. By using polymer emulsion particles having an average particle size within this range, it is expected that the basic performance requirements for a vibration damping material, such as coating appearance and coatability, will be satisfied, and vibration damping properties will be further improved. The minimum film-forming temperature of the polymer emulsion particles of the present disclosure is preferably 0°C or higher, and more preferably 5°C or higher. The minimum film-forming temperature is preferably 40°C or lower, more preferably 35°C or lower, and even more preferably 30°C or lower. From the viewpoints of vibration damping design within the practical temperature range for vibration damping material applications and improving film-forming properties during low-temperature drying, the polymer emulsion particles of the present disclosure preferably have a difference between the glass transition temperature of the polymer emulsion particles and the minimum film-forming temperature of the polymer emulsion particles (|(glass transition temperature of polymer emulsion particles) - (minimum film-forming temperature of polymer emulsion particles)|) of 9°C or lower, more preferably 7°C or lower, and even more preferably 5°C or lower. The minimum film-forming temperature of the polymer emulsion particles is measured by the method described in the examples. The polymer emulsion particles of the present disclosure are preferably dispersed in a solvent, and more preferably dispersed in an aqueous solvent from the viewpoint of improving the working environment. Dispersed in a solvent means dispersed without dissolving in the solvent. The aqueous solvent of the present disclosure may contain other organic solvents as long as it contains water, but is preferably water.The content of water in 100 parts by mass of the aqueous solvent 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 be 100 parts by mass.

[0028] The nonvolatile content (nonvolatile content) of the resin composition for vibration damping material of the present disclosure is preferably 55.0% by mass or more, more preferably 57% by mass or more, and even more preferably 60% by mass or more, relative to the resin composition for vibration damping material. The nonvolatile content is preferably 80% by mass or less, and may be 70% by mass or less. The nonvolatile content referred to here can be measured using a known method. For example, after weighing about 1 g of the resin composition for vibration damping material and drying it in a hot air dryer at 150°C for 1 hour, the dry residue can be taken as the nonvolatile content and the ratio to the mass before drying can be calculated as % by mass. The content of the compound having a sulfosuccinic acid (salt) skeleton per 100 parts by mass of the nonvolatile content of the resin composition for vibration damping material of the present disclosure 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, and particularly preferably 1 part by mass or more. The content of the compound having a sulfosuccinic acid (salt) skeleton is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less. The content of the sulfosuccinic acid half ester (salt) per 100 parts by mass of the non-volatile content of the resin composition for vibration damping material of the present disclosure 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, and particularly preferably 1 part by mass or more. The content of the sulfosuccinic acid half ester (salt) is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less. The content of the polyoxyalkylene secondary alkyl ether per 100 parts by mass of the non-volatile content of the resin composition for vibration damping material of the present disclosure is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 2 parts by mass or more. The content of the polyoxyalkylene secondary alkyl ether is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less.

[0029] The viscosity of the resin composition for vibration damping materials of the present disclosure is preferably 10 mPa·s or more, more preferably 30 mPa·s or more, and even more preferably 50 mPa·s or more. The viscosity is preferably 5000 mPa·s or less, more preferably 3500 mPa·s or less, and even more preferably 2000 mPa·s or less. The viscosity of the resin composition for vibration damping materials referred to here is measured using a B-type rotational viscometer under conditions of 25°C and 20 rpm.

[0030] <Method for Producing a Resin Composition for a Vibration Damping Material> The method for producing the resin composition for a vibration damping material of the present disclosure is not particularly limited, but is preferably produced by emulsion polymerization using an emulsifier. Methods other than emulsion polymerization, such as forming polymer emulsion particles by the action of an emulsifier on a polymer polymerized by suspension polymerization, may also be used. The method for producing a resin composition for a vibration damping material of the present disclosure preferably includes, for example, a polymerization step, which preferably includes a step of adding an emulsifier to a reaction liquid derived from a monomer emulsion. In other words, the method for producing a resin composition for a vibration damping material of the present disclosure may include a polymerization step of emulsion polymerization using a monomer emulsion containing a monomer component and an emulsifier, which polymerization step may include a step of adding an emulsifier to a polymerization reaction liquid containing unreacted monomer components and an emulsifier. By providing new micelles (reaction fields for emulsion polymerization formed by the emulsifier) ​​to the unreacted monomer component, a second peak component can be generated during polymerization. Since unreacted monomer components are essential, an emulsifier is added to the polymerization reaction solution during the polymerization step in which a sufficient amount of unreacted monomer components remain in the polymerization reaction solution. The emulsion polymerization method of the present disclosure is not particularly limited, and can be carried out, for example, by appropriately adding monomer components and a polymerization initiator to an aqueous medium in the presence of an emulsifier and / or a protective colloid and then polymerizing the monomer components. It is also preferable to use a polymerization chain transfer agent or the like for molecular weight control. For example, the polymerization step preferably includes a step of adding a polymerization chain transfer agent to a reaction solution derived from a monomer emulsion. In other words, the polymerization step preferably includes a step of adding a polymerization chain transfer agent to a polymerization reaction solution containing unreacted monomer components and an emulsifier. When the polymer contained in the polymer emulsion particles has a core portion and a shell portion, it is preferable to obtain the polymer emulsion particles by multi-stage polymerization, in which a core portion is formed by emulsion-polymerizing a monomer component in an aqueous medium in the presence of an emulsifier and / or a protective colloid, and then a further monomer component is emulsion-polymerized to the emulsion containing the core portion to form the shell portion. Examples of the emulsifier of the present disclosure include anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, amphoteric emulsifiers, and polymeric emulsifiers, and one or more of these may be used.

[0031] The anionic emulsifier of the present disclosure is not particularly limited, and it is preferable to use the above-mentioned compound having a sulfosuccinic acid (salt) skeleton. Examples of anionic emulsifiers other than compounds having a sulfosuccinic acid (salt) skeleton include polyoxyalkylene alkyl ether sulfate salts, polyoxyalkylene oleyl ether sodium sulfate salts, polyoxyalkylene alkyl phenyl ether sulfate salts, alkyl diphenyl ether disulfonates, polyoxyalkylene (mono-, di-, tri-) styryl phenyl ether sulfate salts, polyoxyalkylene (mono-, di-, tri-) benzyl phenyl ether sulfate salts, sodium dodecyl polyglycol ether sulfate, Examples of suitable emulsifiers include alkyl sulfonates such as sodium sulforisinoate, sulfonated paraffin salts, alkyl sulfonates such as sodium dodecylbenzenesulfonate and alkali metal sulfates of alkali phenol hydroxyethylene, high alkyl naphthalene sulfonates, naphthalene sulfonic acid formalin condensates, fatty acid salts such as sodium laurate, triethanolamine oleate, and triethanolamine abietate, polyoxyalkyl ether sulfates, polyoxyethylene carboxylic acid ester sulfates, polyoxyethylene phenyl ether sulfates, and polyoxyethylene alkylaryl sulfate salts. One or more of these may be used. The content of the compound having a sulfosuccinic acid (salt) skeleton per 100 parts by mass of the anionic emulsifier of the present disclosure is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and even more preferably 95 parts by mass or more, and may even be 100 parts by mass.

[0032] The nonionic emulsifier of the present disclosure is not particularly limited, and it is preferable to use the above-mentioned polyoxyalkylene secondary alkyl ether. Examples of nonionic emulsifiers other than polyoxyalkylene secondary alkyl ethers include polyoxyethylene alkyl ethers; polyoxyethylene alkylaryl ethers; sorbitan aliphatic esters; polyoxyethylene sorbitan aliphatic esters; aliphatic monoglycerides such as glycerol monolaurate; polyoxyethylene oxypropylene copolymers; condensation products of ethylene oxide with aliphatic amines, amides, or acids. The content of the polyoxyalkylene secondary alkyl ether per 100 parts by mass of the nonionic emulsifier of the present disclosure is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and even more preferably 95 parts by mass or more, and may be 100 parts by mass.

[0033] The cationic emulsifier of the present disclosure is not particularly limited, and examples thereof include dialkyldimethylammonium salts, ester-type dialkylammonium salts, amide-type dialkylammonium salts, and dialkylimidazolinium salts, and one or more of these can be used.

[0034] The amphoteric emulsifier of the present disclosure is not particularly limited, and examples thereof include alkyldimethylaminoacetic acid betaine, alkyldimethylamine oxide, alkylcarboxymethylhydroxyethylimidazolinium betaine, alkylamidopropyl betaine, and alkylhydroxysulfobetaine, and one or more of these may be used.

[0035] The polymer emulsifier of the present disclosure is not particularly limited, and examples thereof include polyvinyl alcohol and modified products thereof; (meth)acrylic water-soluble polymers; hydroxyethyl(meth)acrylic water-soluble polymers; hydroxypropyl(meth)acrylic water-soluble polymers; polyvinylpyrrolidone; and the like, and one or more of these may be used.

[0036] The polymerization initiator of the present disclosure is not particularly limited as long as it is a substance that decomposes when heated to generate radical molecules, but water-soluble initiators are preferably used. Examples include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate; water-soluble azo compounds such as 2,2'-azobis(2-amidinopropane) dihydrochloride and 4,4'-azobis(4-cyanopentanoic acid); thermal decomposition initiators such as hydrogen peroxide; and redox polymerization initiators such as hydrogen peroxide and ascorbic acid, t-butyl hydroperoxide and Rongalite, potassium persulfate and a metal salt, and ammonium persulfate and sodium bisulfite. One or more of these may be used. The amount of the polymerization initiator of the present disclosure is not particularly limited and may be set appropriately depending on the type of polymerization initiator, etc. However, for example, it is preferably 0.1 to 2 parts by mass, more preferably 0.2 to 1 part by mass, per 100 parts by mass of the total amount of the monomer components used to form the polymer.

[0037] The polymerization initiator of the present disclosure can be used in combination with a reducing agent, if necessary, to promote emulsion polymerization. Examples of reducing agents include reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, and glucose; and reducing inorganic compounds such as sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium metabisulfite, sodium hydrogensulfite, and thiourea dioxide, and one or more of these can be used. The amount of the reducing agent of the present disclosure to be used is not particularly limited, and is preferably, for example, 0.05 to 1 part by mass per 100 parts by mass of the total amount of the monomer components used to form the polymer.

[0038] When a resin composition for vibration damping materials is prepared, the blending ratio of the polymerization initiator and the reducing agent (polymerization initiator / reducing agent) of the present disclosure is preferably 1.0 to 2.0 in molar ratio, and more preferably 1.2 to 1.9, from the viewpoint of preventing decomposition of the isothiazolinone compound, which is a surface modifier.

[0039] The polymerization chain transfer agent of the present disclosure is not particularly limited, and examples thereof include alkyl mercaptans such as hexyl mercaptan, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, and n-tetradecyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, carbon tetrabromide, and ethylene bromide; mercaptocarboxylic acid alkyl esters such as 2-ethylhexyl mercaptoacetate, 2-ethylhexyl mercaptopropionate, and tridecyl mercaptopropionate; mercaptocarboxylic acid alkoxyalkyl esters such as methoxybutyl mercaptoacetate and methoxybutyl mercaptopropionate; carboxylic acid mercaptoalkyl esters such as 2-mercaptoethyl octanoate, α-methylstyrene dimer, terpinolene, α-terpinene, γ-terpinene, dipentene, anisole, and allyl alcohol. These may be used alone or in combination of two or more. Among these, it is preferable to use alkyl mercaptans such as hexyl mercaptan, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan, etc. The amount of the polymerization chain transfer agent of the present disclosure to be used is, for example, preferably 0.1 to 1.0% by mass, more preferably 0.3 to 0.8% by mass, relative to 100% by mass of all monomer components.

[0040] Regarding the polymerization conditions such as emulsion polymerization conditions in the method for producing a resin composition for vibration damping materials according to the present disclosure, the polymerization temperature is not particularly limited and is, for example, preferably 0 to 100° C., more preferably 40 to 95° C. The polymerization time is also not particularly limited and is, for example, preferably 1 to 15 hours, more preferably 5 to 10 hours.

[0041] The method of adding the monomer components, polymerization initiator, etc. of the present disclosure is not particularly limited, and may be, for example, a batch addition method, a continuous addition method, a multi-stage addition method, etc. Furthermore, these addition methods may be appropriately combined.

[0042] The emulsion polymerization conditions in the method for producing a resin composition for vibration damping materials of the present disclosure may include a polymerization step of polymerizing a monomer component. The polymerization step of the present disclosure may include an initial polymerization step, a dropping step, and an aging step after the dropping step. The initial polymerization step of the present disclosure refers to the first step when the emulsion polymerization method is broadly divided into three steps: the initial polymerization step, the dropping step, and the aging step. It refers to a step in which polymerization is carried out for a certain period of time using a monomer emulsion containing a solvent, an emulsifier, and a monomer component. The composition of the monomer component in the initial polymerization step of the present disclosure may be any composition, but may be close to the monomer component in the dropping step.

[0043] The monomer emulsion used in the polymerization step of the present disclosure may be added separately, or a monomer emulsion (also referred to as a pre-emulsion) containing a solvent, an emulsifier, and a monomer component may be prepared and used. The polymerization step in the method for producing a resin composition for vibration dampers of the present disclosure may include an initial polymerization step in which a portion of the monomer emulsion is charged into a reaction vessel and then emulsion-polymerized; a dropping step in which the remaining monomer emulsion is dropped into the polymerization reaction solution; and an aging step in which heating is performed for a certain period of time after the dropping of the monomer emulsion is completed. The method for producing a resin composition for vibration dampers of the present disclosure preferably includes a step of adding an emulsifier separate from the emulsifier used in the monomer emulsion. This step is expected to facilitate the production of a resin composition for vibration dampers with multiple peaks. The step of adding an emulsifier separate from the emulsifier used in the monomer emulsion is also referred to as a post-emulsifier addition step.

[0044] The polymerization step of the present disclosure preferably further includes a step of adding a polymerization chain transfer agent, and more preferably includes, for example, a step of adding the polymerization chain transfer agent simultaneously with the step of post-adding the emulsifier. By including such a step, it is expected that the molecular weight of particles having multiple peaks will be uniform.

[0045] In this specification, the emulsifier used in the monomer emulsion is referred to as emulsifier A, and the emulsifier added separately from emulsifier A is referred to as emulsifier B. The emulsifiers described above can be used as emulsifier A in the present disclosure. The emulsifiers described above can be used as emulsifier B in the present disclosure, but anionic emulsifiers are preferred, compounds having a sulfosuccinic acid (salt) skeleton are more preferred, and sulfosuccinic acid half esters (salts) are even more preferred. In the method for producing a resin composition for vibration damping materials of the present disclosure, emulsifier B may be added during or after the completion of the dropwise addition of the monomer emulsion, but is preferably added after the completion of the dropwise addition. Emulsifier B may be added once or multiple times. When emulsifier B is added during the dropwise addition of the monomer emulsion, it is preferably added after the polymerization rate of the monomer emulsion exceeds 45%, more preferably after it exceeds 50%. The upper limit of the polymerization rate may be 90% or 85%. When emulsifier B is added during the dropwise addition of the monomer emulsion, it is preferably added over a dropwise addition time of 50% or more, more preferably 60% or more, and may even be added over a dropwise addition time of 80% or more, or 90% or more, of the total dropwise addition time of the monomer emulsion. When emulsifier B is added after the end of dropwise addition of the monomer emulsion, it is preferably added within 30 minutes, more preferably within 20 minutes, and even more preferably within 10 minutes after the end of dropwise addition. In the method for producing a resin composition for vibration damping materials of the present disclosure, the mass ratio of emulsifier A to emulsifier B (mass of emulsifier A / mass of emulsifier B) is preferably 4.0 / 1.0 to 0.5 / 1.0, more preferably 3.0 / 1.0 to 0.6 / 1.0, and even more preferably 2.0 / 1.0 to 0.8 / 1.0.

[0046] In this specification, the polymerization chain transfer agent used in the monomer emulsion will be referred to as polymerization chain transfer agent A, and the polymerization chain transfer agent added separately from polymerization chain transfer agent A will be referred to as polymerization chain transfer agent B. The preferred timing, number of additions, and addition time of polymerization chain transfer agent B are the same as the preferred timing, number of additions, and addition time of emulsifier B described above. In the method for producing a resin composition for vibration damping materials according to the present disclosure, the mass ratio of polymerization chain transfer agent A to polymerization chain transfer agent B (mass of polymerization chain transfer agent A / mass of polymerization chain transfer agent B) is preferably 20.0 / 1.0 to 1.0 / 1.0, more preferably 10.0 / 1.0 to 1.5 / 1.0, and even more preferably 5.0 / 1.0 to 2.0 / 1.0.

[0047] In the method for producing a resin composition for vibration damping materials according to the present disclosure, it is preferable to produce an emulsion by emulsion polymerization and then neutralize the emulsion with a neutralizing agent. This stabilizes the emulsion. The neutralizing agent according to the present disclosure is not particularly limited, but it is preferable to use a volatile base that volatilizes when the coating film is heated, as this improves the water resistance and other properties of the coating film formed from the resin composition for vibration damping materials that essentially contains a (meth)acrylic polymer emulsion. More preferably, an amine with a boiling point of 80 to 360°C is used, as this improves the heat drying properties and improves the vibration damping properties. Suitable examples of such neutralizing agents include tertiary amines such as triethanolamine, 2-methylaminoethanol, dimethylethanolamine, diethylethanolamine, and morpholine, as well as diglycolamine. More preferably, an amine with a boiling point of 130 to 280°C is used. The above boiling points are those at atmospheric pressure.

[0048] <Paint for Vibration Damping Material> The resin composition for vibration damping material of the present disclosure can be used to form a paint for vibration damping material by adding other components. A paint for vibration damping material that essentially contains the resin composition for vibration damping material exhibits excellent vibration damping properties and can form a vibration damping material having a coating film with excellent coating film strength. The paint for vibration damping material of the present disclosure refers to a paint that contains at least the resin composition for vibration damping material of the present invention and a filler. Examples of fillers of the present disclosure include inorganic fillers such as calcium carbonate, kaolin, silica, talc, barium sulfate, alumina, iron oxide, titanium oxide, glass stearate, magnesium carbonate, aluminum hydroxide, diatomaceous earth, and clay; scaly inorganic fillers such as glass flakes and mica; and fibrous inorganic fillers such as metal oxide whiskers and glass fibers. When a particulate filler is used as the filler of the present disclosure, the average particle diameter of the filler is preferably 0.5 to 50 μm, more preferably 2 to 25 μm. Examples of particulate fillers include calcium carbonate and titanium oxide. The coating material for vibration dampers of the present disclosure may contain components other than the filler. Examples of other components contained in the coating material for vibration dampers of the present disclosure include foaming agents, pigments, thickeners, solvents, aqueous crosslinking agents, gelling agents, dispersants, antifoaming agents, colorants, anti-rust pigments, plasticizers, stabilizers, wetting agents, preservatives, antifoaming agents, antioxidants, antifungal agents, ultraviolet absorbers, and antistatic agents, and one or more of these can be used.

[0049] Other components of the present disclosure can be mixed with the resin composition for vibration damping materials, etc., using, for example, a butterfly mixer, planetary mixer, spiral mixer, kneader, dissolver, etc. Suitable foaming agents of the present disclosure include, for example, thermally expandable capsules encapsulating low-boiling-point hydrocarbons, organic foaming agents, inorganic foaming agents, etc., and one or more of these can be used. Examples of thermally expandable capsules include Matsumoto Microsphere F-30 and F-50 (manufactured by Matsumoto Oil & Fat Co., Ltd.); Expancel WU642, WU551, WU461, DU551, and DU401 (manufactured by Nippon Expancel Co., Ltd.), etc. Examples of organic foaming agents include azodicarbonamide, azobisisobutyronitrile, N,N-dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazine, and p-oxybis(benzenesulfohydrazide), etc. Examples of inorganic foaming agents include sodium bicarbonate, ammonium carbonate, and silicon hydride, etc. Examples of the thickener of the present disclosure include polyvinyl alcohol, cellulose derivatives, polycarboxylic acid resins, etc. Examples of the solvent of the present disclosure include ethylene glycol, butyl cellosolve, butyl carbitol, butyl carbitol acetate, water, etc. The amount of the solvent may be appropriately set so that the nonvolatile content of the resin composition for vibration damping in the coating material for vibration damping falls within the above-mentioned range. Suitable examples of the aqueous crosslinking agent of the present disclosure include oxazoline compounds such as EPOCROS WS-500, WS-700, K-2010, 2020, and 2030 (all trade names, manufactured by Nippon Shokubai Co., Ltd.); epoxy compounds such as ADEKA RESIN EMN-26-60 and EM-101-50 (all trade names, manufactured by ADEKA Corporation); melamine compounds such as Cymel C-325 (trade name, manufactured by Mitsui Cytec Co., Ltd.); blocked isocyanate compounds; and zinc oxide compounds such as AZO-50 (trade name, 50% by mass zinc oxide aqueous dispersion, manufactured by Nippon Shokubai Co., Ltd.). Examples of the gelling agent of the present disclosure include starch and agar. Examples of the dispersing agent of the present disclosure include inorganic dispersing agents such as sodium hexametaphosphate and sodium tripolyphosphate, and organic dispersing agents such as polycarboxylic acid-based dispersing agents. Examples of the defoaming agent of the present disclosure include silicon-based defoaming agents.Examples of colorants of the present disclosure include organic or inorganic colorants such as carbon black, red iron oxide, Hansa Yellow, Benzene Yellow, Phthalocyanine Blue, and Quinacridone Red. Examples of anti-rust pigments of the present disclosure include metal phosphates, metal molybdates, and metal borates. A polyvalent metal compound may also be used as another component of the present disclosure. In this case, the polyvalent metal compound improves the stability, dispersibility, and heat drying properties of the vibration-damping paint, as well as the vibration-damping properties of the vibration-damping material formed from the vibration-damping paint. The polyvalent metal compound is not particularly limited, and examples include zinc chloride and zinc sulfate. One or more of these may be used.

[0050] The nonvolatile content of the paint for vibration damping material of the present disclosure is, for example, preferably 55% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 75% by mass or more. The nonvolatile content is preferably 92% by mass or less, and may be 87% by mass or less. The blending amount of the resin composition for vibration damping material in the paint for vibration damping material of the present disclosure is, for example, preferably set so that the nonvolatile content of the resin composition for vibration damping material is 10 to 60% by mass, more preferably 15 to 60% by mass, relative to 100% by mass of the nonvolatile content of the paint for vibration damping material.

[0051] The pH of the coating material for vibration damping materials of the present disclosure is preferably 7 to 11, and more preferably 7 to 9. The pH can be measured at 25°C using a pH meter ("F-23" manufactured by Horiba, Ltd.).

[0052] The blending amount of the filler of the present disclosure is preferably 50 to 700 mass %, more preferably 100 to 550 mass %, relative to 100 mass % of the nonvolatile content of the resin composition for vibration damping materials.

[0053] The blending amount of the foaming agent of the present disclosure is preferably 0.4 to 8.0 mass%, more preferably 0.6 to 7.0 mass%, even more preferably 0.8 to 6.0 mass%, and particularly preferably 1.0 to 5.0 mass%, relative to 100 mass% of the nonvolatile content of the resin composition for vibration damping materials, so that the coating film of the vibration damping material satisfies the above-mentioned cross-sectional porosity.

[0054] The blending amount of the thickener of the present disclosure is preferably 0.01 to 2 mass% in terms of nonvolatile content relative to 100 mass% of the nonvolatile content of the resin composition for vibration damping materials, more preferably 0.05 to 1.5 mass%, and even more preferably 0.1 to 1 mass%.

[0055] The blending amount of the aqueous crosslinking agent according to the present disclosure is, for example, preferably 0.01 to 20% by mass, more preferably 0.15 to 15% by mass, and even more preferably 0.5 to 15% by mass in terms of non-volatile content relative to 100% by mass of the non-volatile content of the resin composition for vibration damping materials.

[0056] <Vibration Damping Material> The coating material for vibration damping material of the present disclosure can be applied to a substrate and dried to form a coating film that becomes a vibration damping material. The coating material for vibration damping material can be applied to a substrate using, for example, a brush, a spatula, an air spray, an airless spray, a mortar gun, a lysine gun, or the like.

[0057] The average thickness of the coating film of the vibration-damping material of the present disclosure is preferably 1 to 5 mm. The coating film of the vibration-damping material of the present invention can exhibit excellent vibration-damping properties regardless of the coating film thickness, but from the viewpoint of making the coating film excellent in vibration-damping properties and coating film strength, the average thickness is more preferably 1.5 to 4.5 mm. The average thickness of the coating film of the present disclosure can be determined by measuring the thickness at any 10 points with a vernier caliper and averaging the measurements.

[0058] In addition, the surface density of the coating film after drying is 1.0 to 7.0 kg / m ２ It is also preferable to apply the coating so that the coating amount is 2.0 to 6.0 kg / m. ２ By using the coating material for vibration damping materials of the present invention, it is possible to obtain a coating film that is less likely to expand or crack during and after drying, and is also less likely to slide down on inclined surfaces. The surface density of the coating film of the present disclosure can be calculated from the coating area and the dry weight of the applied coating film.

[0059] After applying the coating material for vibration dampers of the present disclosure, the coating material may be dried to form a coating film by heating or by drying at room temperature, but since the coating material for vibration dampers of the present invention has excellent low-temperature drying properties, the coating material may be dried at 150°C or less, 130°C or less, 120°C or less, or 110°C or less. The coating material may also be dried at 50 to 100°C.

[0060] When the resin composition for vibration damping or the paint for vibration damping of the present disclosure is applied to vibration damping applications, the vibration damping properties can be evaluated by measuring the loss factor of a film formed from the resin composition for vibration damping or the paint for vibration damping. The loss factor of the present disclosure is usually expressed as η and indicates the degree to which vibrations applied to the vibration damping material are attenuated. A higher loss factor indicates better vibration-damping performance. The loss factor of the present disclosure is generally measured by a resonance method, which measures near the resonance frequency, and includes the half-width method, the attenuation rate method, and the mechanical impedance method. In the resin composition for vibration damping or the paint for vibration damping, the loss factor of a film formed from the resin composition for vibration damping or the paint for vibration damping is preferably measured by a resonance method (3 dB method) using a cantilever beam. Measurements using the cantilever beam method can be performed, for example, using a CF-5200 FFT analyzer manufactured by Ono Sokki Co., Ltd. The vibration-damping material of the present disclosure has excellent vibration-damping properties and can be used in a variety of applications. It also has excellent coating strength, with coating peeling and other issues being suppressed, and can be suitably used in applications where coated vibration-damping materials are used, such as automobiles, railway vehicles, ships, aircraft, electrical equipment, building structures, and construction equipment, and can be particularly suitably used in vehicle applications such as automobiles and railways.

[0061] The present invention will be described in more detail below with reference to the following embodiments, but the present invention is not limited to these embodiments. Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass." In the following examples and comparative examples, various resin properties were evaluated as follows:

[0062] <Non-volatile content (N.V.)> Approximately 1 g of the resulting emulsion was weighed and dried in a hot air dryer at 150°C for 1 hour. The remaining amount was taken as the non-volatile content, and the ratio of this to the mass before drying was expressed in mass %. <Viscosity> Measurement was performed using a B-type rotational viscometer (Toki Sangyo Co., Ltd., "VISCOMETER TUB-10") at 25°C and 20 rpm. <Average particle size> The cumulant average particle size of the emulsion particles was measured using a particle size distribution analyzer (Otsuka Electronics Co., Ltd., FPAR-1000) based on the dynamic light scattering method. <Particle size distribution> The particle size distribution (volume %) of the emulsion particles was measured using a particle size distribution analyzer (Beckman Coulter, Inc., LS13320) based on the laser diffraction scattering method, over a particle size range of 0 to 10,000 nm. The number of peaks in the obtained particle size distribution was taken as the particle size distribution number, and the particle size distribution with the largest peak intensity was designated as the first peak, and the particle size distribution with the next largest peak intensity was designated as the second peak, successively. The particle sizes at the apex of each peak in each particle size distribution were designated as the particle size of the first peak and the particle size of the second peak, successively. The total volume ratio (volume %) of the peaks below the second peak to the entire obtained particle size distribution was calculated. <Weight-average molecular weight Mw, number-average molecular weight Mn> Measured by GPC (gel permeation chromatography) under the following measurement conditions. Measurement equipment: HLC-8120GPC (product name, manufactured by Tosoh Corporation); Molecular weight column: TSK-GEL GMHXL-L and TSK-GELG5000HXL (both manufactured by Tosoh Corporation) connected in series; Eluent: Tetrahydrofuran (THF); Calibration curve standard: Polystyrene (manufactured by Tosoh Corporation); Measurement method: The measurement target was dissolved in THF to a solid content of approximately 0.2% by mass, filtered, and used as a measurement sample to measure the molecular weight. <Molecular weight distribution Mw / Mn> The molecular weight distribution Mw / Mn was calculated by dividing the measured weight average molecular weight Mw by the number average molecular weight Mn (weight average molecular weight Mw ÷ number average molecular weight Mn). <Polymer glass transition temperature (Tg)> The Tg of the polymer was calculated using the following calculation formula (1) from the monomer composition used in each stage.

[0063]

[0064] In the formula, Tg' is the Tg (absolute temperature) of the polymer. W1', W2', ... Wn' are the mass fractions of each monomer with respect to all monomer components. T1, T2, ... Tn are the glass transition temperatures (absolute temperatures) of homopolymers (single polymers) composed of each monomer component. The Tg calculated from the monomer compositions used in all stages is described as the "total Tg." The Tg values ​​of each homopolymer used to calculate the glass transition temperature (Tg) of the polymerizable monomer component using the above calculation formula (1) are shown below. Methyl methacrylate (MMA): 105°C Styrene (St): 100°C 2-ethylhexyl acrylate (2EHA): -70°C Butyl acrylate (BA): -56°C Acrylic acid (AA): 95°C <Minimum film-forming temperature> The minimum film-forming temperature of the emulsion was measured by applying the emulsion to a thickness of 0.2 mm on a glass plate placed on a thermal gradient tester (TP-801 LT model manufactured by Tester Sangyo), drying it, and measuring the temperature at which cracks appeared. The surfactants used in the following examples will be described. The sulfosuccinic acid half ester used was a compound represented by the following formula (4) (sulfosuccinic acid half ester (i)).

[0065]

[0066] (In the formula, R ６ represents a secondary alkyl group having 12 to 14 carbon atoms, and n represents the average number of moles added.) As the polyoxyalkylene secondary alkyl ether, a surfactant (secondary alcohol ethoxylate (ii)) manufactured by Nippon Shokubai Co., Ltd., with 20 moles of EO added and 12 to 14 carbon atoms in the alkyl group portion of the secondary alcohol, was used. As the sodium polyoxyethylene alkyl ether sulfate, Levenol WX manufactured by Kao Corporation was used.

[0067] Example 1 235.0 parts of deionized water were charged into a polymerization vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen inlet tube, and a dropping funnel. Thereafter, the internal temperature was raised to 75°C while stirring under a nitrogen gas stream. Meanwhile, the dropping funnel was charged with a monomer emulsion consisting of 565.0 parts of styrene, 420.0 parts of 2-ethylhexyl acrylate, 15.0 parts of acrylic acid, 6.5 parts of t-dodecyl mercaptan (also referred to as t-DM) as a polymerization chain transfer agent, 12.1 parts of sulfosuccinic acid half ester (i) previously prepared as a 50% aqueous solution, 22.5 parts of secondary alcohol ethoxylate (ii) previously prepared as a 20% aqueous solution, and 150.0 parts of deionized water. Next, while maintaining the internal temperature of the polymerization vessel at 75°C, 12.0 parts of the monomer emulsion and 10 parts of a 2.5% aqueous ammonium persulfate solution and 10 parts of a 2% aqueous sodium hydrogen sulfite solution, which served as polymerization initiators (oxidizers), were added to initiate prepolymerization. After 40 minutes, the remaining monomer emulsion was uniformly added dropwise over 300 minutes while maintaining the reaction system at 75°C. At the same time, 70 parts of a 2.5% aqueous ammonium persulfate solution and 30 parts of a 2% aqueous sodium hydrogen sulfite solution were uniformly added dropwise over 300 minutes. After completion of the dropwise addition, 13.2 parts of the sulfosuccinic acid half ester (i), which had been previously adjusted to a 50% aqueous solution, were added to the reaction system. The same temperature was maintained for 120 minutes, and the resulting reaction liquid was cooled to room temperature. Then, 18.6 parts of 2-dimethylethanolamine was added to obtain an acrylic emulsion (resin composition 1 for vibration damping materials) having a glass transition temperature of 3.0°C, a non-volatile content of 64.9%, a viscosity of 541 mPa s, an average particle size of 503 nm, and a weight average molecular weight of 25,000.

[0068] Example 2 The same operation as in Example 1 was carried out, except that in charging the monomer emulsion in Example 1, the amount of styrene was changed from 565.0 parts to 505.0 parts and the amount of 2-ethylhexyl acrylate was changed from 420.0 parts to 480.0 parts, to obtain an acrylic emulsion (resin composition for vibration damping material 2) having a glass transition temperature of −7.0° C., a non-volatile content of 65.0%, a viscosity of 527 mPa s, an average particle size of 508 nm, and a weight average molecular weight of 25,000.

[0069] Example 3 The same operation as in Example 1 was carried out, except that in charging the monomer emulsion in Example 1, the amount of styrene was changed from 565.0 parts to 620.0 parts and the amount of 2-ethylhexyl acrylate was changed from 420.0 parts to 365.0 parts, to obtain an acrylic emulsion (resin composition for vibration damping material 3) having a glass transition temperature of 13.0°C, a non-volatile content of 64.9%, a viscosity of 485 mPa s, an average particle size of 505 nm, and a weight average molecular weight of 25,000.

[0070] Example 4 235.0 parts of deionized water was charged into a polymerization vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen inlet tube, and a dropping funnel. Thereafter, the internal temperature was raised to 75°C while stirring under a nitrogen gas stream. Meanwhile, the dropping funnel was charged with a monomer emulsion consisting of 245.0 parts of styrene, 149.0 parts of 2-ethylhexyl acrylate, 6.0 parts of acrylic acid, 2.6 parts of t-dodecyl mercaptan (also referred to as t-DM) as a polymerization chain transfer agent, 4.8 parts of sulfosuccinic acid half ester (i) previously prepared as a 50% aqueous solution, 9.0 parts of secondary alcohol ethoxylate (ii) previously prepared as a 20% aqueous solution, and 60.0 parts of deionized water. Next, while maintaining the internal temperature of the polymerization vessel at 75°C, 12.0 parts of the monomer emulsion and 10 parts of a 2.5% aqueous ammonium persulfate solution and 10 parts of a 2% aqueous sodium hydrogen sulfite solution, which served as polymerization initiators (oxidizers), were added to initiate prepolymerization. After 40 minutes, the remaining monomer emulsion was uniformly added dropwise over 100 minutes while maintaining the reaction system at 75°C. Simultaneously, 25 parts of a 2.5% aqueous ammonium persulfate solution and 11 parts of a 2% aqueous sodium hydrogen sulfite solution were uniformly added dropwise over 100 minutes, and after the completion of the addition, the same temperature was maintained for 60 minutes, yielding an aqueous dispersion of an acrylic copolymer with a glass transition temperature of 11.3°C that formed the core of the emulsion particles with a multilayer structure. Next, a monomer emulsion consisting of 276.0 parts of styrene as a monomer for forming the shell, 315.0 parts of butyl acrylate, 9.0 parts of acrylic acid, 3.9 parts of t-DM, 7.3 parts of sulfosuccinic acid half ester (i) previously adjusted to a 50% aqueous solution, 13.5 parts of secondary alcohol ethoxylate (ii) previously adjusted to a 20% aqueous solution, and 90.0 parts of deionized water was charged into the dropping funnel, and added dropwise uniformly over 180 minutes to the aqueous dispersion of the acrylic copolymer obtained above. At the same time, 45 parts of a 2.5% aqueous ammonium persulfate solution and 19 parts of a 2% aqueous sodium hydrogen sulfite solution were added dropwise uniformly over 180 minutes. After completion of the dropwise addition, 13.2 parts of sulfosuccinic acid half ester (i) previously adjusted to a 50% aqueous solution was added to the reaction system. The same temperature was then maintained for 120 minutes, and a shell with a glass transition temperature of -2.2 ° C was formed.The resulting reaction liquid was cooled to room temperature, and then 18.6 parts of 2-dimethylethanolamine was added to obtain an acrylic emulsion (resin composition 4 for vibration damping materials) having a glass transition temperature of 3.0°C, a nonvolatile content of 65.2%, a viscosity of 680 mPa s, an average particle size of 510 nm, and a weight average molecular weight of 25,000.

[0071] Example 5 In the charging of the monomer emulsion of Example 1, the amount of styrene was changed from 565.0 parts to 264.5 parts, the amount of 2-ethylhexyl acrylate was changed from 420.0 parts to 228.0 parts, and further 264.5 parts of methyl methacrylate and 228.0 parts of butyl acrylate were added as monomers. The same operations as in Example 1 were carried out except that 13.2 parts of the sulfosuccinic acid half ester (i) added after the completion of dropwise addition was changed to be added 270 minutes after dropwise addition, to obtain an acrylic emulsion (resin composition for vibration damping material 5) having a glass transition temperature of 3.0°C, a non-volatile content of 65.1%, a viscosity of 857 mPa s, an average particle size of 518 nm, and a weight average molecular weight of 25,000.

[0072] Example 6 The same operation as in Example 1 was carried out, except that in charging the monomer emulsion in Example 1, the amount of t-dodecyl mercaptan was changed from 6.5 parts to 2.0 parts, to obtain an acrylic emulsion (resin composition for vibration damping materials 6) having a glass transition temperature of 3.0°C, a non-volatile content of 64.8%, a viscosity of 391 mPa s, an average particle size of 512 nm, and a weight average molecular weight of 200,000.

[0073] Example 7 The same operations as in Example 5 were carried out, except that 13.2 parts of the sulfosuccinic acid half ester (i) was added at 240 minutes after the dropwise addition instead of at 270 minutes after the dropwise addition in Example 5, to obtain an acrylic emulsion (resin composition 7 for vibration damping materials) having a glass transition temperature of 3.0°C, a non-volatile content of 65.1%, a viscosity of 1,308 mPa s, an average particle size of 384 nm, and a weight-average molecular weight of 25,000.

[0074] Example 8 The same operations as in Example 5 were carried out, except that 13.2 parts of the sulfosuccinic acid half ester (i) was added at 195 minutes after the dropwise addition instead of at 270 minutes after the dropwise addition in Example 5, to obtain an acrylic emulsion (resin composition for vibration damping materials 8) having a glass transition temperature of 3.0°C, a non-volatile content of 65.1%, a viscosity of 4,020 mPa s, an average particle size of 262 nm, and a weight average molecular weight of 25,000.

[0075] Example 9 The same operations as in Example 1 were performed, except that the amount of deionized water charged in the polymerization vessel in Example 1 was changed from 235.0 parts to 365.0 parts, to obtain an acrylic emulsion (resin composition for vibration damping materials 9) having a glass transition temperature of 3.0°C, a non-volatile content of 60.0%, a viscosity of 108 mPa s, an average particle size of 507 nm, and a weight average molecular weight of 25,000.

[0076] Example 10 The same operations as in Example 1 were carried out, except that in charging the monomer emulsion in Example 1, the amount of t-dodecyl mercaptan was changed from 6.5 parts to 5.8 parts, and 0.7 parts of t-dodecyl mercaptan was added simultaneously with 13.2 parts of the sulfosuccinic acid half ester (i) added after the completion of dropwise addition, to obtain an acrylic emulsion (resin composition for vibration damping materials 10) having a glass transition temperature of 3.0°C, a nonvolatile content of 65.0%, a viscosity of 498 mPa s, an average particle size of 504 nm, and a weight average molecular weight of 23,000.

[0077] Example 11 The same operation as in Example 10 was carried out, except that in charging the monomer emulsion in Example 10, the amount of t-dodecyl mercaptan was changed from 5.8 parts to 5.0 parts, and the amount of t-dodecyl mercaptan added after the completion of dropwise addition was changed from 0.7 parts to 1.5 parts, to obtain an acrylic emulsion (resin composition for vibration damping materials 11) having a glass transition temperature of 3.0°C, a nonvolatile content of 64.9%, a viscosity of 512 mPa s, an average particle size of 507 nm, and a weight average molecular weight of 21,000.

[0078] Example 12 The same operation as in Example 5 was carried out, except that in charging the monomer emulsion in Example 5, the amount of t-dodecyl mercaptan was changed from 6.5 parts to 5.8 parts, and 0.7 parts of t-dodecyl mercaptan was added simultaneously with 13.2 parts of the sulfosuccinic acid half ester (i) added after the completion of dropwise addition, to obtain an acrylic emulsion (resin composition for vibration damping materials 12) having a glass transition temperature of 3.0°C, a nonvolatile content of 64.9%, a viscosity of 773 mPa s, an average particle size of 521 nm, and a weight average molecular weight of 23,000.

[0079] Comparative Example 1 A polymerization vessel equipped with a stirrer, reflux condenser, thermometer, nitrogen inlet tube, and dropping funnel was charged with 480.0 parts of deionized water. Thereafter, the internal temperature was raised to 75°C while stirring under a nitrogen gas stream. Meanwhile, a monomer emulsion consisting of 565.0 parts of styrene, 420.0 parts of 2-ethylhexyl acrylate, 15.0 parts of acrylic acid, 6.5 parts of t-dodecyl mercaptan (also referred to as t-DM) as a polymerization chain transfer agent, 200.0 parts of polyoxyethylene alkyl ether sodium sulfate (iii) previously adjusted to a 20% aqueous solution, and 190.0 parts of deionized water was charged into the dropping funnel. Next, while maintaining the internal temperature of the polymerization vessel at 75°C, 40.0 parts of the monomer emulsion and 10 parts of a 2.5% aqueous ammonium persulfate solution and 10 parts of a 2% aqueous sodium hydrogen sulfite solution as polymerization initiators (oxidizers) were added to initiate prepolymerization. After 40 minutes, while maintaining the reaction system at 75°C, the remaining monomer emulsion was added dropwise uniformly over 300 minutes. Simultaneously, 70 parts of a 2.5% aqueous ammonium persulfate solution and 30 parts of a 2% aqueous sodium hydrogen sulfite solution were added dropwise uniformly over 300 minutes. After maintaining the same temperature for 120 minutes, the resulting reaction solution was cooled to room temperature, and then 18.6 parts of 2-dimethylethanolamine was added to obtain an acrylic emulsion (comparative resin composition 1) having a glass transition temperature of 3.0°C, a nonvolatile content of 52.0%, a viscosity of 285 mPa s, an average particle size of 150 nm, and a weight-average molecular weight of 25,000.

[0080] Comparative Example 2: The same procedure as in Example 1 was performed, except that the sulfosuccinic acid half ester (i) added after the completion of the dropwise addition in Example 1 was not used. This resulted in an acrylic emulsion (comparative resin composition 2) having a glass transition temperature of 3.0°C, a nonvolatile content of 65.3%, a viscosity of 11,524 mPa·s, an average particle size of 701 nm, and a weight-average molecular weight of 25,000. The compositions and polymer properties of vibration-damping resin compositions 1 to 12 described in Examples 1 to 12 and comparative resin compositions 1 and 2 described in Comparative Examples 1 and 2 are shown in Tables 1 and 2. In Examples 10 to 12, the addition of a chain transfer agent along with the emulsifier resulted in a uniform molecular weight of the polymer. In Tables 1 and 2 below, the particle size distribution number refers to the number of peaks in the particle size distribution of the vibration-damping resin composition measured using a particle size distribution analyzer using the dynamic light scattering method, as described above. The particle size (large particle size fraction) refers to the particle size at the apex of the first peak. Particle size: The small particle size component represents the particle size at the apex of the second peak. The small particle size component ratio represents the total volume ratio of the peaks below the second peak to the entire particle size distribution of the resin composition for vibration damping materials. The degree of arrival during the monomer dropping time represents the timing at which the emulsifier, or the emulsifier and chain transfer agent, are added, expressed as a percentage of the elapsed dropping time relative to the total dropping time of the monomer emulsion.

[0081]

[0082]

[0083] <Preparation of paints for vibration dampers and paints of comparative examples 1 and 2> Paints for vibration dampers 1 to 12 and comparative paints 1 and 2 were prepared using resin compositions for vibration dampers 1 to 12 and comparative resin compositions 1 and 2 by blending as follows, and various properties were evaluated. Resin compositions for vibration dampers 1 to 12, comparative resin compositions 1 and 2: 1000 parts as is Calcium carbonate NN#200 ＊１ 1600 parts Dispersant AQUALIC DL-40S ＊２ 20 parts Thickener Acryset WR-650 ＊３ 25 parts of antifoaming agent Nopco 8034L ＊４ Part 3: Foaming agent F-30 ＊５10 parts <Preparation of Paint of Comparative Example 3> Comparative Resin Composition 1 was blended as follows to prepare Comparative Paint 3 as Comparative Example 3, and various properties were evaluated. Comparative Resin Composition 1 1000 parts as is Calcium carbonate NN#200 ＊１ 2,300 parts Dispersant AQUALIC DL-40S ＊２ 20 parts Thickener Acryset WR-650 ＊３ 25 parts of antifoaming agent Nopco 8034L ＊４ Part 3: Foaming agent F-30 ＊５ 10 parts * 1: Filler manufactured by Nitto Funka Kogyo Co., Ltd. * 2: Polycarboxylic acid type dispersant manufactured by Nippon Shokubai Co., Ltd. (active ingredient 44%) * 3: Alkali-soluble acrylic thickener manufactured by Nippon Shokubai Co., Ltd. (active ingredient 30%) * 4: Antifoaming agent manufactured by San Nopco Ltd. (main component: hydrophobic silicone + mineral oil) * 5: Foaming agent manufactured by Matsumoto Yushi Co., Ltd. <Evaluation of appearance of coating film> [Evaluation of peeling, swelling, and cracking of coating film] The prepared coating was applied to a thickness of 4 mm on a steel plate (product name SPCC-SD, width 75 mm x length 150 mm x thickness 0.8 mm, manufactured by Nippon Test Panel Co., Ltd.). Thereafter, it was dried at 110 ° C. for 30 minutes using a hot air dryer, and the surface condition of the obtained dried coating film was evaluated for peeling, swelling, and the presence or absence of cracking. <Evaluation of Paint Film Solid Content> [Evaluation of Paint Film Low-Temperature Drying Properties] The initial paint solid content was calculated as a theoretical value from the water content of each formulation. The prepared paint was applied to a steel plate (trade name SPCC-SD, width 75 mm x length 150 mm x thickness 0.8 mm, manufactured by Nippon Test Panel Co., Ltd.) to a coating thickness of 4 mm, and dried at 110°C for 30 minutes or at 80°C for 30 minutes, and then left at room temperature for half a day. The coating solid content under each drying condition was calculated from the amount of water loss in the paint film. <Vibration Damping Test> The prepared vibration damping paint was applied to a cold-rolled steel plate (trade name SPCC, width 15 mm x length 250 mm x thickness 1.5 mm, manufactured by Nippon Test Panel Co., Ltd.) to a thickness of 3 mm, pre-dried at 80°C for 30 minutes, and then dried at 150°C for 30 minutes. The cold-rolled steel plate was then coated with a surface density of 4.0 kg / m2. ２The vibration-damping properties were measured by evaluating the loss factor at each temperature (20°C, 35°C, 50°C) using the cantilever beam method (loss factor measurement system manufactured by Ono Sokki Co., Ltd.). The various properties of the vibration-damping coatings 1 to 12 and the comparative coatings 1 to 3 are shown in Tables 3 and 4.

[0084]

[0085]

[0086] From the results of Examples 1 to 12 described above, it was found that resin compositions for vibration dampers that contain polymer emulsion particles and have multiple peaks in the particle size distribution measured using a particle size distribution measuring device based on the dynamic light scattering method have sufficient vibration damping properties when forming a coating film, and are also very excellent in low-temperature drying properties and coating film stability.

Claims

1. The particle size distribution of the emulsion contains polymer emulsion particles, and a plurality of peaks are present in the particle size distribution measured using a particle size distribution analyzer based on a dynamic light scattering method. A resin composition for vibration damping materials having a nonvolatile content of 57% by mass or more.

2. A polymer emulsion particle containing polymer emulsion particles, wherein a particle size distribution measured using a particle size distribution analyzer based on a dynamic light scattering method has multiple peaks, the polymer emulsion particles contain a sulfosuccinic acid half ester (salt), The resin composition for vibration damping materials further comprises the polymer emulsion particles containing a polyoxyalkylene secondary alkyl ether.

3. 3. The resin composition for vibration damping materials according to claim 1, wherein the particle size has a first peak in the range of 300 nm to 800 nm and a second peak in the range of 50 nm to 150 nm.

4. 4. The resin composition for vibration damping materials according to claim 3, wherein the total volume ratio of the second peak and subsequent peaks to the entire particle size distribution is 3% by volume or more and 50% by volume or less.

5. 3. The resin composition for vibration damping materials according to claim 1, which has a viscosity at 25°C of 10 mPa·s or more and 5000 mPa·s or less.

6. 2. The resin composition for vibration damping materials according to claim 1, wherein the polymer emulsion particles contain a sulfosuccinic acid half ester (salt).

7. 3. The resin composition for vibration damping materials according to claim 1, wherein the polymer emulsion particles have a weight average molecular weight of 18,000 or more and 300,000 or less.

8. A method for producing a resin composition for vibration damping materials containing polymer emulsion particles, comprising: The production method includes a polymerization step of emulsion polymerization using a monomer emulsion containing a monomer component and an emulsifier, the polymerization step includes an initial polymerization step of emulsion polymerization using a part of the monomer emulsion, a dropping step of dropping the remaining monomer emulsion into a polymerization reaction liquid, and an aging step following the dropping step; The polymerization step is a method for producing a resin composition for vibration damping materials, which comprises adding an emulsifier to a polymerization reaction liquid containing unreacted monomer components and an emulsifier.

9. 9. The method for producing a resin composition for vibration damping materials according to claim 8, wherein the emulsifier added to the polymerization reaction liquid is an anionic emulsifier.

10. 10. The method for producing a resin composition for vibration damping materials according to claim 8 or 9, wherein a mass ratio of the emulsifier contained in the monomer emulsion to the emulsifier other than the emulsifier added to the polymerization reaction liquid is 4.0 / 1.0 to 0.5 / 1.

0.

11. The method for producing a resin composition for vibration damping materials according to claim 8 or 9, wherein the step of adding the emulsifier is carried out in a dropping step or an aging step.

12. 10. The method for producing a resin composition for vibration damping materials according to claim 8, wherein the polymerization step comprises adding a polymerization chain transfer agent to a polymerization reaction liquid containing unreacted monomer components and an emulsifier.

13. The monomer emulsion further contains a polymerization chain transfer agent, 13. The method for producing a resin composition for vibration damping materials according to claim 12, wherein a mass ratio of the polymerization chain transfer agent contained in the monomer emulsion to a polymerization chain transfer agent other than the polymerization chain transfer agent added to the polymerization reaction liquid is 20.0 / 1.0 to 1.0 / 1.

0.

14. A method for producing a resin composition for vibration damping material as described in claim 8 or 9, wherein the step of adding the emulsifier includes adding the emulsifier when the polymerization rate of the monomer emulsion is more than 45% and not more than 90%.

15. A method for producing a resin composition for vibration damping material as described in claim 8 or 9, wherein the step of adding the emulsifier includes adding the emulsifier for a dropping time of 50% or more of the total dropping time of the monomer emulsion.