JP5685001B2 - Damping emulsion and damping composition - Google Patents

Description

The present invention relates to a damping material emulsion and a damping material composition. More specifically, the present invention relates to an emulsion for damping material and a damping material composition useful as a damping material for preventing vibration and noise in various structures and maintaining silence.

The damping material is for keeping vibration and noise in various structures and keeping quiet, for example, in addition to being used under the indoor floor of an automobile, a railway vehicle, a ship, an aircraft, an electrical device, Widely used in building structures and construction equipment. As a material used for such a damping material, conventionally, a molded product such as a plate-shaped molded body or a sheet-shaped molded body made of a material having vibration absorption performance and sound absorption performance has been used. If the shape of the location where the sound is generated is complicated, it is difficult to apply these molded products to the location where the vibration is generated, so a method for improving workability and fully exhibiting the damping performance Various studies have been made. For example, an asphalt sheet containing an inorganic powder has been used under the floor of an automobile, etc., but it is necessary to heat-seal, so improvement in workability and the like is desired, and a composition that forms a vibration damping material And polymers have been studied.

Thus, as an alternative material for such molded products, coating-type damping materials (paints) have been developed. For example, a coating film formed by spraying or applying an arbitrary method to a corresponding portion. Thus, various vibration-damping paints that can obtain a vibration absorption effect and a sound absorption effect have been proposed. Specifically, for example, as a water-based vibration-damping paint with improved coating film hardness obtained by blending a synthetic resin powder with a color developing agent such as asphalt, rubber, synthetic resin, and the like suitable for indoor use in automobiles, Anti-vibration coatings in which activated carbon is dispersed as a filler in a resin emulsion have been developed. However, even with these conventional products, the vibration damping performance is still not at a sufficiently satisfactory level, and there is a need for a technique that can further exhibit the vibration damping performance.

As a material used for the coating type damping material, for example, an emulsion for an aqueous damping material containing at least a polymer having a low glass transition temperature and a polymer having a high glass transition temperature (see, for example, Patent Document 1) ), Or an emulsion for a vibration damping material containing particles having a core part made of an acrylic copolymer (A) and a shell part made of an acrylic copolymer (B), the acrylic copolymer (A ) And / or emulsions for vibration damping materials in which the weight average molecular weight of particles having a core part and a shell part is 20,000 to 250,000 (for example, see Patent Document 2). .

JP 2005-281576 A (page 1-2) International Publication No. 2007/023819 (Page 1-2)

As described above, various materials have been studied, and the emulsion for vibration damping materials described in Patent Documents 1 and 2 can exhibit excellent vibration damping properties in a wide temperature range. It has become a useful technology. However, emulsions for vibration damping materials are used in various applications as described above, and various physical properties corresponding to each application are required in addition to vibration damping properties. As a result, there was room to devise a damping material with a high degree of freedom in design that can exhibit excellent damping performance and can easily design damping materials for various applications. .

The present invention has been made in view of the above situation, and has excellent vibration damping performance in a wide temperature range, and it is easy to design a vibration damping material according to required conditions. An object of the present invention is to provide a useful emulsion for vibration damping materials.

The present inventor has studied various emulsions for vibration damping materials, paying attention to the fact that vibration damping is expressed by converting kinetic energy due to vibration into thermal energy due to friction, and efficiently converting the kinetic energy due to vibration into thermal energy. Various studies were conducted on emulsions that can be converted to The emulsion is a mixture of at least two kinds of polymers, and each polymer is composed of one kind or two or more kinds of polymerization components (polymers). When sufficient interphase friction occurs, the vibration energy is converted into thermal energy by the friction, and it is considered that excellent vibration damping is exhibited. Therefore, the emulsion for vibration damping materials is obtained by mixing two or more types of polymers, each polymer containing one or more polymerization components, and the SP value (solubility coefficient) of each polymerization component. It was found that when at least one of the differences was 0.2 or more, an emulsion for a vibration damping material exhibiting excellent vibration damping properties was obtained. This is considered to be because the compatibility between the polymerization components was lowered by giving a difference in SP value in the combination of at least one polymerization component, and interphase friction occurred, and the SP value difference was set to 0.2 or more. By doing so, it is considered that sufficient interphase friction occurs to exhibit excellent vibration damping properties.
In this emulsion for vibration damping material, since it is only necessary to have a difference in SP value in the combination of at least one polymerization component among the contained polymerization components, the degree of freedom in designing the emulsion is increased, and excellent vibration damping is achieved. In addition to the properties, it is possible to easily design the damping material according to the required conditions, so by making the emulsion for damping material like this, the above problem can be solved brilliantly The present inventors have arrived at the present invention by conceiving what can be done.

That is, the present invention is an emulsion for a vibration damping material obtained by mixing two or more kinds of polymers, wherein each of the polymers includes one or more kinds of polymerization components, The emulsion for vibration damping materials in which at least one of the differences in the SP values of the polymerization components is 0.2 or more.
The present invention is described in detail below.

Although the emulsion for vibration damping materials of the present invention is obtained by mixing two or more kinds of polymers, it may contain other components as long as it contains two or more kinds of polymers. In addition, the polymer usually exists in a form dispersed in a medium. That is, the above damping material emulsion is composed of a medium and a polymer dispersed in the medium.
The medium is preferably an aqueous medium, and examples thereof include water and a mixed solvent of water and a solvent mixed with water. Among them, in consideration of safety and environmental impact when applying the composition containing the emulsion for vibration damping material of the present invention, it is preferable that water is 50% by mass or more in 100% by mass of the aqueous medium. . More preferably, it is 70 mass% or more, More preferably, it is 100 mass%, ie, it is using water as a medium.
Each of the above polymers contains one or more polymerization components, but may contain other components as long as the polymerization components are included.
In the present invention, the polymer contained in the damping material emulsion is composed of a polymer having a single composition (polymer composed of a single polymer portion) or a plurality of polymer portions having different compositions. In the present invention, a polymer portion that contains polymers and constitutes these polymers is referred to as a polymerization component.

The emulsion for vibration damping materials is such that at least one of the differences in SP value (solubility coefficient) of each polymerization component is 0.2 or more, but at least of the polymerization components contained in the emulsion for vibration damping materials It is sufficient that the difference in SP value is 0.2 or more in one polymerization component combination. For example, in other various physical properties such as the glass transition temperature, the type of monomer used, the proportion of monomer used, etc. May be the same or different. In addition, the SP value difference between other combinations of polymerization components is not particularly limited, and in addition to the above, other SP components other than at least one combination having an SP value difference of 0.2 or more, the SP value May be the same or different.
Thus, by setting the SP value difference to 0.2 or more in the combination of at least one polymerization component, the compatibility between the polymerization components having the SP value difference of 0.2 or more is lowered, and interphase friction occurs. For this reason, it is considered that the kinetic energy due to vibration is converted into thermal energy by this frictional force, and the damping property is exhibited. The SP value difference is preferably 0.25 or more, and more preferably 0.3 or more. Moreover, when SP value difference becomes large too much, the compatibility between the polymerization components with a large SP value difference will become low too much. For this reason, there is a tendency of separation between phases, and the interaction between phases decreases, so that there is a possibility that the frictional force is reduced and sufficient vibration damping properties are not exhibited. The upper limit of the SP value difference is preferably 2.0 or less, and more preferably 1.5 or less.

The SP value of the polymerization component can be determined by, for example, the following Small formula.

In the formula, δ is the SP value of the polymerization component. Δe ₁ is a calculated value (kcal / mol) of evaporation energy of each monomer component constituting the polymerization component, and ΣΔe ₁ is a total value of the calculated values of all monomer components constituting the polymerization component. is there. ΔV _m is a calculated value (ml / mol) of each monomer component constituting the polymerization component, and ΣΔV _m is a sum of the calculated values of all monomer components constituting the polymerization component. . x is a molar distribution of each component of the monomer constituting the polymerization component.
Note that normally used calculation values can be used for the evaporation energy of the monomer component and the molecular volume of the monomer component.
Thus, the SP value of the polymerization component can be adjusted by adjusting the type of monomer and the composition ratio thereof, thereby enabling the SP value difference between the polymerization components to be adjusted. Become.

The blending ratio of each polymer included in the emulsion for vibration damping material of the present invention is not particularly limited. For example, when two kinds of polymers are included, the blending ratio of each polymer is 1/9 to 9/1. preferable. More preferably, it is 2/8 to 8/2, and still more preferably 3/7 to 7/3.

The presence form of each of at least two kinds of polymers contained in the emulsion for vibration damping material of the present invention is not particularly limited, and is a form that is a polymer containing one kind of polymerization component, and a polymerization ingredient that contains two or more kinds of polymerization components. The form that is a mixture of the above, a form having a core-shell structure containing two or more polymerization components, and having a core part and a shell part, etc., among these, as the emulsion for vibration damping material of the present invention, It is preferable to contain at least one polymer having a core / shell structure. That is, the emulsion for vibration damping materials of the present invention is a form containing at least one polymer having a core / shell structure containing two or more polymerization components and another polymer, or a core / shell containing two or more polymerization components. A form containing at least two kinds of polymers having a shell structure is preferable. By setting it as such a form, it will be excellent in the damping property in the wide range within a practical temperature range. Especially in the high temperature range, it exhibits excellent vibration damping performance compared to other forms of vibration damping composition. As a result, within the practical temperature range, the vibration damping performance covers a wide range from normal temperature to high temperature range. Can be demonstrated.
Here, the other polymer means a polymer having no core / shell structure.

When the emulsion for vibration damping materials of the present invention is in a form containing at least one polymer having a core / shell structure, the content of the polymer having the core / shell structure is the solid content of the emulsion for vibration damping materials. The solid content is preferably 40 to 100 parts by weight with respect to 100 parts by weight. By setting it as such a range, the effect obtained by making the emulsion for vibration damping materials contain the polymer of the at least 1 sort (s) or more core-shell structure mentioned above can fully be exhibited. More preferably, it is 50-100 weight part, More preferably, it is 60-100 weight part.

In the case of a form containing at least one polymer having a core / shell structure containing two or more kinds of the above-mentioned polymerization components and another polymer, a form in which at least one of the SP values of the respective polymerization components is 0.2 or more For example, the difference in SP value between the polymerization component forming the core of the core-shell structure polymer and the polymerization component forming the shell, the polymerization component forming the core of the core-shell structure, and other components SP value difference with at least one polymerization component contained in the polymer, SP value difference between the polymerization component forming the shell part of the core / shell structure polymer and at least one polymerization component contained in the other polymer, and In the case where two or more kinds of polymerization components are contained in the other polymer, the SP value difference between any two of the polymerization components may be 0.2 or more. Be As described above, the emulsion for vibration damping materials of the present invention contains at least one polymer having a core / shell structure containing two or more kinds of polymerization components and another polymer, and each of the polymers having the core / shell structure. It is also a preferred embodiment of the present invention that at least one of the differences between the SP value of the polymerization component and the SP value of the polymerization component of another polymer is 0.2 or more.
In particular, in the case of a polymer having a core / shell structure containing three or more kinds of polymerization components, in addition to the above-described SP value difference between the polymerization components, another polymerization component that forms the core portion and another component that forms the core portion. Any of the polymerization components contained in one core / shell structure polymer such as a difference in SP value from the polymerization component, or a difference in SP value between the polymerization component forming the shell portion and another polymerization component forming the shell portion The SP value difference in the combination of two kinds of polymerization components may be 0.2 or more.

In the case of a form containing at least two kinds of core-shell structure polymers containing two or more kinds of the above-mentioned polymerization components, examples of the form in which at least one of the SP values of the respective polymerization components is 0.2 or more include: SP value difference between polymerization component forming one polymer core and polymerization component forming shell, polymerization component forming one polymer core, and another polymer core SP value difference with a polymerization component forming a polymer, SP value difference between a polymerization component forming a core part of one kind of polymer and a polymerization component forming a shell part of another kind of polymer, The SP value difference of the polymerization component which forms the shell part of another polymer and the polymerization component which forms the shell part of another one type of polymer has an SP value difference of 0.2 or more. As described above, the emulsion for a vibration damping material of the present invention contains at least two kinds of polymers having a core / shell structure including two or more kinds of polymerization components, and the SP value of each polymerization component of the polymer having the core / shell structure is determined. It is also one of the preferred embodiments of the present invention that at least one of the differences is 0.2 or more.
In particular, in the case of a polymer having a core / shell structure in which three or more kinds of polymerization components are contained, in addition to the SP value difference between the polymerization components described above, the polymerization component that forms the core portion and the other that forms the core portion. Any of the polymerization components contained in one type of core-shell structure polymer such as the difference in SP value from the other polymerization component and the difference in SP value between the polymerization component forming the shell portion and another polymerization component forming the shell portion Any SP value difference in the combination of the two polymerization components may be 0.2 or more.

In the damping material emulsion of the present invention, at least one of the differences in the SP values of the polymerization components may be 0.2 or more. Among the polymerization components contained in the damping material emulsion, Even in the combination, if the SP value difference is 0.2 or more, it is possible to obtain an emulsion for a vibration damping material having further excellent vibration damping properties.
That is, it is one of the preferred embodiments of the present invention that the emulsion for vibration damping materials has a difference in SP value of each polymerization component of 0.2 or more.

In the core-shell structure polymer, the polymer forming the core part and the polymer forming the shell part are, for example, a weight average molecular weight, a glass transition temperature, an SP value (solubility coefficient), and a single amount used. What is necessary is just to be different in any of various physical properties, such as the kind of body and the usage rate of a monomer. Among them, it is preferable that there is a difference in at least one of the weight average molecular weight and the glass transition temperature.
For example, the difference in glass transition temperature (Tg) between the monomer component forming the core part and the monomer component forming the shell part is preferably 10 to 60 ° C. When the difference in Tg is less than 10 ° C. or greater than 60 ° C., there is a possibility that vibration damping properties cannot be obtained over a wide temperature range (20 ° C. to 60 ° C.). More preferably, the difference in Tg is 15 to 55 ° C, and further preferably 20 to 50 ° C.
The emulsion of the polymer having the core / shell structure can be obtained by using an emulsion polymerization method (multistage polymerization) described later.

Examples of the form having the core part and the shell part include a core-shell composite structure and a microdomain structure in which the core part and the shell part are not completely compatible but formed inhomogeneously. Among these, a core / shell composite structure is preferable in order to sufficiently draw out the characteristics of the emulsion and produce a stable emulsion.
In the core-shell composite structure, it is preferable that the surface of the core portion is covered with the shell portion. In this case, it is preferable that the surface of the core part is completely covered with the shell part, but it may not be completely covered. For example, the core part may be covered in a mesh shape or in some places. The part may be exposed.

It is preferable that the vibration damping material emulsion has a glass transition temperature (Tg) of -20 to 30 ° C. Thereby, it becomes possible to exhibit higher vibration damping properties under a wide temperature range. More preferably, it is -20-25 degreeC, More preferably, it is -15-20 degreeC. The Tg (total Tg) calculated from the monomer composition used in all polymerization steps is preferably in the above range.
The Tg can be calculated from the following Fox equation (unit: K) using the glass transition temperature (Tgn) of the homopolymer (homopolymer) of each monomer constituting the emulsion.

In the formula, Tg is the glass transition temperature of the polymerization component. Wn represents the mass fraction (mass%) of the monomer n with respect to all the monomer components. Tgn represents the glass transition temperature (unit: K, absolute temperature) of the homopolymer composed of monomer n.

Here, it is preferable that the two or more polymers contained in the emulsion for vibration damping materials have different Tg. That is, it is preferable that the emulsion for vibration damping materials is composed of two or more kinds of polymers having different Tg. By providing a difference in Tg, it becomes possible to develop a higher vibration damping property under a wide temperature range, and the vibration damping property in a practical range of 20 to 60 ° C. is remarkably improved. Become.
In addition, when three or more types of polymers are included, it is sufficient that at least two of these polymers have different Tg, and the remaining one or more types have the same Tg as one of the two types of polymers. Also good.

The polymer Tg is preferably −10 to 30 ° C. in the polymer having the highest Tg. Thereby, the drying property of the damping material coating film formed using the coating material containing the emulsion for damping material of the present invention becomes good, and the expansion and cracks of the coating film surface are sufficiently suppressed. . That is, a vibration damping material having extremely excellent vibration damping properties is formed. More preferably, it is -5-30 degreeC, More preferably, it is 0-30 degreeC. Moreover, in the polymer with the lowest Tg, it is suitable that it is -50-10 degreeC, and it becomes possible to give the damping material which has the more excellent damping property by this. More preferably, it is −30 to 10 ° C.
The Tg difference between the polymer having the highest Tg and the polymer having the lowest Tg is preferably 10 to 60 ° C. If the difference is less than 10 ° C. or the temperature difference is too large, there is a possibility that the vibration damping performance in the practical range may not be sufficient. More preferably, it is 15-55 degreeC, More preferably, it is 20-50 degreeC.

Furthermore, in 1 type or 2 or more types of polymerization components contained in the said polymer, although Tg may differ, it may be the same, but it is suitable that Tg differs. Furthermore, in the polymerization component having the highest Tg, the temperature is preferably 0 to 30 ° C. More preferably, it is 5-30 degreeC. Moreover, in the polymerization component having the lowest Tg, it is preferable that the temperature is -20 to 0 ° C. This makes it possible to provide a vibration damping material having excellent vibration damping properties. More preferably, it is -20--5 degreeC.
The Tg difference between the polymerization component having the highest Tg and the polymerization component having the lowest Tg is preferably 10 to 60 ° C. If the difference is less than 10 ° C. or the temperature difference is too large, there is a possibility that the vibration damping performance in the practical range may not be sufficient. More preferably, it is 15-55 degreeC, More preferably, it is 20-50 degreeC.
As described above, the emulsion for a vibration damping material of the present invention contains at least two or more kinds of polymerization components, and the polymerization components are combined with those having different Tg, and the polymerization component having the above Tg. By using, it becomes possible to effectively exhibit vibration damping properties in a practical temperature range.

The emulsion for vibration damping materials preferably has a weight average molecular weight of 20,000 to 400,000. When the molecular weight is less than 20,000 or more than 400,000, the coating film surface state at the time of heat drying becomes poor, and as a result, good vibration damping properties are not exhibited. More preferably, it is 30000-350,000, More preferably, it is 40000-300000.
The weight average molecular weight can be determined, for example, by GPC (gel permeation chromatography) measurement under the following measurement conditions.
Measuring instrument: HLC-8120GPC (trade name, manufactured by Tosoh Corporation)
Molecular weight column: TSK-GEL GMHXL-L and TSK-GELG5000HXL (both manufactured by Tosoh Corporation) are connected in series. Eluent: Tetrahydrofuran (THF)
Standard material for calibration curve: Polystyrene (manufactured by Tosoh Corporation)
Measurement method: The measurement object is dissolved in THF so that the solid content is about 0.2% by mass, and the molecular weight is measured using an object obtained by filtration through a filter as a measurement sample.

It is also preferable that the emulsion for vibration damping materials has an average particle diameter of emulsion particles of 100 to 400 nm. By using emulsion particles having an average particle diameter in this range as a damping material, the basic performance required for the damping material can be made sufficient, and the damping performance can be further improved. .
The average particle size (volume average particle size) can be determined by, for example, diluting the emulsion with distilled water and thoroughly stirring and mixing, then collecting about 10 ml in a glass cell, and measuring the particle size distribution analyzer (Particle) by the dynamic light scattering method. It can be determined by measuring with “NICOMP Model 380” manufactured by Sizing Systems.

The emulsion particles having the above average particle diameter preferably have a particle size distribution defined by a value obtained by dividing the standard deviation by the volume average particle diameter (standard deviation / volume average particle diameter × 100) of 40% or less. When the particle size distribution exceeds 40%, the width of the particle size distribution of the emulsion particles becomes very wide, and some of the particles contain coarse particles. Therefore, the emulsion for damping material is affected by such coarse particles. However, there is a possibility that sufficient heat drying property cannot be exhibited. More preferably, it is 30% or less.

A particularly preferred form of the emulsion for a vibration damping material is a form having a glass transition point of -20 to 30 ° C. and a weight average molecular weight of 20,000 to 400,000. Since the vibration performance is more fully exhibited, it is particularly suitable for use as a damping material. Most preferably, the glass transition point is -20 to 30 ° C, the weight average molecular weight is 20,000 to 400,000, and the average particle diameter of the emulsion particles is 100 to 400 nm.

Further, as the polymerization component, at least one of the polymerization components has a glass transition temperature of −20 to 0 ° C. and a weight average molecular weight of 20000 to 400,000, and at least one of the other polymerization components has a glass transition temperature. It is one of the preferred embodiments of the present invention that the weight average molecular weight is 0 to 30 ° C. and the weight average molecular weight is 20,000 to 400,000.

Although it does not specifically limit as a viscosity of the said emulsion for damping materials, For example, it is preferable that it is 1-10000 mPa * s, More preferably, it is 5-3000 mPa * s, More preferably, it is 10-1000 mPa * s. It is.
The viscosity can be measured using a B-type rotational viscometer under the conditions of 25 ° C. and 20 rpm.

The monomer component that is a raw material for the polymerization component is not particularly limited as long as it can exert the effects of the present invention, but it preferably includes an unsaturated carboxylic acid monomer. More preferably, it comprises an unsaturated carboxylic acid monomer and other copolymerizable unsaturated monomers. By containing an unsaturated carboxylic acid monomer, the dispersibility of the filler such as inorganic powder is improved in the vibration damping composition including the emulsion for the vibration damping material, and vibration damping is further improved. By including a copolymerizable unsaturated monomer, it becomes easy to adjust the acid value, glass transition point (Tg), physical properties and the like of the emulsion for vibration damping materials. In addition, due to the synergistic effect of the structural units formed from these monomers, excellent heat drying properties and vibration damping properties can be more fully exhibited in the water-based vibration damping material. Especially, 0.1-20 mol% of unsaturated carboxylic acid monomers and 80-99.9 mol% of other copolymerizable unsaturated monomers are contained with respect to the total amount of monomer components of 100 mol%. Is preferred. If the unsaturated carboxylic acid monomer is less than 0.1 mol% or more than 20 mol%, in any case, the emulsion for vibration damping materials may not be produced more stably. More preferably, the unsaturated carboxylic acid monomer is contained in an amount of 0.5 to 10 mol%, and other copolymerizable unsaturated monomer is contained in an amount of 90 to 99 mol%.
In the case where the polymer is a polymer emulsion particle having a core portion and a shell portion, the unsaturated carboxylic acid monomer and other copolymerizable unsaturated monomer form the core portion of the emulsion. It may be contained in any of the monomer component and the monomer component forming the shell portion, and may be used for both of them.

The unsaturated carboxylic acid monomer is not particularly limited as long as it is a compound having an unsaturated bond and a carboxyl group in the molecule. However, in order to further improve vibration damping properties, an ethylenically unsaturated carboxylic acid monomer is not limited. It is preferred to include a monomer. As the ethylenically unsaturated carboxylic acid monomer, for example, (meth) acrylic acid, crotonic acid, citraconic acid, itaconic acid, fumaric acid, maleic acid, maleic anhydride and the like, and salts thereof are suitable. These 1 type (s) or 2 or more types can be used. Among them, (meth) acrylic acid or a salt thereof (hereinafter also referred to as “(meth) acrylic acid monomer”) is preferable.
As the salt, metal salts, ammonium salts, organic amine salts and the like are suitable. Examples of the metal atom forming the metal salt include monovalent metal atoms such as alkali metal atoms such as lithium, sodium and potassium; divalent metal atoms such as alkaline earth metal atoms such as calcium and magnesium; aluminum, Trivalent metal atoms such as iron are suitable, and the organic amine salt is preferably an alkanolamine salt such as an ethanolamine salt, diethanolamine salt, or triethanolamine salt, or a triethylamine salt.

The other copolymerizable unsaturated monomer is not particularly limited as long as it is copolymerizable with the unsaturated carboxylic acid monomer. For example, other than the (meth) acrylic monomer Unsaturated monomers having a (meth) acryloyl group (hereinafter also referred to as “(meth) acrylic monomers”), unsaturated monomers having an aromatic ring, unsaturated monomers having a nitrogen atom Preferred examples include a polymerizable monomer having a glass transition temperature of 0 ° C. or less, an unsaturated monomer having a functional group, and the like, and using one or more of them. it can. Among these, it is preferable to use a (meth) acrylic monomer or an unsaturated monomer having an aromatic ring.

Examples of the (meth) acrylic monomer include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, pentyl acrylate, pentyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, octyl acrylate, octyl methacrylate, isooctyl acrylate, isooctyl Methacrylate, nonyl acrylate, nonyl methacrylate, isononyl acrylate, isononyl methacrylate, decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, vinyl formate, vinyl acetate, vinyl propionate, 2-hydroxyethyl acrylate, 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 diacrylate In addition to methacrylate, allyl acrylate, allyl methacrylate, and the like, salts and esterified products thereof can be used.
In addition, as said salt, it is preferable that it is a form similar to the salt of the (meth) acrylic-acid type monomer mentioned above.

As described above, the monomer component may include an unsaturated monomer having a (meth) acryloyl group such as a (meth) acrylic acid monomer or a (meth) acrylic monomer. Is preferred. That is, at least one of the monomer components is C (R ¹ ₂ ) = CH—COOR ² or C (R ³ ₂ ) = C (CH ₃ ) —COOR ⁴ (R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group. Especially, it is preferable to make a (meth) acrylic acid-type monomer essential, and it is more preferable that both a (meth) acrylic-acid type monomer and a (meth) acrylic-type monomer are included. Thus, the form in which the monomer component contains (meth) acrylic acid as an unsaturated carboxylic acid monomer and an acrylic monomer as another copolymerizable unsaturated monomer is This is one of the preferred forms of the invention.
In addition, as content of the unsaturated monomer which has the (meth) acryloyl group in the said monomer component, ie, the above-mentioned (meth) acrylic-acid type monomer and (meth) acrylic-type monomer, Is preferably 20% by mass or more in 100% by mass of all monomer components. As a result, vibration damping is further improved. More preferably, it is 30 mass% or more.

Examples of the unsaturated monomer having an aromatic ring include divinylbenzene, styrene, α-methylstyrene, vinyltoluene, and ethylvinylbenzene. Among these, styrene is preferable.
Usually, emulsions for vibration damping materials prepared from monomer components containing unsaturated monomers having such aromatic rings are different in copolymerizability with other monomers such as acrylic monomers. Therefore, it is often difficult to achieve excellent vibration damping properties. However, as in the present invention, among the polymerization components contained in the damping material emulsion, the unsaturated unit amount having an aromatic ring is obtained by setting the difference in SP value to 0.2 or more in the combination of at least one polymerization component. Even an emulsion for a vibration damping material prepared from a monomer component containing a large amount of body can exhibit excellent vibration damping properties. Therefore, when the monomer component contains a large amount of unsaturated monomers having an aromatic ring, it can be said that the present invention can exert its effects more remarkably.
It is preferable that content of the unsaturated monomer which has an aromatic ring is 10-80 mass% with respect to 100 mass% of all the monomer components. More preferably, it is 15-75 mass%, More preferably, it is 20-70 mass%. Most preferably, it is 30-70 mass%.

Examples of the unsaturated monomer having a nitrogen atom include acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, diacetone acrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, Ni-butoxymethyl (meth) acrylamide, etc. are mentioned.
As a ratio of the unsaturated monomer which has the said nitrogen atom, it is suitable that it is 0-40 mass% in 100 mass% of all the monomer components.

By including a polymerizable monomer having a glass transition temperature of 0 ° C. or lower in the homopolymer (homopolymer), vibration damping properties in a wide temperature range are further improved. Although it is suitable to use 1 or more types of such polymerizable monomers, it is more preferable to use 2 or more types. Moreover, when obtaining the said polymer emulsion by multistage polymerization, it is suitable that the monomer component used in each process contains 1 or more types of the said polymerizable monomer, respectively.
In addition, in this specification, the glass transition temperature of a homopolymer means the glass transition temperature (Tg) of the hardened | cured material of a homopolymer, for example, according to JIS K-7121-1987 "Plastic transition temperature measuring method". Can be measured, and “POLYMER HANDBOOK” can be referred to.

In the unsaturated monomer having the functional group, the functional group may be any functional group that can be cross-linked when the damping material emulsion is obtained by polymerization. By such an action of the functional group, the film forming property and heat drying property of the emulsion for vibration damping materials are further improved. Specific examples include an epoxy group, an oxazoline group, a carbodiimide group, an aziridinyl group, an isocyanate group, a methylol group, a vinyl ether group, a cyclocarbonate group, an alkoxysilane group, and the like. You may have.

Examples of the unsaturated monomer having a functional group include divinylbenzene, ethylene glycol di (meth) acrylate, N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, and Nn-butoxymethyl. (Meth) acrylamide, Ni-butoxymethyl (meth) acrylamide, N-methylol (meth) acrylamide, diallyl phthalate, diallyl terephthalate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di ( (Meth) acrylate, tetramethylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl Polyfunctional unsaturated monomers such as Koruji (meth) acrylate; glycidyl (meth) acrylate, glycidyl group-containing unsaturated monomers such as acrylic glycidyl ether. Among these, it is preferable to use an unsaturated monomer (polyfunctional unsaturated monomer) having two or more functional groups.
The content of the unsaturated monomer having a functional group is preferably less than 10% by mass, more preferably 0.1 to 3% by mass with respect to 100% by mass of all monomer components. .

The polymerization component may have a carboxyl group neutralized with a polyvalent metal base (hereinafter also referred to as “neutralized carboxyl group”). Such a polymerization component can be obtained by polymerizing the monomer component and then adding a polyvalent metal base.
The polyvalent metal base is a compound represented by M (OH) _n (wherein M represents a metal element having a valence of 2 or more. N represents an integer of 2 or more). In the formula, n is a numerical value determined by the valence of M, and M is, for example, an alkaline earth metal such as Be, Mg, Ca, Sr, Ba, and Ra; Cr, Mn, Fe, Cu, and the like Transition metals; base metals such as Al, etc. Among these, an alkaline earth metal is preferable. In addition, the polyvalent metal base can use 1 type (s) or 2 or more types.

Moreover, it is suitable that the pH of the emulsion for vibration damping materials of the present invention having a neutralized carboxyl group is 2 to 10 at 25 ° C., for example. More preferably, it is 3-9, More preferably, it is 7-8. The pH of the emulsion can be adjusted by adding a commonly used neutralizing agent such as aqueous ammonia, water-soluble amines, aqueous alkali hydroxide, etc., if necessary, in addition to the polyvalent metal base described above.
The pH can be measured using a pH meter (for example, “F-23” manufactured by Horiba, Ltd.).

As a method for producing the emulsion for vibration damping material of the present invention, the monomer component is polymerized by emulsion polymerization in the presence of an emulsifier, but the form for carrying out emulsion polymerization is not particularly limited. And / or in the presence of a protective colloid, polymerization can be carried out by appropriately adding a monomer component and a polymerization initiator in an aqueous medium. Moreover, it is preferable to use a polymerization chain transfer agent or the like for molecular weight adjustment.
When the polymer contained in the emulsion for vibration damping material is a polymer emulsion particle having a core part and a shell part, the monomer component is emulsified in an aqueous medium in the presence of an emulsifier and / or a protective colloid. It is preferably obtained by multi-stage polymerization in which a core part is formed by polymerization, and then a monomer component is further emulsion-polymerized in an emulsion containing the core part to form a shell part.

Examples of the emulsifier include an anionic emulsifier, a cationic emulsifier, a nonionic emulsifier, an amphoteric emulsifier, and a polymer emulsifier, and one or more of these can be used.
The anionic emulsifier is not particularly limited. For example, polyoxyalkylene alkyl ether sulfate, polyoxyalkylene oleyl ether sodium sulfate, polyoxyalkylene alkylphenyl ether sulfate, alkyl diphenyl ether disulfonate, polyoxyalkylene (Mono, di, tri) styryl phenyl ether sulfate, polyoxyalkylene (mono, di, tri) benzyl phenyl ether sulfate, alkenyl succinate; sodium dodecyl sulfate, potassium dodecyl sulfate, ammonium alkyl sulfate, etc. Alkyl sulfate salt; sodium dodecyl polyglycol ether sulfate; sodium sulforicinoate; sulfonated paraffin Alkyl sulfonates such as sodium dodecyl benzene sulfonate, alkyl sulfonates such as alkali metal hydroxyethylene alkali metal sulfates; high alkyl naphthalene sulfonates; naphthalene sulfonic acid formalin condensates; sodium laurate, triethanolamine oleate, triethanolamine Fatty acid salts such as abietate; polyoxyalkyl ether sulfate ester; polyoxyethylene carboxylate sulfate ester salt; polyoxyethylene phenyl ether sulfate ester salt; succinic acid dialkyl ester sulfonate salt; polyoxyethylene alkylaryl sulfate salt Is mentioned.

Preferable specific examples of the anionic emulsifier include, for example, Latem WX, Latem 118B, Perex SS-H, Emulgen 1118S, Emulgen A-60, B-66, Lebenol WZ (manufactured by Kao Corporation), New Coal 707SF, New Coal 707SN, New Coal 714SF (manufactured by Nippon Emulsifier Co., Ltd.), New Coal 714SN, ABEX-26S, ABEX-2010, 2020, 2030, DSB (manufactured by Rhodia Nikka Co., Ltd.) and the like. In addition, emulsifiers corresponding to these nonionic types can also be used.

As the anionic emulsifier, as the reactive emulsifier, Latemul S-120, S-120A, S-180 and S-180A (all are trade names, manufactured by Kao Corporation), Eleminol JS-2 (trade names, Sanyo Kasei) ), Adekaria Soap SR-10, SR-20, SR-30 (ADEKA) and other sulfosuccinate type reactive anionic surfactants; Latemul ASK (trade name, manufactured by Kao Corporation) and other alkenyls 1 type (s) or 2 or more types, such as a succinate-type reactive anionic surfactant, can be used. Further, (meth) acrylic acid polyoxyethylene sulfonate salt (for example, “Eleminol RS-30” manufactured by Sanyo Chemical Industries, “Antox MS-60” manufactured by Nippon Emulsifier Co., Ltd.), allyloxymethylalkyloxypolyoxy Sulfate ester (salt) having an allyl group such as sulfonate salt of ethylene (for example, “Aqualon KH-10” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), ammonium polyoxyalkylene alkenyl ether sulfate (for example, “Latemul PD-” manufactured by Kao Corporation 104 "etc.) can also be used.

As the anionic emulsifier, a sulfoalkyl (carbon number 1 to 4) ester salt surfactant of an aliphatic unsaturated carboxylic acid having 3 to 5 carbon atoms can be used as a reactive emulsifier. Specific examples of such surfactants include (meth) acrylic acid sulfoalkyl ester salt type surfactants such as 2-sulfoethyl (meth) acrylate sodium salt and 3-sulfopropyl (meth) acrylate ammonium salt; Aliphatic unsaturated dicarboxylic acid alkylsulfoalkyl diester salt surfactants such as sulfopropylmaleic acid alkylester sodium salt, sulfopropylmaleic acid polyoxyethylene alkylester ammonium salt, sulfoethylfumaric acid polyoxyethylene alkylester ammonium salt, etc. Is mentioned.

The nonionic emulsifier is not particularly limited. For example, polyoxyethylene alkyl ether; polyoxyethylene alkyl aryl ether; sorbitan aliphatic ester; polyoxyethylene sorbitan aliphatic ester; aliphatic monoglyceride such as monolaurate of glycerol; Polyoxyethyleneoxypropylene copolymer; condensation products of ethylene oxide and aliphatic amines, amides or acids. Also, allyloxymethylalkoxyethylhydroxypolyoxyethylene (for example, “ADEKA rear soap ER-20” manufactured by ADEKA), polyoxyalkylene alkenyl ether (for example, “Latemul PD-420”, “Latemul PD-” manufactured by Kao Corporation) Nonionic emulsifiers having reactivity such as “430” and the like can also be used. These can be used alone or in combination of two or more.
The cationic emulsifier is not particularly limited, and examples thereof include dialkyldimethylammonium salts, ester-type dialkylammonium salts, amide-type dialkylammonium salts, dialkylimidazolinium salts, and the like, and one or more of these are used. be able to.

The amphoteric emulsifier is not particularly limited, and examples thereof include alkyldimethylaminoacetic acid betaine, alkyldimethylamine oxide, alkylcarboxymethylhydroxyethyl imidazolinium betaine, alkylamidopropyl betaine, alkylhydroxysulfobetaine, and the like. Species or two or more can be used.
The polymer emulsifier is not particularly limited. For example, polyvinyl alcohol and modified products thereof; (meth) acrylic water-soluble polymer; hydroxyethyl (meth) acrylic water-soluble polymer; hydroxypropyl (meth) acrylic water solution Polymer; polyvinylpyrrolidone and the like can be mentioned, and one or more of these can be used.

Among the above-mentioned emulsifiers, it is preferable to use a non-nonylphenyl type emulsifier from the environmental viewpoint.
The amount of the emulsifier used may be appropriately set according to the type of emulsifier to be used, the type of monomer component, and the like. The amount is preferably 10 parts by weight, and more preferably 0.5 to 5 parts by weight. More preferably, it is 1 to 3 parts by weight.

Examples of the protective colloid include polyvinyl alcohols such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, and modified polyvinyl alcohol; cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose salt; natural polysaccharides such as guar gum Etc., and one or more of these can be used. The protective colloid may be used alone or in combination with a surfactant.
The use amount of the protective colloid may be appropriately set according to the use conditions and the like. For example, it is preferably 5 parts by weight or less, more preferably 100 parts by weight based on the total amount of the monomer components. Is 3 parts by weight or less.

The aqueous medium is not particularly limited. For example, water, one or two or more mixed solvents that can be mixed with water, and a mixed solvent in which water is a main component in such a solvent. Etc. Among these, it is preferable to use water. In addition, the usage-amount of an aqueous medium should just be set suitably in consideration of the desired resin solid content of the emulsion to be obtained.

The polymerization initiator is not particularly limited as long as it is a substance that decomposes by heat and generates radical molecules, but a water-soluble initiator is preferably used. For example, persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate; water-soluble such as 2,2'-azobis (2-amidinopropane) dihydrochloride, 4,4'-azobis (4-cyanopentanoic acid) Thermal decomposition initiators such as hydrogen peroxide; hydrogen peroxide and ascorbic acid, t-butyl hydroperoxide and Rongalite, potassium persulfate and metal salts, redox polymerization of ammonium persulfate and sodium bisulfite, etc. An agent etc. are mentioned, These 1 type (s) or 2 or more types can be used.
The amount of the polymerization initiator used is not particularly limited, and may be appropriately set according to the type of the polymerization initiator. For example, the amount of the polymerization initiator is 0.1 to 100 parts by weight based on the total amount of the monomer components. The amount is preferably 2 parts by weight, and more preferably 0.2 to 1 part by weight.

In order to promote emulsion polymerization, the polymerization initiator can be used in combination with a reducing agent as necessary. Examples of the reducing agent include reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, and glucose; for example, reducing inorganic compounds such as sodium thiosulfate, sodium sulfite, sodium bisulfite, and sodium metabisulfite. These 1 type (s) or 2 or more types can be used.
It does not specifically limit as the usage-amount of the said reducing agent, For example, it is preferable that it is 0.05-1 weight part with respect to 100 weight part of total amounts of the said monomer component.

The polymerization chain transfer agent is not particularly limited. For example, alkyl mercaptans such as hexyl mercaptan, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan; carbon tetrachloride , Halogenated hydrocarbons such as carbon tetrabromide and ethylene bromide; mercaptocarboxylic acid alkyl esters such as mercaptoacetic acid 2-ethylhexyl ester, mercaptopropionic acid 2-ethylhexyl ester, mercaptopyropionic acid tridecyl ester; mercaptoacetic acid methoxybutyl Mercaptocarboxylic acid alkoxyalkyl ester such as ester, mercaptopropionic acid methoxybutyl ester; carboxylic acid mercaptoal such as octanoic acid 2-mercaptoethyl ester Glycol ester or, alpha-methylstyrene dimer, terpinolene, alpha-terpinene, .gamma.-terpinene, dipentene, anisole, allyl alcohol and the like. 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, and n-tetradecyl mercaptan. The amount of the polymerization chain transfer agent used is usually 2 parts by weight or less, preferably 1 part by weight or less with respect to 100 parts by weight of the total amount of the monomer components.

The emulsion polymerization may be performed in the presence of a chelating agent such as sodium ethylenediaminetetraacetate, a dispersing agent such as sodium polyacrylate, an inorganic salt, or the like, if necessary. Moreover, as addition methods, such as a monomer component and a polymerization initiator, methods, such as a batch addition method, a continuous addition method, a multistage addition method, are applicable, for example. Moreover, you may combine these addition methods suitably.

Regarding the emulsion polymerization conditions in the above production method, the polymerization temperature is not particularly limited, and is preferably 0 to 100 ° C., and more preferably 40 to 95 ° C., for example. Also, the polymerization time is not particularly limited, and for example, it is preferably 1 to 15 hours, and more preferably 5 to 10 hours.
Moreover, it does not specifically limit as addition methods, such as a monomer component and a polymerization initiator, For example, methods, such as a batch addition method, a continuous addition method, a multistage addition method, are applicable. Moreover, you may combine these addition methods suitably.

In the said manufacturing method, after manufacturing emulsion by emulsion polymerization, you may neutralize an emulsion with neutralizing agents other than a polyvalent metal base as needed. The neutralizing agent is not particularly limited, and for example, tertiary amines such as triethanolamine, dimethylethanolamine, diethylethanolamine and morpholine; ammonia water; sodium hydroxide and the like can be used. These may be used alone or in combination of two or more.
Here, in the present invention, since the carboxyl group in the emulsion is neutralized by the polyvalent metal base, the effect is the same whether neutralized only by the polyvalent metal base or further neutralized by the neutralizing agent. It is thought that. That is, if the number of carboxyl groups metal-bonded with a polyvalent metal base (number of moles) is within a certain range, the effect is considered to be exhibited.

The emulsion for damping material of the present invention can constitute a damping material blend together with other components as necessary. Such a vibration damping composition can form an aqueous vibration damping material that can exhibit excellent heat drying properties and vibration damping properties.
The vibration damping composition preferably contains at least the emulsion for vibration damping material, pigment, foaming agent and thickener of the present invention. For example, these components and other components contained as necessary may be used. It can be obtained by mixing using a butterfly mixer, planetary mixer, spiral mixer, kneader, dissolver or the like.
The vibration damping composition preferably has a solid content (nonvolatile content) of 80% by mass or more. The solid content means the solid content with respect to the total amount of the damping material composition of 100% by mass, and thus includes the above damping material emulsion, pigment, foaming agent, and thickener, A vibration damping composition (also referred to as a vibration damping composition) having a nonvolatile content of 80% by mass or more is also one aspect of the present invention. The non-volatile content is more preferably 85 to 95% by mass, and still more preferably 85 to 90% by mass.

Moreover, it is preferable that the pH of the vibration damping composition is 7 to 11 at 25 ° C. More preferably, it is 7-9. This pH can also be measured in the same manner as the pH of the emulsion for vibration damping materials described above.

In the above damping material composition, the content of the damping material emulsion of the present invention is such that the solid content of the damping material emulsion is 10 to 60% by mass with respect to the solid content of 100% by mass of the damping material composition. It is preferable to set so that. More preferably, it is 15-55 mass%.
The vibration damping composition may also contain other emulsion resins together with the vibration damping emulsion of the present invention. Other emulsion resins include urethane resins, SBR resins, epoxy resins, vinyl acetate resins, vinyl chloride resins, vinyl chloride-ethylene resins, vinylidene chloride resins, styrene-butadiene resins, acrylonitrile-butadiene resins, etc. These emulsion resins can be used, and one or more of these can be used. In this case, the mass ratio of the emulsion for damping material of the present invention to other emulsion resin (the emulsion for damping material of the present invention / other emulsion resin) is preferably 100 to 50/0 to 50. is there.

In the above damping material composition, examples of the pigment include coloring agents such as organic or inorganic coloring agents such as titanium oxide, carbon black, petal, Hansa yellow, benzine yellow, phthalocyanine blue, and quinacridone red; metal phosphates Examples thereof include rust preventive pigments such as salts, metal molybdates, and metal borates, and one or more of these can be used.
The blending amount of the pigment is preferably 50 to 700 parts by weight with respect to 100 parts by weight of the solid content of the emulsion for vibration damping materials. More preferably, it is 100-550 weight part.

As the foaming agent, for example, a low-boiling hydrocarbon encapsulated heated expansion capsule, an organic foaming agent, an inorganic foaming agent, and the like are suitable, and one or more of these can be used. Examples of the heated expansion capsule include Matsumoto Microsphere F-30, F-50 (manufactured by Matsumoto Yushi Co., Ltd.); EXPANSELL WU642, WU551, WU461, DU551, DU401 (manufactured by Nippon Expandcel). Examples of the organic foaming agent include azodicarbonamide, azobisisobutyronitrile, N, N-dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazine, p-oxybis (benzenesulfohydrazide), and the like. Examples of the foaming agent include sodium bicarbonate, ammonium carbonate, silicon hydride and the like.
The blending amount of the foaming agent is preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the solid content of the emulsion for vibration damping materials. More preferably, it is 1 to 3 parts by weight.

Examples of the thickener include polyvinyl alcohol, cellulose derivatives, polycarboxylic acid resins, and the like.
The blending amount of the thickener is preferably 0.01 to 2 parts by weight with respect to 100 parts by weight of the solid content of the emulsion for vibration damping materials. More preferably, it is 0.05-1.5 weight part, More preferably, it is 0.1-1 weight part.

The above vibration damping composition also includes a solvent; an aqueous cross-linking agent; a plasticizer; a stabilizer; a wetting agent; an antiseptic; an antifoaming agent; a filler; a dispersing agent; an antifoaming agent; Absorbent: In addition to additives such as antistatic agents, polyvalent metal compounds may be included. Each of these components can be used alone or in combination of two or more.

Examples of the solvent include ethylene glycol, butyl cellosolve, butyl carbitol, butyl carbitol acetate, and the like. What is necessary is just to set suitably as a compounding quantity of a solvent so that the solid content density | concentration of the emulsion for damping materials in a damping material formulation may become the range mentioned above.

Examples of the aqueous crosslinking agent include oxazoline compounds such as Epocross WS-500, WS-700, K-2010, 2020, 2030 (all trade names, manufactured by Nippon Shokubai Co., Ltd.); Adeka Resin EMN-26-60, EM- Epoxy compounds such as 101-50 (Brand name, manufactured by ADEKA); Melamine compounds such as Cymel C-325 (Brand name, manufactured by Mitsui Cytec); Block isocyanate compounds; AZO-50 (Brand name, 50% by mass) Zinc oxide compounds such as zinc oxide aqueous dispersion (manufactured by Nippon Shokubai Co., Ltd.) are preferred. The blending amount of the water-based crosslinking agent is preferably 0.01 to 20 parts by weight in solid content with respect to 100 parts by weight of solid content in the emulsion for vibration damping material, for example. More preferably 0.15 to 15 parts by weight, still more preferably 0.5 to 15 parts by weight, which may be added to the emulsion for damping material, or when other components are blended as the damping material composition You may add simultaneously.
By mixing a crosslinking agent with the emulsion for vibration damping material or the vibration damping composition, the toughness of the resin is improved, and as a result, a sufficiently high vibration damping property is exhibited in a high temperature region. Among them, it is preferable to use an oxazoline compound.

Examples of the filler include inorganic fillers such as calcium carbonate, kaolin, silica, talc, barium sulfate, alumina, iron oxide, titanium oxide, glass talk, magnesium carbonate, aluminum hydroxide, talc, diatomaceous earth, and clay; Examples of the inorganic filler include glass flakes and mica; and fibrous inorganic fillers such as metal oxide whiskers and glass fibers. The blending amount of the filler is preferably 50 to 700 parts by weight with respect to 100 parts by weight of the solid content of the emulsion for vibration damping materials. More preferably, it is 100-550 weight part.
Examples of the dispersant include inorganic dispersants such as sodium hexametaphosphate and sodium tripolyphosphate, and organic dispersants such as polycarboxylic acid-based dispersants.
Examples of the antifoaming agent include silicon-based antifoaming agents.

The vibration damping composition may further contain a polyvalent metal compound. In this case, the polyvalent metal compound improves the stability, dispersibility, heat drying property, and damping property of the damping material formed from the damping material formulation. It does not specifically limit as a polyvalent metal compound, For example, zinc oxide, zinc chloride, zinc sulfate etc. are mentioned, These 1 type (s) or 2 or more types can be used. The form of the polyvalent metal compound may be, for example, a powder, an aqueous dispersion, an emulsion dispersion, or the like. Especially, since the dispersibility in a damping material formulation improves, it is preferable to use it with the form of an aqueous dispersion or an emulsion dispersion, More preferably, it is used with the form of an emulsion dispersion. Moreover, it is preferable that the usage-amount of a polyvalent metal compound shall be 0.05-5.0 weight part with respect to 100 weight part of solid content of the said emulsion for damping materials. More preferably, it is 0.05-3.5 weight part.

The said damping material composition forms the coating film used as a damping material, for example by apply | coating to a base material and drying. The substrate is not particularly limited. Moreover, as a method of applying the vibration damping composition to the substrate, for example, it can be applied using a brush, a spatula, an air spray, an airless spray, a mortar gun, a ricin gun or the like.
The coating amount of the vibration damping composition may be appropriately set depending on the application, desired performance, etc., but it is preferable that the thickness of the coating film during drying is 2.0 to 5.0 mm. . More preferably, it is 2.5-4.5 mm. More preferably, it is 3.0-4.0 mm.
Moreover, it is also preferable to apply so that the surface density of the coating film at the time of drying (after) is 1.0 to 7.0 kg / m ² . More preferably, it is 2.0-6.0 kg / m < ² >. In addition, by using the vibration damping composition of the present invention, it is possible to obtain a coating film that hardly causes expansion and cracks during drying and that does not easily cause the paint on the inclined surface to slide off.

After applying the vibration damping composition, the condition for drying to form a coating film may be heat drying or room temperature drying, but the vibration damping composition in the present invention is heat dried. From the viewpoint of efficiency, it is preferable to heat and dry. The temperature for heat drying is preferably 100 to 150 ° C. Thus, the damping material coating film obtained by baking the damping composition at 100 to 150 ° C., wherein the coating film thickness is 2 to 5 mm, It is one of the present inventions.

The damping property of the damping material composition can be evaluated by measuring the loss factor of the film formed from the damping material composition.
The loss factor is usually expressed by η and indicates how much the vibration applied to the damping material is attenuated. The loss factor indicates that the higher the numerical value, the better the damping performance. The peak value of the loss coefficient of the film formed from the vibration damping composition is preferably 0.2 or more. More preferably, it is 0.21 or more, More preferably, it is 0.22 or more, Especially preferably, it is 0.23 or more.
As a method for measuring the loss factor, a resonance method for measuring near the resonance frequency is generally used, and there are a half width method, an attenuation rate method, and a mechanical impedance method. In the vibration damping composition of the present invention, the loss factor of the film formed from the vibration damping composition is preferably measured by a resonance method using a cantilever method (3 dB method). The measurement using the cantilever method can be performed using, for example, a loss factor measurement system manufactured by Ono Sokki Co., Ltd.
The loss factor is applied on a cold-rolled steel plate (SPCC: width 15 mm × length 250 mm × thickness 1.5 mm) with a coating volume of 3.0 mm, and baked and dried at 150 ° C. for 30 minutes. It is preferable to measure by forming a film. For example, the loss factor is preferably measured by measuring the loss factor at each temperature of 20 ° C., 30 ° C., 40 ° C., 50 ° C., and 60 ° C. by the resonance method (3 dB method) and evaluating the peak value therein. . In addition, since the practical temperature range of the film formed from the vibration damping composition is usually 20 to 60 ° C., even if the vibration damping performance is evaluated by the total loss coefficient at each temperature of 20 to 60 ° C. It is preferable that the total loss coefficient of the film formed from the vibration damping composition is a sum of the loss coefficients at 20 ° C., 40 ° C. and 60 ° C. of 0.20 or more. In the case of such a damping material composition, it can be said that sufficient damping properties are exhibited at 20 to 60 ° C., which is a practical temperature range of a film formed from the damping material composition.
The total loss coefficient is more preferably 0.27 or more, and still more preferably 0.30 or more.

The emulsion for a vibration damping material of the present invention has the above-described configuration, can exhibit basic performance required for the vibration damping material, and can form a vibration damping material that is remarkably excellent in vibration damping properties. It can be suitably applied to industrial applications such as railway vehicles, ships, aircraft, electrical equipment, building structures, construction equipment, etc.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

In the following examples, various physical properties and the like were evaluated as follows.
<Solubility coefficient (SP value)>
The SP value of each polymerization component was calculated using the following Small formula.

In the formula, δ is the SP value of the polymerization component. Δe ₁ is a calculated value (kcal / mol) of evaporation energy of each monomer component constituting the polymerization component, and ΣΔe ₁ is a total value of the calculated values of all monomer components constituting the polymerization component. is there. ΔV _m is a calculated value (ml / mol) of each monomer component constituting the polymerization component, and ΣΔV _m is a sum of the calculated values of all monomer components constituting the polymerization component. . x is a molar distribution of each component of the monomer constituting the polymerization component.

<Glass transition temperature (Tg)>
It calculated from the monomer composition used by each polymerization reaction using the following Fox formula. In addition, Tg calculated from the monomer composition used in all stages was described as “total Tg”.

In the formula, Tg is the glass transition temperature of the polymerization component. Wn represents the mass fraction (mass%) of the monomer n with respect to all the monomer components. Tgn represents the glass transition temperature (unit: K, absolute temperature) of the homopolymer composed of monomer n.

The Tg values of the respective homopolymers used for calculating the glass transition temperature (Tg) of the polymerization component according to the above Fox formula are shown below.
Methyl methacrylate (MMA): 105 ° C
Styrene (St): 100 ° C
Butyl acrylate (BA): -56 ° C
2-ethylhexyl acrylate (2EHA): -70 ° C
Methyl acrylate (MA): 9 ° C
Acrylic acid (AA): 95 ° C
Methacrylic acid (MAA): 130 ° C

<Nonvolatile content (N.V.)>
About 1 g of the obtained aqueous resin dispersion was weighed, and after 110 hours at 110 ° C. with a hot air drier, the remaining amount after drying was regarded as a non-volatile content, and the ratio to the mass before drying was expressed in mass%.
<PH>
The value at 25 ° C. was measured with a pH meter (“F-23” manufactured by Horiba, Ltd.).
<Viscosity>
Using a B-type rotational viscometer (“VISCOMETER TUB-10” manufactured by Toki Sangyo Co., Ltd.), the measurement was performed at 25 ° C. and 20 rpm.

<Average particle size>
The volume average particle diameter was measured using a particle size distribution measuring apparatus (“NICOMP Model 380” manufactured by Particle Sizing Systems) by a dynamic light scattering method.
<Weight average molecular weight>
It measured by GPC (gel permeation chromatography) on the following measurement conditions.
Measuring instrument: HLC-8120GPC (trade name, manufactured by Tosoh Corporation)
Molecular weight column: TSK-GEL GMHXL-L and TSK-GELG5000HXL (both manufactured by Tosoh Corporation) are connected in series. Eluent: Tetrahydrofuran (THF)
Standard material for calibration curve: Polystyrene (manufactured by Tosoh Corporation)
Measurement method: The molecular weight was measured using a measurement sample dissolved in THF so that the solid content was about 0.2% by mass and filtered through a filter.

(Production Example 1)
300 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. On the other hand, 165 parts of styrene, 160 parts of methyl methacrylate, 165 parts of 2-ethylhexyl acrylate, 10 parts of acrylic acid, 3 parts of t-dodecyl mercaptan, Lebenol WZ (trade name, manufactured by Kao Corporation) previously adjusted to a 20% aqueous solution. ) First stage monomer emulsion consisting of 90.0 parts and 97 parts deionized water was charged. Next, while maintaining the internal temperature of the polymerization vessel at 80 ° C., 8 parts of the above monomer emulsion, 5 parts of 5% aqueous potassium persulfate solution and 10 parts of 2% aqueous sodium hydrogensulfite solution were added, Polymerization was started. After 20 minutes, the remaining monomer emulsion was uniformly added dropwise over 120 minutes while maintaining the inside of the reaction system at 80 ° C. At the same time, 50 parts of a 5% aqueous potassium persulfate solution and 50 parts of a 2% aqueous sodium hydrogen sulfite solution were uniformly added dropwise over 120 minutes, and the temperature was maintained for 60 minutes after completion of the addition.

Next, 105 parts of styrene, 200 parts of methyl methacrylate, 200 parts of butyl acrylate, 85 parts of 2-ethylhexyl acrylate, 10 parts of acrylic acid, 3 parts of t-dodecyl mercaptan, and Lebenol WZ 90.0 previously adjusted to a 20% aqueous solution were added to the dropping funnel. The monomer emulsion of the second stage comprising 97 parts and 97 parts of deionized water was charged and dropped uniformly over 120 minutes. At the same time, 50 parts of a 5% potassium persulfate aqueous solution and 50 parts of a 2% sodium hydrogen sulfite aqueous solution were uniformly added dropwise over 120 minutes, and the same temperature was maintained for 90 minutes after the addition was completed to complete the polymerization. After cooling the obtained reaction liquid to room temperature, 10 parts of 25% aqueous ammonia was added, 55% non-volatile content, pH 8.0, viscosity 240 mPa · s, average particle diameter 250 nm, weight average molecular weight 65000, first stage SP. Emulsion A having a value of 8.59, a second stage SP value of 9.11, a first stage Tg of 10 ° C., a second stage Tg of −10 ° C., and a total Tg of 0 ° C. was obtained.

(Production Example 2)
300 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. On the other hand, 275 parts of styrene, 120 parts of 2-ethylhexyl acrylate, 5 parts of acrylic acid, 2 parts of t-dodecyl mercaptan, 90.0 parts of Lebenol WZ (trade name, manufactured by Kao Corporation) previously adjusted to a 20% aqueous solution. And a first-stage monomer emulsion consisting of 97 parts of deionized water. Next, while maintaining the internal temperature of the polymerization vessel at 80 ° C., 8 parts of the above monomer emulsion, 5 parts of 5% aqueous potassium persulfate solution and 10 parts of 2% aqueous sodium hydrogensulfite solution were added, Polymerization was started. After 20 minutes, the remaining monomer emulsion was uniformly added dropwise over 120 minutes while maintaining the inside of the reaction system at 80 ° C. At the same time, 50 parts of a 5% aqueous potassium persulfate solution and 50 parts of a 2% aqueous sodium hydrogen sulfite solution were uniformly added dropwise over 120 minutes, and the temperature was maintained for 60 minutes after completion of the addition.

Next, 240 parts of styrene, 300 parts of butyl acrylate, 40 parts of 2-ethylhexyl acrylate, 20 parts of acrylic acid, 2 parts of t-dodecyl mercaptan, 90.0 parts of rebenol WZ previously adjusted to a 20% aqueous solution and deionized water in a dropping funnel A second-stage monomer emulsion consisting of 97 parts was charged and added dropwise uniformly over 120 minutes. At the same time, 50 parts of a 5% potassium persulfate aqueous solution and 50 parts of a 2% sodium hydrogen sulfite aqueous solution were uniformly added dropwise over 120 minutes, and the same temperature was maintained for 90 minutes after the addition was completed to complete the polymerization. After cooling the obtained reaction liquid to room temperature, 12.5 parts of 25% ammonia water was added, 55% non-volatile content, pH 8.2, viscosity 210 mPa · s, average particle diameter 260 nm, weight average molecular weight 58000, first stage. The second stage SP value was 8.54, the first stage Tg was 25 ° C., the second stage Tg was −10 ° C., and the emulsion T had a total Tg of 3 ° C.

(Production Example 3)
300 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. On the other hand, 230 parts of styrene, 85 parts of butyl acrylate, 35 parts of 2-ethylhexyl acrylate, 140 parts of methyl acrylate, 10 parts of acrylic acid, 3 parts of t-dodecyl mercaptan, Levenol WZ previously adjusted to a 20% aqueous solution ( The first stage monomer emulsion consisting of 90.0 parts (trade name, manufactured by Kao Corporation) and 97 parts deionized water was charged. Next, while maintaining the internal temperature of the polymerization vessel at 80 ° C., 8 parts of the above monomer emulsion, 5 parts of 5% aqueous potassium persulfate solution and 10 parts of 2% aqueous sodium hydrogensulfite solution were added, Polymerization was started. After 20 minutes, the remaining monomer emulsion was uniformly added dropwise over 120 minutes while maintaining the inside of the reaction system at 80 ° C. At the same time, 50 parts of a 5% aqueous potassium persulfate solution and 50 parts of a 2% aqueous sodium hydrogen sulfite solution were uniformly added dropwise over 120 minutes, and the temperature was maintained for 60 minutes after completion of the addition.

Next, 140 parts of styrene, 200 parts of butyl acrylate, 40 parts of 2-ethylhexyl acrylate, 100 parts of methyl acrylate, 20 parts of acrylic acid, 3 parts of t-dodecyl mercaptan, Lebenol WZ90. A second stage monomer emulsion consisting of 0 parts and 97 parts of deionized water was charged and added dropwise uniformly over 120 minutes. At the same time, 50 parts of a 5% potassium persulfate aqueous solution and 50 parts of a 2% sodium hydrogen sulfite aqueous solution were uniformly added dropwise over 120 minutes, and the same temperature was maintained for 90 minutes after the addition was completed to complete the polymerization. After cooling the obtained reaction liquid to room temperature, 15 parts of 25% aqueous ammonia was added, 55% non-volatile content, pH 7.9, viscosity 420 mPa · s, average particle diameter 220 nm, weight average molecular weight 56000, first stage SP. An emulsion C having a value of 8.48, a second stage SP value of 8.99, a first stage Tg of 20 ° C., a second stage Tg of −10 ° C., and a total Tg of 5 ° C. was obtained.

(Production Example 4)
300 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. On the other hand, 300 parts of styrene, 160 parts of butyl acrylate, 30 parts of 2-ethylhexyl acrylate, 10 parts of acrylic acid, 3 parts of t-dodecyl mercaptan, Levenol WZ (trade name, manufactured by Kao Corporation) previously adjusted to a 20% aqueous solution. ) First stage monomer emulsion consisting of 90.0 parts and 97 parts deionized water was charged. Next, while maintaining the internal temperature of the polymerization vessel at 80 ° C., 8 parts of the above monomer emulsion, 5 parts of 5% aqueous potassium persulfate solution and 10 parts of 2% aqueous sodium hydrogensulfite solution were added, Polymerization was started. After 20 minutes, the remaining monomer emulsion was uniformly added dropwise over 120 minutes while maintaining the inside of the reaction system at 80 ° C. At the same time, 50 parts of a 5% aqueous potassium persulfate solution and 50 parts of a 2% aqueous sodium hydrogen sulfite solution were uniformly added dropwise over 120 minutes, and the temperature was maintained for 60 minutes after completion of the addition.

Next, 150 parts of styrene, 280 parts of butyl acrylate, 50 parts of methyl acrylate, 20 parts of acrylic acid, 3 parts of t-dodecyl mercaptan, 90.0 parts of Lebenol WZ previously adjusted to a 20% aqueous solution and 97 of deionized water are added to the dropping funnel. A second stage monomer emulsion consisting of parts was charged and added dropwise uniformly over 120 minutes. At the same time, 50 parts of a 5% potassium persulfate aqueous solution and 50 parts of a 2% sodium hydrogen sulfite aqueous solution were uniformly added dropwise over 120 minutes, and the same temperature was maintained for 90 minutes after the addition was completed to complete the polymerization. After cooling the obtained reaction solution to room temperature, 15 parts of 25% aqueous ammonia was added, 55% non-volatile content, pH 8.2, viscosity 510 mPa · s, average particle diameter 290 nm, weight average molecular weight 60000, first stage SP Emulsion D having a value of 8.04, a second stage SP value of 8.91, a first stage Tg of 18 ° C., a second stage of Tg−13 ° C., and a total Tg of 2 ° C. was obtained.

(Production Example 5)
300 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. On the other hand, 560 parts of styrene, 435 parts of 2-ethylhexyl acrylate, 5 parts of acrylic acid, 3 parts of t-dodecyl mercaptan, Lebenol WZ (trade name, manufactured by Kao Corp.) previously adjusted to a 20% aqueous solution in the dropping funnel. A monomer emulsion consisting of 0 parts and 194 parts deionized water was charged. Next, while maintaining the internal temperature of the polymerization vessel at 80 ° C., 4 parts of the monomer emulsion, 5 parts of 5% potassium persulfate aqueous solution, and 10 parts of 2% aqueous sodium hydrogensulfite solution were added. The initial polymerization was started. After 20 minutes, the remaining monomer emulsion was uniformly flowed down over 180 minutes while maintaining the inside of the reaction system at 80 ° C. At the same time, 100 parts of a 5% aqueous potassium persulfate solution and 100 parts of a 2% aqueous sodium hydrogen sulfite solution were allowed to flow uniformly over 180 minutes, and the same temperature was maintained for 60 minutes after completion of the dropwise addition. After cooling the resulting reaction liquid to room temperature, 3 parts of 25% aqueous ammonia was added, 55% non-volatile content, pH 8.0, viscosity 180 mPa · s, average particle diameter 270 nm, weight average molecular weight 50000, SP value 7.95. Emulsion E having a Tg of 0 ° C. was obtained.

(Production Example 6)
300 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. On the other hand, 500 parts of styrene, 210 parts of butyl acrylate, 250 parts of 2-ethylhexyl acrylate, 40 parts of methacrylic acid, 3 parts of t-dodecyl mercaptan, Lebenol WZ (trade name, Kao) previously adjusted to a 20% aqueous solution. A monomer emulsion consisting of 180.0 parts (made by company) and 194 parts deionized water was charged. Next, while maintaining the internal temperature of the polymerization vessel at 80 ° C., 4 parts of the monomer emulsion, 5 parts of 5% potassium persulfate aqueous solution, and 10 parts of 2% aqueous sodium hydrogensulfite solution were added. The initial polymerization was started. After 20 minutes, the remaining monomer emulsion was uniformly flowed down over 180 minutes while maintaining the inside of the reaction system at 80 ° C. At the same time, 100 parts of a 5% aqueous potassium persulfate solution and 100 parts of a 2% aqueous sodium hydrogen sulfite solution were allowed to flow uniformly over 180 minutes, and the same temperature was maintained for 60 minutes after completion of the dropwise addition. After cooling the obtained reaction liquid to room temperature, 15 parts of 25% aqueous ammonia was added, and the nonvolatile content was 55%, pH 7.8, viscosity 230 mPa · s, average particle diameter 290 nm, weight average molecular weight 52000, SP value 8.21. An emulsion F with a Tg of 2 ° C. was obtained.

(Production Example 7)
300 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. On the other hand, 550 parts of styrene, 445 parts of 2-ethylhexyl acrylate, 5 parts of acrylic acid, 3 parts of t-dodecyl mercaptan, and Lebenol WZ (trade name, manufactured by Kao Corporation) previously adjusted to a 20% aqueous solution in the dropping funnel 180. A monomer emulsion consisting of 0 parts and 194 parts deionized water was charged. Next, while maintaining the internal temperature of the polymerization vessel at 80 ° C., 4 parts of the monomer emulsion, 5 parts of 5% potassium persulfate aqueous solution, and 10 parts of 2% aqueous sodium hydrogensulfite solution were added. The initial polymerization was started. After 20 minutes, the remaining monomer emulsion was uniformly flowed down over 180 minutes while maintaining the inside of the reaction system at 80 ° C. At the same time, 100 parts of a 5% aqueous potassium persulfate solution and 100 parts of a 2% aqueous sodium hydrogen sulfite solution were allowed to flow uniformly over 180 minutes, and the same temperature was maintained for 60 minutes after completion of the dropwise addition. After cooling the resulting reaction liquid to room temperature, 3 parts of 25% aqueous ammonia was added, 55% non-volatile content, pH 8.2, viscosity 310 mPa · s, average particle diameter 270 nm, weight average molecular weight 59000, SP value 7.98. , Tg-1 ° C. Emulsion G was obtained.

(Production Example 8)
300 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. On the other hand, 470 parts of styrene, 365 parts of butyl acrylate, 150 parts of 2-ethylhexyl acrylate, 15 parts of acrylic acid, 3 parts of t-dodecyl mercaptan, Lebenol WZ (trade name, Kao) previously adjusted to a 20% aqueous solution in the dropping funnel. A monomer emulsion consisting of 180.0 parts (made by company) and 194 parts deionized water was charged. Next, while maintaining the internal temperature of the polymerization vessel at 80 ° C., 4 parts of the monomer emulsion, 5 parts of 5% potassium persulfate aqueous solution, and 10 parts of 2% aqueous sodium hydrogensulfite solution were added. The initial polymerization was started. After 20 minutes, the remaining monomer emulsion was uniformly flowed down over 180 minutes while maintaining the inside of the reaction system at 80 ° C. At the same time, 100 parts of a 5% aqueous potassium persulfate solution and 100 parts of a 2% aqueous sodium hydrogen sulfite solution were allowed to flow uniformly over 180 minutes, and the same temperature was maintained for 60 minutes after completion of the dropwise addition. The obtained reaction solution was cooled to room temperature, 8 parts of 25% aqueous ammonia was added, 55% non-volatile content, pH 8.1, viscosity 280 mPa · s, average particle size 310 nm, weight average molecular weight 62000, SP value 8.3. And an emulsion H of Tg-4 ° C. was obtained.

(Production Example 9)
300 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. On the other hand, 300 parts of styrene, 90 parts of butyl acrylate, 100 parts of 2-ethylhexyl acrylate, 10 parts of acrylic acid, 2 parts of t-dodecyl mercaptan, Levenol WZ (trade name, manufactured by Kao Corporation) previously adjusted to a 20% aqueous solution. ) First stage monomer emulsion consisting of 90.0 parts and 97 parts deionized water was charged. Next, while maintaining the internal temperature of the polymerization vessel at 80 ° C., 8 parts of the above monomer emulsion, 5 parts of 5% aqueous potassium persulfate solution and 10 parts of 2% aqueous sodium hydrogensulfite solution were added, Polymerization was started. After 20 minutes, the remaining monomer emulsion was uniformly added dropwise over 120 minutes while maintaining the inside of the reaction system at 80 ° C. At the same time, 50 parts of a 5% aqueous potassium persulfate solution and 50 parts of a 2% aqueous sodium hydrogen sulfite solution were uniformly added dropwise over 120 minutes, and the temperature was maintained for 60 minutes after completion of the addition.

Next, a dropping funnel comprising 250 parts of styrene, 240 parts of 2-ethylhexyl acrylate, 10 parts of acrylic acid, 2 parts of t-dodecyl mercaptan, 90.0 parts of Lebenol WZ previously adjusted to a 20% aqueous solution and 97 parts of deionized water. The second-stage monomer emulsion was charged and dropped uniformly over 120 minutes. At the same time, 50 parts of a 5% potassium persulfate aqueous solution and 50 parts of a 2% sodium hydrogen sulfite aqueous solution were uniformly added dropwise over 120 minutes, and the same temperature was maintained for 90 minutes after the addition was completed to complete the polymerization. After cooling the obtained reaction liquid to room temperature, 10 parts of 25% aqueous ammonia was added, 55% non-volatile content, pH 8.3, viscosity 280 mPa · s, average particle diameter 250 nm, weight average molecular weight 54000, first stage SP. Emulsion I having a value of 8.00, a second stage SP value of 8.11, a first stage Tg of 15 ° C., a second stage of Tg of −7 ° C., and a total Tg of 3 ° C. was obtained.

(Examples 1-8, Comparative Examples 1 and 2)
As shown in Table 1, two types of emulsions were mixed and further blended as follows to obtain a damping material composition, and the damping property of the damping material coating film was evaluated by the following test method. The results are shown in Table 1.
Mixed emulsion 359 parts Calcium carbonate (NN # 200 ^{* 1} ) 620 parts Dispersant (Aquaric DL-40S ^{* 2} ) 6 parts Thickener (Acryset WR-650 ^{* 3} ) 4 parts Defoamer (Nopco 8034L ^{* 4)} ) 1 part foaming agent (F-30 ^{* 5} ) 6 parts * 1: Nitto Flour Industry Co., Ltd. filler * 2: Nippon Shokubai Co., Ltd. polycarboxylic acid type dispersant (active ingredient 44%)
* 3: Nippon Shokubai Co., Ltd. alkali-soluble acrylic thickener (active ingredient 30%)
* 4: Anti-foaming agent manufactured by San Nopco (main component: hydrophobic silicone + mineral oil)
* 5: Matsumoto Yushi Co., Ltd. foaming agent

<Vibration suppression test>
The above damping material composition is applied to a cold rolled steel sheet (SPCC, width 15 mm × length 250 mm × thickness 1.5 mm) at a thickness of 3 mm, dried at 150 ° C. for 30 minutes, and then coated on the cold rolled steel sheet. A damping material coating film having a density of 4.0 kg / m ² was formed. The measurement of damping properties uses the cantilever method (loss coefficient measurement system manufactured by Ono Sokki Co., Ltd.), and the loss coefficient at each temperature (20 ° C, 40 ° C, 60 ° C) is determined by the resonance method (3 dB method). It was measured. In addition, the evaluation of the vibration damping performance was performed based on the total loss coefficient (total of the loss coefficients at 20 ° C., 40 ° C., and 60 ° C.), and the greater the value of the total loss coefficient, the better the vibration damping performance.

From the results of Examples 1 to 8 and Comparative Examples 1 and 2, among the polymerization components contained in the emulsion for vibration damping materials, when at least one of the differences in SP value of each polymerization component is 0.2 or more, all It was found that any combination of the polymerization components exhibited an advantageous effect in damping properties compared to the case where the difference in SP value was less than 0.2. Although the difference between this example and the comparative example appears slightly in terms of numerical values, it is a significantly large difference as a loss coefficient representing vibration damping properties. In the above examples, an acrylic copolymer is used as a polymerization component, but there is a sufficient difference in SP value between any combination of the polymerization components constituting the emulsion for vibration damping materials. In this case, the compatibility between the polymerization components becomes low and interphase friction occurs, so it is estimated that this frictional force converts the kinetic energy due to vibration into thermal energy, and exhibits excellent damping properties. The mechanism is the same regardless of the monomer component of the polymerization component that constitutes the emulsion for vibration damping materials, so from the results of the above examples and comparative examples, the technical scope of the present invention, It can be said that the present invention can be applied in various forms disclosed in the present specification and can exhibit advantageous effects.

Claims (8)

An emulsion for vibration damping material obtained by mixing two or more kinds of polymers,
The respective polymers are unrealized one or more polymerizable components are those obtained by emulsion polymerization,
The emulsion contains at least one polymer having a core / shell structure containing two or more polymerization components and another polymer, and the SP value of each polymerization component of the polymer having the core / shell structure and the other polymers. At least one of the differences from the SP value of the polymerization component is 0.2 or more, or contains at least two polymers having a core / shell structure including two or more polymerization components, and the at least two core / shells Among the polymers having a structure, the SP value difference between the polymerization component forming the core part of one kind of polymer and the polymerization component forming the core part of another kind of polymer, the core part of one kind of polymer is SP value difference between a polymerization component to be formed and a polymerization component to form a shell portion of another polymer, or a polymerization component to form a shell portion of one polymer and another polymer Shell part SP value difference between the polymerization component formed, either emulsion for vibration damping materials, wherein the difference in the SP value is 0.2 or more. The emulsion for vibration damping materials according to claim 1 , wherein the emulsion has a difference in SP value of each polymerization component of 0.2 or more. At least one of the polymerization components has a glass transition temperature of −20 to 0 ° C. and a weight average molecular weight of 20,000 to 400,000, and at least one other polymerization component has a glass transition temperature of 0 to 30 ° C. and a weight average. The emulsion for vibration damping materials according to claim 1 or 2 , wherein the molecular weight is 20,000 to 400,000. The polymer having a core / shell structure is characterized in that a difference in glass transition temperature (Tg) between a monomer component forming a core portion and a monomer component forming a shell portion is 10 to 60 ° C. The emulsion for vibration damping materials according to any one of claims 1 to 3. 5. The damping material according to claim 1, wherein the two or more types of polymers have a Tg difference of 10 to 60 ° C. between a polymer having the highest Tg and a polymer having the lowest Tg. Emulsion. The polymerization component is characterized in that the content of an unsaturated monomer having an aromatic ring as a monomer component as a raw material is 10 to 80% by mass with respect to 100% by mass of all monomer components. The emulsion for vibration damping materials according to any one of claims 1 to 5. A damping material composition comprising the emulsion for damping material according to any one of claims 1 to 6 , a pigment, a foaming agent, and a thickener, and having a non-volatile content of 80% by mass or more. A vibration-damping material coating film obtained by baking the vibration-damping material composition according to claim 7 at 100 to 150 ° C, wherein the film thickness of the coating film is 2 to 5 mm. Shaking material coating.