JP5889069B2 - Emulsion resin composition for damping material - Google Patents

Description

  The present invention relates to an emulsion resin composition for damping material.

  The damping material is used to prevent vibration and noise in various structures and to keep quietness. Such vibration damping materials are widely used in automobile interior floors, railway vehicles, ships, aircraft, electrical equipment, building structures, construction equipment, and the like.

  As a material used for a vibration damping material, a molded body using a material having vibration absorption and sound absorption is known. However, when the shape of the vibration or sound generation location is complicated, it may be difficult to form the shape according to the vibration generation location, and it may be difficult to exhibit vibration damping properties.

  On the other hand, various methods for improving workability and sufficiently exhibiting vibration damping properties even in places where the shape is complicated have been studied. For example, an asphalt sheet containing inorganic powder is used under the indoor floor of an automobile, etc., and corresponds to a place having a complicated shape. However, there is a need to heat-seal and there is a problem in workability, and it is also difficult to treat the waste material generated when the sheet is cut.

  On the other hand, by applying a resin composition having vibration damping properties to form a film, it is possible to cope with a complex shape location, improve workability, and improve fuel efficiency by reducing weight. It is considered. As such an example, a nonionic resin is added to a resin composition containing a curable monomer / oligomer and a polymerization initiator in a styrene-diacrylate resin (Patent Document 1) or an unsaturated carboxylic acid monomer. (Patent document 2) etc. which mix | blended these are known.

JP 2009-114231 A JP 2009-270063 A

  However, in the case of these resins, sufficient vibration damping properties may not be obtained.

  Therefore, an object of the present invention is to obtain a coatable resin composition that can sufficiently obtain vibration damping properties.

  The present invention is an emulsion comprising an emulsion copolymer having a structural unit derived from (A) a vinyl ester and (B) a (meth) acrylic monomer and an emulsifier, and the weight average molecular weight of the emulsion copolymer Is 50,000 or more and 500,000 or less, the loss tangent (tan δ) obtained by dynamic viscoelasticity measurement of the obtained dried film is 2.0 or more, and the peak temperature position of this loss tangent is 0. By using an emulsion resin composition for a vibration damping material having a temperature of not lower than 80 ° C. and not higher than 80 ° C., the above problem has been solved.

  Since the emulsion resin composition for a vibration damping material according to the present invention uses a copolymer resin having a specific composition, a high tan δ can be obtained. By using a resin having a high tan δ, the vibration damping property is improved, and the vibration damping property of the resulting resin composition is improved.

The present invention will be described in detail below.
The emulsion resin composition for a vibration damping material according to the present invention includes a vinyl ester (hereinafter sometimes referred to as “component (A)”) and a (meth) acrylic monomer (hereinafter referred to as “component (B)”). It is an emulsion containing an emulsion copolymer having a derived structural unit and an emulsifier.
In the present specification, the expression “(meth) acryl” means “acryl or methacryl”.

[(A) component]
The component (A) according to the present invention, that is, vinyl ester, refers to an ester compound having a vinyl group. For example, vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, vinyl versatate, diethyl maleate, maleate Examples include dibutyl acid and vinyl (meth) acrylate.

[Component (B)]
The component (B) according to the present invention, that is, the (meth) acrylic monomer is a monomer having a (meth) acrylic group. As this monomer, (meth) acrylic acid alkyl ester having no polar functional group described later, and (meth) acrylic having a polar functional group such as a hydroxyl group, a carboxyl group, an ether group, a nitrile group, and an amide group And monomers.

  Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, (meth ) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, s-pentyl (meth) acrylate, 1-ethylpropyl (meth) acrylate, ( 2-methylbutyl (meth) acrylate, isopentyl (meth) acrylate, t-pentyl (meth) acrylate, 3-methylbutyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, (meth) 2-methylpentyl acrylate, 4-methylpentyl (meth) acrylate, (meth) acrylic 2-ethylbutyl, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, 2-heptyl (meth) acrylate, 3-heptyl (meth) acrylate, octyl (meth) acrylate, (Meth) acrylic acid 2-octyl, (meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid isooctyl, (meth) acrylic acid nonyl, (meth) acrylic acid 3,3,5-trimethylhexyl, (meth) acrylic Decyl acid, undecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, docosyl (meth) acrylate, (meth) acrylic acid Tetracosyl, methyl cyclohexyl (meth) acrylate, (meth) a Acrylic acid isobornyl (meth) norbornyl acrylate, benzyl (meth) acrylate, and (meth) phenethyl acrylate. Among these, (meth) acrylic acid alkyl esters having 1 to 24 carbon atoms in the alkyl group, particularly (meth) acrylic acid alkyl esters having 1 to 8 carbon atoms in the alkyl group are preferable.

  Examples of the (meth) acrylic monomer having a hydroxyl group include hydroxylethyl (meth) acrylate, 2-hydroxyisopropyl (meth) acrylate, hydroxybutyl (meth) acrylate, ethylene glycol mono (meth) acrylate, and glycerin. Examples include mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, and polypropylene glycol mono (meth) acrylate.

  Examples of the (meth) acrylic monomer having a carboxyl group (hereinafter sometimes referred to as “carboxyl group-containing (meth) acrylic monomer”) include (meth) acrylic acid. .

  Examples of the (meth) acrylic monomer having an ether group include glycerin monoallyl ether, trimethylolpropane monoallyl ether, allyl alcohol, and the like.

  Examples of the (meth) acrylic monomer having a nitrile group or an amide group include (meth) acrylonitrile, (meth) acrylamide and the like.

[Other monomers]
Moreover, in addition to said (A) component and (B) component, the other monomer which has a polymerizable double bond may be included. Examples of such other monomers include styrene derivatives, vinyl ether monomers, (meth) acrylic acid esters, acrylic compounds other than (meth) acrylic acid, and carboxyl group-containing polymerizable monomers. .

  Examples of the styrene derivative include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene and the like. Furthermore, specific examples of the vinyl ether monomer include vinyl methyl ether and vinyl cyclohexyl ether.

  The carboxyl group-containing polymerizable monomer means a polymerizable monomer other than the above-described carboxyl group-containing (meth) acrylic monomer containing a carboxyl group. Examples thereof include itaconic acid, crotonic acid, maleic acid or its monoester, fumaric acid or its monoester, 2-acryloyloxypropionic acid, and the like.

[Emulsion polymerization]
The emulsion composition for a vibration damping material according to the present invention is obtained by emulsion polymerization of the component (A) and the component (B) in an aqueous medium. This emulsion polymerization is a method of polymerizing the component (A) and the component (B) by a conventional method using a predetermined emulsifier, for example, the polymerization in a reaction vessel charged with an appropriate amount of water or the emulsifier in advance. A component, a polymerization initiator, a chain transfer agent, and the like are charged all at once, divided or continuously, and polymerized under a predetermined reaction condition in an emulsified state while stirring.

As said (B) component, it is preferable that the emulsion composition for damping materials obtained contains the monomer which has the structural unit of the following (B1) or (B2).
(B1): A structural unit derived from the component (B) in the emulsion copolymer, wherein the structural unit includes a structural unit derived from a carboxyl group-containing (meth) acrylic monomer.
(B2): In addition to the structural unit derived from the component (B) in the emulsion copolymer, the structural unit derived from the carboxyl group-containing polymerizable monomer (however, the structural unit corresponding to the above (B1) is excluded. ).

  Examples of the component (B) that forms such a structural unit (B1) include the carboxyl group-containing (meth) acrylic monomers. Examples of the polymerizable monomer that forms the structural unit (B2) include the carboxyl group-containing polymerizable monomers described above.

  In addition, the content ratio of the component (A) and the component (B) constituting the emulsion copolymer in the emulsion composition for vibration damping material obtained is a weight ratio when the total of both is 100 parts by weight, (A) / (B) is preferably 99.5 / 0.5 or less, and preferably 95.0 / 5.0 or less. On the other hand, the lower limit of this weight ratio is preferably 20/80, and preferably 67/33. By satisfying this range, it is possible to perform the polymerization stably and to exhibit the characteristics that an aqueous dispersion having a high tan δ can be obtained.

  When the emulsion copolymer has a structural unit having a carboxyl group, the content ratio of the structural unit having a carboxyl group is preferably 0.5% by weight or more and 1% by weight or more based on the whole of the emulsion copolymer. Is preferred. On the other hand, the upper limit of the content ratio is preferably 7% by weight, and preferably 5% by weight. By satisfying this range, it is possible to perform the polymerization stably and to exhibit the characteristics that an aqueous dispersion having a high tan δ can be obtained.

  The concentration of the monomer mixture during the emulsion polymerization is preferably 15 to 60% by weight, and preferably 30 to 50% by weight. Within this range, the viscosity of the resulting polymer aqueous dispersion is low, which is preferable from the viewpoint of handleability.

  As the polymerization initiator, generally used radical polymerization initiators can be used, and typical examples thereof include persulfates such as ammonium persulfate and potassium persulfate, 2,2-azobisisobutyronitrile, azobiscyano. Azo compounds such as valeric acid, 2,2-azobis (2,4-dimethyl) valeronitrile, peroxides such as t-butylhydroxyl peroxide, benzoyl peroxide, lauroyl peroxide, or radical generators thereof Examples thereof include redox initiators combined with alcorbic acid, sodium bisulfite, potassium bisulfite, Rongalite (sodium formaldehyde sulfoxylate) and the like. These may be used alone or in combination of two or more. The amount of the polymerization initiator used is preferably 0.01 to 3 parts by weight with respect to 100 parts by weight of the monomer mixture.

  The reaction temperature of the emulsion copolymerization reaction is preferably 20 to 95 ° C., and the reaction time is preferably 2 to 8 hours.

  Various known emulsifiers can be used as the emulsifier. Examples of the emulsifier include an anionic emulsifier, a cationic emulsifier, a nonionic emulsifier, and a zwitterionic emulsifier. Examples of the anionic emulsifier include potassium oleate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium alkanesulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, polyoxyethylene alkylether sodium sulfate, polyoxyethylene alkylallyl. Examples thereof include sodium ether sulfate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl allyl ether phosphate, and the like.

Examples of the cationic emulsifier include stearylamine hydrochloride, lauryltrimethylammonium chloride, and trimethyloctadodecylammonium chloride.
Furthermore, examples of the nonionic emulsifier include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oxypropylene block polymer, polyethylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester and the like.
Furthermore, examples of amphoteric emulsifiers include lauryl betaine and lauryl dimethylamine oxide.

  Among these, the use of a composite emulsifier of the anionic emulsifier and the nonionic emulsifier is advantageous in that it can achieve both good particle stability with the anionic emulsifier and excellent pigment dispersibility with the nonionic emulsifier. can do.

  The amount of the emulsifier used is preferably 1 part by weight or more and preferably 2 parts by weight or more with respect to 100 parts by weight of the monomer mixture. If it is less than 1 part by weight, the stability of the aqueous dispersion produced during emulsion polymerization may be insufficient. On the other hand, the upper limit of the amount used is preferably 8 parts by weight, and preferably 5 parts by weight. If it is more than 8 parts by weight, the water resistance of the resulting film may be deteriorated.

[Properties of emulsion resin composition for damping material]
The weight average molecular weight of the emulsion copolymer constituting the emulsion resin composition for a vibration damping material according to the present invention needs to be 50,000 or more, and preferably 100,000 or more. When the weight average molecular weight is less than 50,000, the heat resistance is lowered, and there may be a problem that the coating drips or flows when the coating film is dried. On the other hand, the upper limit of the weight average molecular weight is required to be 500,000, preferably 400,000. If it is greater than 500,000, the surface may be cracked when cracked.

  Furthermore, the glass transition temperature (Tg) of the emulsion copolymer constituting the emulsion resin composition for vibration damping materials according to the present invention is preferably −20 ° C. or higher, and preferably 0 ° C. or higher. If it is lower than −20 ° C., the vibration damping property on the high temperature side tends to be insufficient. On the other hand, the upper limit of the glass transition temperature is preferably 40 ° C, and preferably 25 ° C. If it is higher than 40 ° C., there may be a problem that the vibration damping property on the low temperature side is insufficient.

By the way, the emulsion resin composition for a vibration damping material according to the present invention has a vibration damping property, that is, a property that absorbs vibration and prevents transmission of vibration. The loss tangent (tan δ) obtained by dynamic viscoelasticity measurement The higher the value, the higher the damping performance. This is because the high loss tangent (tan δ) indicates the liquid property of the material, that is, the ability to absorb vibration and convert it into heat.
In addition, a dynamic viscoelasticity measurement can be measured using dynamic viscoelasticity measuring apparatuses (rheometer), such as Rheogel-E series (made by UBM), for example.

  With respect to the dry film obtained from the emulsion resin composition for vibration damping material according to the present invention, the loss tangent (tan δ) determined by dynamic viscoelasticity measurement needs to be 2.0 or more, and preferably 2.2 or more. If it is less than 2.0, sufficient vibration damping cannot be obtained. On the other hand, the upper limit of the loss tangent (tan δ) is not particularly limited, but approximately 2.5 is sufficient in consideration of the characteristic value of a vibration damping material that is normally used.

  Furthermore, the peak temperature position of the loss tangent (tan δ) determined by dynamic viscoelasticity measurement for the dry film obtained from the emulsion resin composition for a vibration damping material according to the present invention needs to be 0 ° C. or higher, and is 20 ° C. or higher. Is preferred. If it is lower than 0 ° C., the vibration damping property on the high temperature side tends to be insufficient. On the other hand, the upper limit of the peak temperature position of loss tangent (tan δ) needs to be 80 ° C., and preferably 60 ° C. If it is higher than 80 ° C., there may be a problem that the vibration damping property on the low temperature side is insufficient.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited by a following example, unless the summary is exceeded. First, the evaluation method and the raw materials used will be described.

  First, raw materials and evaluation methods used in the examples will be described.

<Evaluation method>
[Glass transition temperature (Tg)]
The constituent weight fractions of the constituent monomers a, b,... In the copolymer are Wa, Wb,..., And the glass transition temperatures of the homopolymers of the constituent monomers a, b,. ,..., The Tg value of the vinyl polymer as a copolymer was determined by the FOX formula shown below.
1 / Tg = Wa / Tga + Wb / Tgb +

[Average particle size]
The average particle diameter was measured using a dynamic light scattering particle size distribution analyzer (Otsuka Electronics Co., Ltd .: ELS-8000).

[Non-volatile content]
About 1 g of the polymer aqueous dispersion was precisely weighed and dried in a hot air circulating dryer at 105 ° C. for 3 hours, then allowed to cool in a desiccator, and the weight was measured. The nonvolatile content was calculated according to the following formula.
Nonvolatile content (%) = (weight of sample after drying / weight of sample before drying) × 100

[viscosity]
1 kg of an aqueous polymer dispersion at 25 ° C. was placed in a 1 liter glass beaker, and measured using a Brookfield viscometer (manufactured by Tokyo Keiki Co., Ltd., type B viscometer, type BM) at a rotor rotation speed of 60 rpm. .

[PH]
About 500 ml of the polymer aqueous dispersion was taken so as not to contain bubbles, and measured at a test temperature of 25 ° C. ± 1 ° C. by attaching a glass electrode specified in JIS Z 8805 to a pH meter specified in JIS Z 8802. (According to JIS K 6828).

[Weight average molecular weight (Mw)]
The obtained polymer was dissolved in tetrahydrofuran, and the weight average molecular weight in terms of polymethyl methacrylate was calculated using gel per emission chromatography.

[Tan δ and its peak temperature]
The aqueous polymer dispersion was coated on a Teflon (trade name) plate to a thickness of 750 μm to form a film, dried at 60 to 90 ° C. for 1 day on the front and 1 day on the back, and then measured for dynamic viscoelasticity. The tan δ of the film was measured using an apparatus Rheogel E-4000 (manufactured by UBM).

(Gel fraction)
About 20 mg of the emulsion polymer was precisely weighed, 20 ml of tetrahydrofuran (THF) was added thereto, and allowed to stand at room temperature for 24 hours, and then the residue filtered through a filter with a pore size of 0.45 μm was dried at 105 ° C. for 3 hours. The gel fraction was calculated by measuring the amount of recovered insoluble matter.

<Raw materials>
[(A) component]
Vinyl acetate: manufactured by Nippon Synthetic Chemical Industry Co., Ltd., hereinafter abbreviated as “VAc”.
[Component (B)]
・ Butyl acrylate: manufactured by Mitsubishi Chemical Corporation, hereinafter abbreviated as “BA”.
-Ethyl acrylate: Mitsubishi Chemical Corporation, hereinafter abbreviated as "EA".
・ Methyl methacrylate: manufactured by Mitsubishi Rayon Co., Ltd., hereinafter abbreviated as “MMA”.
Acrylic acid: manufactured by Mitsubishi Chemical Corporation, hereinafter abbreviated as “AA”.
Methacrylic acid: Mitsubishi Rayon Co., Ltd., hereinafter abbreviated as “MAA”.
Itaconic acid: manufactured by Iwata Chemical Co., Ltd., hereinafter abbreviated as “IA”.
[Other monomers]
Acrylamide: manufactured by Diaanitrix Co., Ltd., hereinafter abbreviated as “AAm”.

[emulsifier]
Anionic emulsifier: polyoxyethylene (POE) sodium alkyl ether sulfate, manufactured by Kao Corporation: Latemulu WX, hereinafter abbreviated as “Latemuru WX”.
Reactive anionic emulsifier: alkylallylsulfosuccinic acid sodium salt, manufactured by Sanyo Chemical Co., Ltd .: Eleminol JS-20, hereinafter abbreviated as “JS-20”.
Reactive anionic emulsifier: α-sulfo-ω- (1-alkoxy) methyl-2- (2-propenyloxy) ethoxy-poly-1,2-ethanediyl) ammonium salt, manufactured by ADEKA Corporation: ADEKA rear soap SR-1025, hereinafter abbreviated as “SR-1025”.
Nonionic emulsifier: polyoxyethylene (POE) lauryl ether, manufactured by Kao Corporation: Emulgen 120, hereinafter abbreviated as “Emulgen 120”.

(Examples 1-7 , Reference Examples 1-2, Comparative Examples 1-2)
A 1 L flask equipped with a stirrer, a reflux condenser and a raw material charging port was charged with 150 parts by weight of ion-exchanged water and the emulsifier described in Table 1, and while maintaining the internal temperature at 80 ° C., APS (ammonium persulfate) was used. ) Was added dropwise, and 185 parts by weight of ion-exchanged water and the monomers listed in Table 1 were added dropwise over 4 hours.
After completion of dropping, the mixture was aged for 2 hours while maintaining the internal temperature at 80 ° C. The obtained emulsion was cooled to 30 ° C. to obtain an aqueous polymer dispersion. Each of the above evaluations was performed using the obtained polymer aqueous dispersion. The results are also shown in Table 1.

Claims (6)

(A) An emulsion containing an emulsifier and an emulsion copolymer having a structural unit derived from a vinyl ester and (B) a (meth) acrylic monomer,
When the ratio of the structural unit (A) and the structural unit (B) in the emulsion copolymer is 100 parts by weight of the total of both,
(A) / (B) = 99.5 / 0.5 to 67/33
In the range of
The weight average molecular weight of the emulsion copolymer is 50,000 or more and 500,000 or less,
The loss tangent (tan δ) determined by dynamic viscoelasticity measurement of the obtained dried film is 2.0 or more, and the peak temperature position of this loss tangent is 20 ° C. or more and 60 ° C. or less. Resin composition.   The emulsion resin composition for a vibration damping material according to claim 1, wherein the emulsion copolymer has a glass transition temperature of -20 ° C or higher and 40 ° C or lower. The emulsion copolymer contains a structural unit having a carboxyl group,
And the content ratio is 0.5 to 7 weight% with respect to the said whole emulsion copolymer, The emulsion resin composition for damping materials of Claim 1 characterized by the above-mentioned. The emulsion resin composition for a vibration damping material according to claim 3 , wherein the structural unit having a carboxyl group is a structural unit derived from acrylic acid or methacrylic acid. The structural unit having a carboxyl group is at least one unit selected from the group consisting of itaconic acid, crotonic acid, maleic acid and / or its monoester, fumaric acid and / or its monoester, 2-acryloyloxylpropionic acid. The emulsion resin composition for vibration damping materials according to claim 3 , wherein the emulsion resin composition is a body-derived structural unit. The emulsion resin composition for a vibration damping material according to any one of claims 1 to 5 , wherein the emulsifier is a composite emulsifier of an anionic emulsifier and a nonionic emulsifier.