JP5197111B2 - Damping material composition and damping structure using the same - Google Patents

Description

  The present invention relates to a damping material composition and a damping structure using the same.

  The damping material composition is used in various fields. For example, materials that can absorb displacement and vibration caused by wind and earthquake are used as building skeleton structure forming materials in the building field, and electronic components such as computer disk drives prevent damage or malfunction due to vibration. Therefore, it is protected with a material that absorbs vibration. A damping material composition is usually used as a material that absorbs such displacement and vibration.

  As the damping material composition, rubber-based, silicone-based, acrylic-based resins, and the like have been proposed (for example, Patent Document 1 and Patent Document 2). Acrylic resins are generally suitable for long-term use because they are excellent in weather resistance and heat resistance, but when used as damping material compositions, the damping performance varies greatly depending on the temperature used. That is, there is a problem that the temperature dependency is large.

  As a damping material composition using an acrylic resin, for example, one containing an acrylate polymer having an alkyl group having 14 to 20 carbon atoms (Patent Document 3) or (A) an alkyl having 2 to 20 carbon atoms A base-isolated structure comprising, as a soft plate, a polymer obtained by photopolymerization of an acrylate having a group, (B) natural rubber and / or synthetic rubber, (C) a crosslinking agent, and (D) a photopolymerization initiator (Patent Document 4) ) Is disclosed. In Patent Document 4, it is said that by using an acrylic resin and a natural rubber-based or synthetic rubber-based resin, it is possible to provide a soft plate whose elastic modulus does not change greatly due to a temperature change.

International Publication No. 01/074964 Pamphlet International Publication No. 96/035438 Pamphlet JP-A-11-140216 JP 2001-124124 A

  An object of the present invention is to obtain a vibration damping composition having improved temperature dependency. The conventional damping material composition has a problem that the loss tangent tan δ in the high temperature and low frequency region (for example, measurement temperature 40 ° C., frequency 0.1 Hz) is remarkably lowered and the damping performance is inferior. According to the damping material composition of the invention, it can be used even in a high temperature low frequency region. The damping material composition is, for example, a damping material that absorbs shock displacement or vibration such as wind and earthquake of building skeleton structure forming materials in the building field, or a damping material that absorbs vibration of a computer disk drive. Useful as.

  That is, the present invention provides (A) a (meth) acrylic monomer mixture comprising 92 to 95% by mass of a (meth) acrylic monomer having an alkyl group having 14 to 22 carbon atoms and 5 to 8% by mass of a carboxyl group-containing monomer. And (B) 2 to 40 parts by mass of a saturated polyolefin and / or saturated polyolefin block and an aromatic vinyl monomer block with respect to 100 parts by mass of the (meth) acrylic monomer mixture. The present invention provides a vibration damping composition containing a block copolymer.

  Furthermore, the present invention provides a damping structure having a rigid sheet sandwiched between the damping material compositions.

  The damping material composition of the present invention has low temperature dependence of the shear storage modulus and loss tangent obtained by dynamic viscoelasticity measurement. Therefore, the damping material composition has high damping in a wide temperature range where the damping material composition is used. The performance can be maintained.

  Details of the present invention will be described below.

The (meth) acrylic monomer having an alkyl group having 14 to 22 carbon atoms used in the present invention (hereinafter referred to as C14-22 monomer) is generally represented by the formula CH ₂ = CR ¹ COOR ² (wherein R ¹ Is hydrogen or a methyl group, and R ² is an alkyl group. Examples of the C14-22 monomer include isostearyl (meth) acrylate, cetyl (meth) acrylate, n-stearyl (meth) acrylate, n-behenyl (meth) acrylate, isomyristyl (meth) acrylate, and isopalmityl (meth) acrylate. Etc. can be used. As the alkyl group of the C14-22 monomer, a branched one can also be used. When the branched alkyl group is used, crystallization of the vibration damping composition at a low temperature can be suppressed.

  Depending on the purpose, one or more C14-22 monomers can be used to obtain the desired properties. In order to suppress crystallization of the vibration damping composition at a low temperature, 50% by mass or more of the C14-22 monomer is preferably a (meth) acrylic monomer having a branched alkyl group. In the present specification, “(meth) acryl” means acryl or methacryl.

  Examples of the carboxyl group-containing monomer include unsaturated monocarboxylic acids (for example, acrylic acid, methacrylic acid, etc.), unsaturated dicarboxylic acids (for example, maleic acid, itaconic acid, etc.), ω-carboxypolycaprolactone monoacrylate, phthalic acid monohydroxy Ethyl (meth) acrylate, β-carboxyethyl acrylate, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, or the like can be used.

  The (meth) acrylic monomer mixture includes a C14-22 monomer and a carboxyl group-containing monomer, and the blending is 92 to 95% by mass of the C14-22 monomer and 5 to 8% by mass of the carboxyl group-containing monomer. . When the amount of the carboxyl group-containing monomer is less than 5% by mass, the shear storage elastic modulus G ′ of the vibration damping composition becomes small and the cohesive force is lowered. Further, the loss tangent tan δ is also reduced and the vibration damping performance is poor. On the other hand, when the amount of the carboxyl group-containing monomer is larger than 8% by mass, the ratio G′0 / G′40 of the shear storage modulus at 0 ° C. and 40 ° C. of the vibration damping composition exceeds 15.0. Therefore, there is a problem that the temperature dependency of the damping performance of the damping material composition is increased.

  Saturated polyolefin is polyolefin which has substantially no carbon-carbon double bond or triple bond. Of the carbon-carbon bonds contained in the saturated polyolefin, 90% or more are single bonds. Examples of saturated polyolefins include polyethylene, polybutene, polypropylene, polyisobutylene, poly α-olefin, ethylene / propylene copolymer, ethylene / α-olefin copolymer, propylene / α-olefin copolymer, hydrogenated polybutadiene, etc. Is mentioned. These may be used alone or in combination of two or more.

An amorphous polymer can also be used for the saturated polyolefin. An amorphous polymer refers to a polymer that has a very low degree of crystallinity or cannot be in a crystallized state. For amorphous polymers, the glass transition point is measured, but the melting point is not measured. When an amorphous polymer is used, the shear storage modulus G ′ of the vibration damping composition at 0 to 40 ° C. is adjusted to 1.5 × 10 ^{4 to} 5.0 × 10 ⁶ Pascal (Pa). And the adhesion to the adherend is excellent.

  A block copolymer containing a saturated polyolefin block and an aromatic vinyl monomer block (hereinafter referred to as a block copolymer) is composed of a polyolefin block having substantially no carbon-carbon double bond or triple bond, and an aromatic vinyl. And a block made of a monomer. Of the carbon-carbon bonds contained in the saturated polyolefin block, 90% or more are single bonds. Examples of the aromatic vinyl monomer include styrene, p-methylstyrene, α-methylstyrene, and indene. These may be used alone or in combination of two or more. Examples of the block copolymer include a styrene-ethylene-propylene-styrene block copolymer, a styrene-ethylene-propylene block copolymer, and a styrene-ethylene-butylene-styrene block copolymer.

As the saturated polyolefin block, an amorphous one can be used. When an amorphous material is used, the shear storage modulus G ′ of the vibration damping composition at 0 to 40 ° C. is adjusted to 1.5 × 10 ^{4 to} 5.0 × 10 ⁶ Pascal (Pa). And adhesion to the adherend is excellent.

  The blending ratio of the saturated polyolefin and / or the block copolymer can be 2 to 40 parts by mass with respect to 100 parts by mass of the (meth) acrylic monomer mixture. If it is less than 2 parts by mass, it will be difficult to obtain a damping material composition having a small temperature dependency. If it exceeds 40 parts by mass, the weather resistance and heat resistance will be poor, and the reliability of long-term use will be low. This is because the adhesion to the adherend also deteriorates.

  The weight average molecular weight of the saturated polyolefin and the block copolymer may be in the range of 10,000 to 2,000,000. This is because when the molecular weight is decreased, the elastic modulus tends to decrease, the heat resistance is poor, and the reliability of long-term use may be lowered.

  Examples of a method for polymerizing a (meth) acrylic monomer mixture containing a C14-22 monomer and a carboxyl group-containing monomer include known polymerization methods such as solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization. it can. After polymerizing a C14-22 monomer and a carboxyl group-containing monomer, a vibration damping composition can be obtained by adding a saturated polyolefin and / or block copolymer, but a saturated polyolefin and / or block copolymer. In the presence of C14-22 monomer and a carboxyl group-containing monomer can be polymerized.

  In order to obtain a damping material composition having a large thickness, it is preferable to use photopolymerization. In this case, polymerization is carried out by containing a photopolymerization initiator and irradiating light. In the following, the polymerization method will be described taking photopolymerization with ultraviolet rays as an example.

  A C14-22 monomer, a carboxyl group-containing monomer and a photopolymerization initiator are placed in a suitable reaction vessel, and a crosslinking agent or other additive is added as necessary, and polymerization is performed by irradiation with a suitable amount of light such as ultraviolet rays. Reaction is performed to obtain a vibration damping composition. The reaction is usually performed in an inert atmosphere such as nitrogen.

  As a photopolymerization initiator, for example, benzoin such as benzoin, benzoin methyl ether, benzoin isopropyl ether, and α-acryl benzoin, 2,2-dimethoxy-1,2-diphenylethane-1-one (manufactured by Ciba Specialty Chemicals) Irgacure 651), 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184 manufactured by Ciba Specialty Chemicals), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Darocure 1173 manufactured by Ciba Specialty Chemicals) ), 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (Irgacure 2959, manufactured by Ciba Specialty Chemicals), 2-methyl-1 [4 -(Methylthio) phenyl] -2-mo Ruforinopropan-1-one (Irgacure 907 manufactured by Ciba Specialty Chemicals), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (Irgacure 369 manufactured by Ciba Specialty Chemicals) Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (Irgacure 819, manufactured by Ciba Specialty Chemicals) Darocur, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (produced by Ciba Specialty Chemicals) (Trademark) TPO), 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propyl) -benzyl] -phenyl} -2-methyl-propan-1-one (Ciba Specialty Chemicals) Irgacure 127), 2-dimethylamino 2- (4- methyl-benzyl) - 1 - (4-morpholin-4-yl-phenyl) - - butan-1-one (Ciba Specialty Chemicals Inc. Irgacure 379) and the like can be exemplified.

  A photoinitiator is mix | blended by 0.01-5.0 mass parts with respect to 100 mass parts of (meth) acrylic-type monomer mixtures containing a C14-22 monomer and a carboxyl group-containing monomer. If the blending amount is less than 0.01 parts by mass, the photopolymerization initiator is consumed at the initial stage of polymerization by light energy, so that unreacted monomers are likely to remain and the cohesive force is reduced. On the other hand, when the amount exceeds 5.0 parts by mass, the polymerization reaction rate increases, but the residual odor accompanying decomposition of the photopolymerization initiator becomes severe, and the dispersion of the molecular weight of the resulting polymer increases and the adhesive performance also decreases. To do.

  An ultraviolet lamp is usually used for light irradiation. As the ultraviolet lamp, a lamp having an emission spectrum distribution at a light wavelength of 300 to 400 nm is used. Examples thereof include a chemical lamp, a black light lamp (manufactured by Toshiba Denshi Co., Ltd.), a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, and a metal halide lamp. And a microwave-excited mercury lamp.

  The photopolymerization of the C14-22 monomer and the carboxyl group-containing monomer may be performed in the presence of a saturated polyolefin and / or a block copolymer. In this case, a photopolymerization initiator and, if necessary, other additives are added to a mixture of a C14-22 monomer, a carboxyl group-containing monomer, a saturated polyolefin and / or a block copolymer, and then photopolymerization is performed. .

  Moreover, although light irradiation may be performed at once, it may be performed in two or more stages. For example, a mixture containing a polymerization initiator is irradiated with light and partially reacted to obtain a polymerizable prepolymer syrup having an appropriate viscosity. Then, an additional monomer is put in a syrup, and this mixture is introduced between two exfoliated polyethylene terephthalate (PET) base materials, and then irradiated with light to form a vibration damping composition.

  In order to improve mechanical properties such as shear strength and thermal properties such as heat resistance of the obtained vibration damping composition, a crosslinking agent can also be used. As the crosslinking agent, a crosslinking monomer such as a polyvalent acrylate can be used. Examples of the polyvalent acrylate that can be used as the crosslinking agent include 1,6-hexanediol diacrylate.

  The damping material composition may contain a tackifying resin in order to impart a high level of adhesive strength. Examples of such tackifying resins include rosin resins, modified rosin resins (hydrogenated rosin resins, disproportionated rosin resins, polymerized rosin resins, etc.), terpene resins, terpene phenol resins, aromatic modified terpene resins, There are C 5 and C 9 petroleum resins, coumarone resins and the like.

  As long as the effect of the present invention is not impaired, one or more of other additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, a plasticizer, a lubricant, an antistatic agent, a flame retardant, and a filler are added. You may add to a damping material composition.

  The vibration damping composition of the present invention is characterized in that crystallization does not occur at 0 ° C. or higher. When crystallization occurs at 0 ° C. or higher, the temperature dependence of the vibration damping performance of the vibration damping composition increases. A damping material composition in which crystallization does not occur at 0 ° C. or higher is not observed at 0 ° C. or higher when a storage elastic modulus G ′ (Pa) is rapidly increased when the crystallization measurement described below is performed. Refers to the composition. The crystallization measurement was performed using an advanced rheometric expansion system (ARES) manufactured by Rheometric Scientific, with a cooling rate of 5.0 ° C./min from a measurement start temperature of 60 ° C. to −60 ° C. in a shear mode at a frequency of 1.0 Hz. This is performed by measuring the storage elastic modulus G ′ (Pa) every 12 seconds and plotting G ′ at each temperature. When the damping material composition exhibits crystallinity, a rapid increase in G ′ is observed from the crystallization temperature (for example, Example 26 and Comparative Example 12 in FIG. 1).

The vibration damping composition of the present invention preferably exhibits the following characteristics at 0 to 40 ° C. in the shear mode dynamic viscoelasticity measurement in the frequency range of 0.1 to 10.0 Hz.
(1) The ratio (G′0 / G′40) of the shear storage modulus G′0 at 0 ° C. and the shear storage modulus G′40 at 40 ° C. is 15.0 or less.
(2) The shear storage modulus G ′ is 1.5 × 10 ⁴ Pascal (Pa) or more and 5.0 × 10 ⁶ (Pa) or less.
(3) The loss tangent tan δ is 0.5 or more.

When G′0 / G′40 exceeds 15.0, the temperature dependency of the vibration damping performance increases. When G ′ is less than 1.5 × 10 ⁴ (Pa), the cohesive force of the vibration damping material composition is low. When G ′ exceeds 5.0 × 10 ⁶ (Pa), the tackiness decreases and the adhesion to the adherend becomes too low, and when tan δ is less than 0.5, the vibration absorption is inferior.

  The dynamic viscoelasticity measurement was performed using an advanced rheometric expansion system (ARES) manufactured by Rheometric Scientific, and at a frequency of 0.1, 0.3, 1.0, 3.0, and 10.0 Hz, respectively. The shear storage modulus G ′ and loss tangent tan δ at 10, 20, 30, and 40 ° C. are measured in the shear mode.

The damping material composition of the present invention preferably has a shear strain at break of 600% or more when a shear deformability test is performed. The shear deformability test is performed under the following measurement conditions in accordance with JIS K6868-2 (1999).
Measurement conditions / Measurement test sample shape: 20 mm × 20 mm × 1.2 mm size / Substrate: Stainless steel plate (SUS304) 25 mm × 100 mm × 1.5 mm size / Measurement temperature: 20 ° C.
・ Tensile speed: 300mm / min

The shear stress at break (N / cm ² ) is a value obtained by dividing the load (N) when the measurement test sample is broken by the adhesion area (20 mm × 20 mm) of the measurement test sample. The shear strain at break is a value obtained by dividing the displacement (mm) until the measurement test sample is broken by the thickness (1.2 mm) of the measurement test sample.

  The damping material composition may be used as a damping structure in which a rigid sheet is sandwiched between a plurality of damping material compositions. By using a restraint structure in which the damping material composition is laminated with one or more rigid sheets, damping properties can be further enhanced.

  As the rigid sheet, a metal plate or a polymer resin plate can be used. As a metal plate, what consists of iron materials, such as a steel plate, stainless steel, an aluminized steel plate, a galvanized steel plate, an epoxy coating steel plate, and the thing which consists of metal materials, such as zinc, aluminum, and titanium, etc. are mentioned. Moreover, as a polymer resin board, the plate-shaped body which consists of raw materials, such as a fiber reinforced plastic (FRP), a vinyl chloride board, polyethylene, a polypropylene, a polycarbonate, an acryl, is mentioned. Further, the metal plate and the polymer resin plate may be used in combination.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not limited to these.

In Examples and Comparative Examples, the following abbreviations may be used.
ISA: Isostearyl acrylate (C18 alkyl acrylate) (trade name: NK Ester (trademark) ISA, manufactured by Shin-Nakamura Chemical Co., Ltd.)
2EHA: 2-ethylhexyl acrylate (trade name AEH manufactured by Toa Gosei Co., Ltd.)
AA: Acrylic acid (manufactured by Toa Gosei Co., Ltd.)
TDA: Tridecyl acrylate (trade name SR489, manufactured by Sartomer)
CA: Cetyl acrylate (alkyl acrylate having 16 carbon atoms) (trade name Blemmer (trademark) CA manufactured by NOF Corporation)
STA: n-stearyl acrylate (C18 alkyl acrylate) (trade name STA manufactured by Osaka Organic Chemical Industry Co., Ltd.)
VA: n-behenyl acrylate (C22 alkyl acrylate) (trade name Blemmer (trademark) VA manufactured by NOF Corporation)
IMA: Isomyristyl acrylate (C14 alkyl acrylate) (trade name Light Acrylate (trademark) IM-A manufactured by Kyoeisha Chemical Co., Ltd.)
IPA: Isopalmityl acrylate (C16 alkyl acrylate) (trade name HEDA 16 manufactured by Toho Chemical Industry Co., Ltd.)
HDDA: 1,6-hexanediol diacrylate (trade name Light Acrylate (trademark) 1,6HX-A manufactured by Kyoeisha Chemical Co., Ltd.)
D-TPO: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (trade name Darocur (trademark) TPO manufactured by Ciba Specialty Chemicals)
X1104P: Amorphous polypropylene (trade name Tough Selenium (trademark) X1104P, manufactured by Sumitomo Chemical Co., Ltd., weight average molecular weight 550,000)
Butyl 268: polyisobutylene (manufactured by JSR, weight average molecular weight 480,000)
OP B-10: Polyisobutylene (trade name Oppanol (trademark) B-10, manufactured by BASF, weight average molecular weight 22,500)
OP B-15: polyisobutylene (manufactured by BASF, Opanol ™ B-15, weight average molecular weight 75,000)
OP B-30: polyisobutylene (manufactured by BASF, Opanol ™ B-30, weight average molecular weight 200,000)
OP B-100: polyisobutylene (manufactured by BASF, Opanol ™ B-100, weight average molecular weight 1,100,000)
SPT 2063: Amorphous styrene-ethylene-propylene-styrene block copolymer (trade name SEPTON (trademark) 2063, containing 13 wt% styrene, weight average molecular weight 120,000, manufactured by Kuraray Co., Ltd.)
SPT 1001: Amorphous styrene-ethylene-propylene block copolymer (trade name SEPTON (trademark) 1001, made by Kuraray Co., Ltd., containing 35 wt% styrene, weight average molecular weight 190,000)
SPT 8006: Amorphous styrene-ethylene-butylene-styrene block copolymer (trade name SEPTON (trademark) 8006, containing 33 wt% styrene, weight average molecular weight 340,000, manufactured by Kuraray Co., Ltd.)
D1340K: Styrene-isoprene-styrene block copolymer (trade name, Kraton (trademark) D1340K, manufactured by Kraton Polymers)
SS-9000: Styrene-hydrogenated butadiene copolymer (SODE (trademark) SS9000 manufactured by Asahi Kasei Chemicals Corporation)
DN401: Acrylonitrile-butadiene copolymer (trade name Nipol (trademark) DN401, manufactured by Nippon Zeon Co., Ltd.)

Examples 1 to 4
5 parts by mass of X1104P, 0.1 parts by mass of HDDA, and 0.3 parts by mass of 100 parts by mass of a (meth) acrylic monomer mixture consisting of 95% by mass of ISA and 5% by mass of AA D-TPO was mixed. This mixture is sandwiched between two exfoliated PET films, and irradiated with UV light of 3000 mJ / cm ^{2 with} a fluorescent black light bulb (Sylvania (trademark) F20T12B). 1 damping material composition was obtained.

Dynamic viscoelasticity measurement was performed on the obtained vibration damping composition. The results are shown in Table 1. G ′ is 1.6 × 10 ⁴ to 4.3 × 10 ⁵ (Pa) and has a temperature dependence G′0 / G at a frequency of 0.1 to 10.0 Hz and a temperature range of 0 to 40 ° C. '40 was 4.4 to 6.2, and tan δ was 0.5 to 0.9. In addition, a shear deformability test was performed on the obtained damping material composition. The results are shown in Table 1.

About Examples 2-4, the damping material composition was produced like Example 1 except having changed the compounding quantity of ISA and AA into the value shown in Table 1. FIG. Table 1 shows the results of the dynamic viscoelasticity measurement and shear deformation test. G ′ was in the range of 1.6 × 10 ^{4 to} 2.1 × 10 ⁶ (Pa), the temperature dependency G′0 / G′40 was 15.0 or less, and tan δ was 0.5 or more. Further, the shear strain at break showed 600% or more.

Comparative Examples 1-3
A damping material composition was prepared in the same manner as in Example 1 except that polypropylene (X1104P) was not used and the blending amounts of ISA and AA were changed to the values shown in Table 1. Table 1 shows the results of the dynamic viscoelasticity measurement and shear deformation test.

Examples 5-9
A vibration damping composition was prepared in the same manner as in Example 1 except that various saturated polyolefins or block copolymers were mixed as shown in Table 2 instead of X1104P. Table 2 shows the results of dynamic viscoelasticity measurement and shear deformation test. G ′ was within a range of 1.9 × 10 ^{4 to} 1.3 × 10 ⁶ (Pa), G′0 / G′40 showing temperature dependence was 15.0 or less, and tan δ was 0.5 or more. Further, the shear strain at break showed 600% or more.

Comparative Examples 4-8
A damping material composition was produced in the same manner as in Example 1 except that the type and blending ratio of the mixture were mixed as shown in Table 3. Table 3 shows the results of the respective dynamic viscoelasticity measurements and shear deformability tests. Since SS9000 used in Comparative Example 7 was not a block copolymer with styrene, the temperature dependency of the vibration damping composition was large.

Examples 10-20
A damping material composition was produced in the same manner as in Example 1 except that the types and blending ratios of the mixtures were mixed as shown in Tables 4 and 5. Tables 4 and 5 show the results of the respective dynamic viscoelasticity measurements and shear deformability tests. G ′ was in the range of 1.5 × 10 ^{4 to} 1.3 × 10 ⁶ (Pa), G′0 / G′40 showing temperature dependence was 15.0 or less, and tan δ was 0.5 or more. Further, the shear strain at break showed a sufficient shear deformability of 600% or more. Example 10 was subjected to crystallization measurement, and the results are shown in FIG. No significant increase in G ′ was observed and no crystallization was confirmed.

Examples 21-27
A damping material composition was produced in the same manner as in Example 1 except that the types and blending ratios of the mixtures were mixed as shown in Tables 6 and 7. Tables 6 and 7 show the results of the respective dynamic viscoelasticity measurements and shear deformability tests. Examples 25, 26, and 27 were subjected to crystallization measurement, and the results are shown in FIG. In Examples 25 and 27, no significant increase in G ′ was observed, and no crystallization was confirmed.

In Example 26, a damping material composition was prepared using STA, which is a normal alkyl acrylate having 18 carbon atoms, and crystallization measurement was performed. The results are shown in FIG. A remarkable increase in elastic modulus was observed from −5 ° C., and crystallization occurred, but at 0 to 40 ° C., the elastic modulus G ′ was 1.5 × 10 ^{4 to} 1.1 × 10 ⁶ (Pa) and was dependent on temperature. The sex G′0 / G′40 was 9.3 to 13.7, and tan δ was 0.5 to 0.9. Further, the shear strain at the time of breaking showed a sufficient shear deformability of 821%.

Comparative Examples 9-11
A damping material composition was prepared in the same manner as in Example 1 except that an alkyl acrylate having 13 or less carbon atoms was mixed as shown in Table 8. Table 8 shows the results of the respective dynamic viscoelasticity measurements and shear deformability tests.

Comparative Example 12
A damping material composition was prepared in the same manner as in Example 1 except that VA, which is a normal alkyl acrylate having 22 carbon atoms, was blended as shown in Table 8. Table 8 shows the results of the dynamic viscoelasticity measurement and the shear deformability test. The result of the crystallization measurement is shown in FIG. In the obtained damping material composition, a remarkable increase in G ′ was observed at 13 ° C., and crystallization occurred at 0 ° C. or higher.

The graph of the shear storage elastic modulus G '(Pa) in each temperature in an Example is shown.

Claims (6)

(A) Obtained by polymerizing a (meth) acrylic monomer mixture containing 92 to 95% by mass of a (meth) acrylic monomer having an alkyl group having 14 to 22 carbon atoms and 5 to 8% by mass of a carboxyl group-containing monomer. A polymer obtained,
(B) a block copolymer containing 2 to 40 parts by weight of a saturated polyolefin and / or a saturated polyolefin block and an aromatic vinyl monomer block with respect to 100 parts by weight of the (meth) acrylic monomer mixture;
A damping material composition comprising: a damping material composition, wherein crystallization does not occur at 0 ° C. or higher.   100 parts by weight of the (meth) acrylic monomer mixture, 2 to 40 parts by weight of the saturated polyolefin and / or a block copolymer containing a saturated polyolefin block and an aromatic vinyl monomer block, and a photopolymerization initiator The damping material composition according to claim 1 obtained by irradiation.   2 or more of the (meth) acrylic monomer having an alkyl group having 14 to 22 carbon atoms is a (meth) acrylic monomer having a branched alkyl group having 14 to 22 carbon atoms. 2. A vibration damping composition according to 2. In the dynamic viscoelasticity measurement of the shear mode in the frequency range of 0.1 to 10.0 Hz, the ratio of the shear storage modulus G′0 at 0 ° C. to the shear storage modulus G′40 at 40 ° C. (G′0 / G′40) is 15.0 or less, the shear storage modulus G ′ at 0 ° C. to 40 ° C. is 1.5 × 10 ⁴ Pascal or more and 5.0 × 10 ⁶ Pascal or less, and 0 ° C. to The damping material composition according to any one of claims 1 to 3, wherein a loss tangent tan δ at 40 ° C is 0.5 or more.   According to JIS K6868-2, the damping material composition of 20 mm × 20 mm × 1.2 mm size is bonded to a SUS304 stainless steel plate of 25 mm × 100 mm × 1.5 mm size, measuring temperature 20 ° C., pulling speed 300 mm / The damping material composition according to any one of claims 1 to 4, wherein a shear strain at break as measured by min is 600% or more.   A vibration damping structure in which a rigid sheet is sandwiched between the vibration damping composition according to any one of claims 1 to 5.

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