JP4124714B2 - Thickener for water-based damping material - Google Patents

Description

  The present invention relates to a thickener contained in a paint for forming a vibration damping material. More specifically, the present invention relates to a thickener that can improve the drying property of a coating film and suppress the occurrence of cracks and expansion on the surface of the coating film. It relates to the adhesive.

  The paint is required to have various characteristics depending on applications such as protection, insulation, and cosmetics. One of the uses of the paint is a vibration damping material. The damping material refers to a material disposed on the surface of the material in order to block transmission of sound or prevent vibration. For example, it is desirable to arrange a vibration damping material on the chassis surface of an automobile in order to keep the interior of the vehicle quiet.

  An example of a material that can be used as a vibration damping material is a sound insulation sheet. However, it takes time to arrange the sound insulation sheet. In particular, when it is arranged on a member having a complicated surface shape such as an automobile chassis, a significant reduction in productivity is inevitable. Moreover, automation is difficult and becomes an obstacle to production cost reduction.

  Therefore, attention has been focused on coating films having characteristics as vibration damping materials. Examples of the technology relating to the coating film acting as a vibration damping material include, for example, a conjugated diene monomer (a), an ethylenically unsaturated monomer (b) having an epoxy group, and an ethylenically unsaturated carboxylic acid amide monomer. There is a copolymer latex for a damping material obtained by emulsion polymerization of a monomer mixture containing an ethylenically unsaturated monomer (d) other than (c), (b) and (c) in a specific weight ratio. (See Patent Document 1). The vibration damping material is formed using a paint in which the latex is blended. If the vibration damping material is formed using the paint as described above, the productivity is good and automation is possible.

In order to act as a vibration damping material, the coating film needs to have a certain film thickness. However, when a thick coating film is dried, since there is a tendency to dry from the surface, the coating film in the vicinity of the surface is cured while the inner coating film still retains moisture. For this reason, the problem that the coating film of the surface vicinity which has already hardened expand | swells to the outer side of a coating film, or the crack generate | occur | produces a coating film by the evaporation of the water inside a coating film arises. When the coating film expands or cracks occur, the characteristics as a vibration damping material are greatly deteriorated. In this case, in order to use it as a damping material, the significance of forming the coating film is lost. These problems are particularly remarkable when a coating film is formed using an emulsion paint. This is because emulsion paints tend to immediately fuse and form a film when the amount of water around the particles decreases.
JP 2000-178499 A

  Accordingly, an object of the present invention is to provide means for improving the drying property of a coating film formed as a vibration damping material and suppressing cracks and expansion on the coating film surface.

  The present invention is a thickener for an aqueous vibration damping material comprising a polymer having an alkali-soluble monomer unit and an associative monomer unit.

  The paint in which the thickener for water-based vibration damping material of the present invention is blended can incorporate moisture into the network structure formed by the thickener. For this reason, the water retention of a coating material improves. When it has high water retention, the coating film is uniformly dried while containing a certain amount of moisture. As a result, even when a thick coating film is formed, cracks and expansion are unlikely to occur in the coating film. That is, since the paint in which the thickener for water-based vibration damping material of the present invention is blended is excellent in drying properties, cracks and expansion are hardly generated on the surface. Since there are few cracks and expansion on the surface, a high-quality vibration damping material with excellent vibration damping properties is provided.

  Further, when the alkali-soluble monomer unit is dissolved in an alkaline solution, the viscosity of the solution is increased by repulsion between the negatively charged functional groups. The thickening effect by such a mechanism is very high. For this reason, a sufficient effect can be obtained even with a small amount, and material costs and equipment costs can be reduced.

  Furthermore, the thickener for aqueous damping materials of the present invention has an associative monomer unit. A more effective thickening action is caused by the association of the hydrophobic groups contained in the associative monomer unit. Since the association between such hydrophobic groups is a relatively weak bond, the coating material containing the thickener for aqueous vibration damping material of the present invention has a thixotropic viscosity. Such properties are very useful when spraying paints. When spraying, the shearing force is strong, so the viscosity is low and it is easy to apply. On the other hand, since the shearing force is weak after application, the viscosity is high and the liquid is not easily dripped.

  The present invention is a thickener for an aqueous vibration damping material comprising a polymer having an alkali-soluble monomer unit and an associative monomer unit. Hereinafter, the thickener for damping material of the present invention will be described in detail. In the present application, the “thickener for damping material” means “thickener for aqueous damping material” unless otherwise specified.

The alkali-soluble monomer unit refers to a monomer unit in which the monomer unit has an acidic functional group or a salt thereof and performs a thickening action in an alkaline solution. Examples of the acidic functional group include a carboxyl group (—COOH), a sulfonic acid group (—SO ₃ H), and a phosphoric acid group (—PO ₃ H ₂ ). Salts can be formed by neutralizing acidic functional groups with alkaline compounds and the like. Examples of the salt include sodium salt, potassium salt or ammonium salt of an acidic functional group. However, acidic functional groups and salts thereof are not limited to these. Of the acidic functional groups and salts thereof, carboxyl groups and salts thereof are preferred. This is because a monomer having a carboxyl group or a salt thereof is less hydrophilic than other acid group-containing monomers and has high stability during polymerization. Among the monomers having a carboxyl group or a salt thereof, acrylic acid and methacrylic acid having good copolymerizability with other monomers and salts thereof are preferable.

  In addition, an alkali-soluble monomer unit consists only of a monomer unit having an acidic functional group, and there may be no monomer unit having a salt thereof. On the contrary, the alkali-soluble monomer unit is composed only of a monomer unit having a salt thereof, and there may be no monomer unit having an acidic functional group. The alkali-soluble monomer unit may include both a monomer unit having an acidic functional group and a monomer unit having a salt thereof.

  The alkali-soluble monomer unit is formed by polymerization using a polymerizable monomer having these functional groups. The salt can be formed by neutralizing the acid contained in the alkali-soluble monomer unit after forming the polymer. You may form a polymer using the monomer neutralized previously.

The thickening action caused by the alkali-soluble monomer unit will be briefly described. When the alkali-soluble monomer unit is present in the alkaline solution, the acidic functional group of the alkali-soluble monomer unit is present in an ionized state. For example, a carboxyl group (—COOH) exists as an anion (—COO ⁻ ) by a base such as NaOH. -COO ^- because it has negatively charged polymer having an alkali-soluble monomer unit and extends in the solution by electrical repulsion. As a result, the viscosity of the solution increases.

  Monomers having a carboxyl group, such as acrylic acid, methacrylic acid, acryloxypropionic acid, citraconic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride, etc., are used as monomers for forming the alkali-soluble monomer unit: vinyl sulfone Monomers having a sulfonic acid group such as acid, styrene sulfonic acid, sulfoethyl (meth) acrylate: mono (2-methacryloyloxyethyl) phosphate, mono (2-acryloyloxyethyl) phosphate, 2- (meth) acryloyloxypropyl phosphate, Monomers having a phosphoric acid group such as 2- (meth) acryloyloxy-3-chloropropyl phosphate and 2- (meth) acryloyloxyethyl phenyl phosphate are included. Also included are sodium, potassium or ammonium salts of these monomers. However, the monomer as a raw material of the alkali-soluble monomer unit is not limited to these, and may be polymerizable and have an acidic functional group or a salt thereof. Moreover, the monomer as a raw material used may be 1 type, or 2 or more types.

  The associative monomer unit is a monomer unit that has a hydrophobic group in a side chain and allows a plurality of polymers to associate with each other through the hydrophobic group. Hydrophobic groups that allow the polymer to associate include the following formula (I):

The group represented by these is mentioned.

In the formula (I), R ¹ represents a methylene group (—CH ₂ —), an ethylene group (—CH ₂ CH ₂ —), a propylene group (—CH ₂ CH (CH ₃ ) —) or a butylene group (—CH ₂ CH _(CH 2 _CH 3) -) it is. Among these, an ethylene group is preferred for reasons such as availability. When it is an ethylene group, the repeating unit represented by (R ¹ —O) is ethylene oxide. R ¹ may be composed of a plurality of functional groups. For example, the above (R ¹ —O) _n may be a combination of ethylene oxide and propylene oxide.

n is the number of repetitions of the repeating unit represented by ^(R 1 -O). n is preferably 10 to 300, more preferably 10 to 100, still more preferably 20 to 80, particularly preferably 40 to 60, and most preferably 45 to 55. .

  X is a direct bond, —C (═O) —, or —C (═O) NH—.

R ² is a hydrocarbon group having 6 to 30 carbon atoms. Hydrocarbon groups include linear, branched or cyclic alkyl groups, aryl groups, alkylaryl groups, and the like. These hydrocarbon groups may be partially substituted as long as the association action by the associative monomer unit is not inhibited. The straight chain alkyl group includes a hexyl group, a heptyl group, an octyl group, a nonyl group, a dodecyl group, an octadecyl group, and the like. The branched alkyl group includes a 3-methylhexyl group, a 4,4-diethyloctyl group, and the like. The cyclic alkyl group includes a cyclooctyl group, a cholestanyl group, a lanostannyl group and the like. The aryl group includes a phenyl group, a naphthyl group, an anthryl group and the like. The alkylaryl group includes a nonylphenyl group, a dodecylphenyl group, a nonylphenyl group, and the like. In view of efficient association, R ² is preferably a hydrocarbon group having 8 to 30 carbon atoms, more preferably an alkyl group having 8 to 30 carbon atoms, and further preferably an alkyl group having 12 to 20 carbon atoms. Group, particularly preferably an alkyl group having 16 to 20 carbon atoms, and most preferably an alkyl group having 18 carbon atoms.

The thickening action caused by the associative monomer unit will be briefly described. In the associative monomer unit, the moiety that actually associates is the R ² moiety in formula (I). Since R ² is a hydrophobic functional group such as a dodecyl group, the polymer dispersed in the solution associates using the hydrophobicity of R ² . Since the association between the hydrophobic groups is a relatively weak bond, a thixotropic viscosity can be exhibited by the thickener for a vibration damping material of the present invention.

Repeating unit represented by (R 1 ^-O) is to increase the freedom of movement of R ^2, it is a part for facilitating meetings. That is, when R ² is directly bonded to the main chain or close to the main chain, it cannot move freely even if R ² has hydrophobicity. For this reason, R ² cannot meet well. On the other hand, when R ² is separated from the main chain portion by (R ¹ —O) by a considerable distance, R ² can associate with each other well.

  A preferred specific embodiment of the associative monomer unit is represented by the following formula (II):

It is. Monomer units represented by the formula (II) has a functional group of the formula (I) R ¹ is ethylene group in the side chain. In the formula (II), n, X, and R ² are as defined above, and thus description thereof is omitted.

  The polymer used as a thickener for damping material may further have other monomer units. For example, an alkali-soluble monomer unit, an associative monomer unit, and a monomer unit derived from a copolymerizable ethylenically unsaturated monomer (hereinafter referred to as “ethylenically unsaturated monomer unit”). May be included). When the polymer has an ethylenically unsaturated monomer unit, the polymerization stability is good.

  Examples of ethylenically unsaturated monomers include styrene-based polymerizable monomers such as styrene, vinyl toluene, α-methyl styrene, ethyl vinyl benzene, and chloromethyl styrene; (meth) acrylamide, N-monomethyl (meth) acrylamide, N-monoethyl ( (Meth) acrylamide, N, N-dimethyl (meth) acrylamide and other (meth) acrylamide polymerizable monomers; (meth) acrylic such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate (Meth) acrylic acid ester-based polymerizable monomer that is an ester of an acid and an alcohol having 1 to 8 carbon atoms; a cyclohexyl group-containing polymerizable monomer such as cyclohexyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate; (Meth) acrylic acid 2-hydroxypropiate Hydroxyl group-containing (meth) acrylic acid ester-based polymerizable monomer such as polyethylene glycol (meth) acrylic ester and other (meth) acrylic acid and polyalkylene glycol monoesters of polyethylene glycol chain-containing polymerizable monomers; vinyl acetate N-vinyl pyrrolidone, dimethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, vinyl pyridine, vinyl imidazole, and other basic polymerizable monomers; N -Crosslinkable (meth) acrylamide polymerizable monomers such as methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide; vinyltrimethoxysilane, vinyltriethoxysilane, γ- (meta Hydrolyzable silicon group-containing polymerizable monomer having a functional group directly bonded to a silicon atom such as acryloylpropyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, and allyltriethoxysilane; glycidyl (meth) acrylate, acrylglycidyl ether Epoxy group-containing polymerizable monomers such as 2-isopropenyl-2-oxazoline, 2-vinyloxazoline and other oxazoline group-containing polymerizable monomers; (meth) acrylic acid-2-aziridinylethyl, (meth) acryloylaziridine Aziridine group-containing polymerizable monomers such as vinyl fluoride, vinylidene fluoride, vinyl chloride, vinylidene chloride and the like. Two or more types of ethylenically unsaturated monomers may be used. Other monomers may be used as a raw material.

  The polymer used as a thickener for vibration damping materials may have a crosslinkable monomer unit. The crosslinkable monomer unit can be formed from a polyfunctional monomer having two or more polymerizable unsaturated groups in the molecule. Such polyfunctional monomers include (meth) acrylic acid, ethylene glycol, 1,3-butylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, polyethylene glycol, propylene glycol, polypropylene glycol, trimethylol. (Meth) acrylic acid ester monomers such as esterified products with polyhydric alcohols such as propane, pentaerythritol and dipentaerythritol; (meth) acrylic acid amide monomers such as methylene (meth) acrylamide; diallyl phthalate, diallylmer Allyl polymerizable monomers such as rate and diallyl fumarate; allyl (meth) acrylate and divinylbenzene are included. Two or more of these may be used in combination. However, the crosslinkable monomer unit is not limited to these as long as it crosslinks between polymer chains.

The polymer used as the thickener for the vibration damping material is a combination of the above monomer units. For reference, for example, a monomer unit derived from methacrylic acid; a monomer unit represented by the above formula (II) in which n is 50, X is —C (═O) —, and R ² is —C ₁₇ H ₃₅ ; And a polymer comprising monomer units derived from ethyl acrylate has the following formula:

It is represented by

  The thickener for vibration damping material of the present invention comprises a polymer having an alkali-soluble monomer unit and an associative monomer unit. Therefore, the “thickener for vibration damping material” includes not only a polymer alone but also a solution such as an emulsion containing the polymer in its concept. Moreover, the thickener for vibration damping materials of the present invention is usually used in an aqueous system.

  Next, the constitution ratio of each monomer unit of the polymer used as the thickener for vibration damping material of the present invention will be described. The polymer used as a thickener essentially contains an alkali-soluble monomer unit and an associative monomer unit. Moreover, the polymer may contain other monomer units, such as a monomer unit resulting from an ethylenically unsaturated monomer.

  The blending ratio of the alkali-soluble monomer unit is preferably 20 to 69 mol%, more preferably 25 to 64 mol%, based on all monomer units. If the blending ratio of the alkali-soluble monomer unit is too low, it is difficult to obtain alkali-solubility, so that sufficient thickening may not be obtained. On the other hand, if the blending ratio of the alkali-soluble monomer unit is too high, the polymerization stability in emulsion polymerization may not be maintained. In addition, when using 2 or more types of alkali-soluble monomer units, it is preferable that the total amount of each alkali-soluble monomer unit satisfy | fills the said range.

  The blending ratio of the associative monomer unit is preferably 0.001 to 2.0 mol%, more preferably 0.005 to 1.5 mol%, based on all monomer units. If the blending ratio of the associative monomer unit is too low, the amount of the hydrophobic group in the polymer is insufficient, and the viscosity modification by the associative monomer unit may be insufficient. On the other hand, if the blending ratio of the associative monomer unit is too high, it is difficult to produce a copolymer by emulsion polymerization, and the association between hydrophobic groups in the same polymer increases, which has the effect of increasing viscosity. descend.

  The blending ratio of the ethylenically unsaturated monomer is preferably 30 to 79 mol%, more preferably 35 to 74 mol%, based on all monomer units. If the blending ratio of the ethylenically unsaturated monomer unit is too low, the polymerization stability in emulsion polymerization may not be maintained. On the other hand, if the blending ratio of the ethylenically unsaturated monomer unit is too high, it is difficult to dissolve in alkali, and thus sufficient viscosity may not be obtained.

  The weight average molecular weight of the polymer used as the thickener in the thickener for vibration damping material of the present invention is preferably 3,000 or more, more preferably 10,000 or more, and still more preferably 100,000 or more. However, when a crosslinkable monomer is used, the molecular weight becomes very high, and it is difficult to measure the molecular weight by GPC.

  A polymer as a thickener is obtained by polymerizing monomer components. The polymerization method of the monomer component is not particularly limited. Polymerization can be performed using emulsion polymerization, reverse phase suspension polymerization, suspension polymerization, solution polymerization, aqueous solution polymerization, bulk polymerization, and the like. Among these polymerization methods, emulsion polymerization is preferable. In emulsion polymerization, a high molecular weight copolymer can be polymerized at a high concentration, the handling viscosity is low, and the production cost is low. Even when the polymer is produced by emulsion polymerization, the procedure is not particularly limited. For example, an aqueous solution in which a predetermined amount of monomer is dissolved may be prepared, a pre-emulsion may be formed using an emulsifier, and then a polymerization initiator may be added to advance the polymerization reaction. The blending ratio of each monomer is determined according to the blending ratio of the monomer units in the polymer described above.

  As the alkali-soluble monomer unit, ethylenically unsaturated monomer, etc., commercially available drugs may be used, or raw materials may be prepared by themselves. As the associative monomer unit, a commercially available drug may be used, or it may be synthesized according to a known method described in JP-A No. 2001-240630.

  Hereinafter, the emulsifier, the polymerization initiator, and the polymerization conditions used when obtaining a polymer as a thickener by emulsion polymerization will be described.

  Emulsion polymerization can be performed in an aqueous medium. The aqueous medium is not particularly limited, and examples thereof include water, a mixed solvent of one or more kinds of solvents that can be mixed with water, a mixed solvent in which water is a main component in such a solvent, and the like. Can be mentioned. Of these, water is preferred.

  The emulsifier is not particularly limited, and various emulsifiers can be used. For example, anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, polymer surfactants, reactive surfactants thereof and the like can be used as emulsifiers. These may be used in combination.

  Examples of anionic surfactants include alkyl sulfate salts such as sodium dodecyl sulfate, potassium dodecyl sulfate, and ammonium alkyl sulfate; sodium dodecyl polyglycol ether sulfate; sodium sulforicinoate; alkyl sulfonate such as sulfonated paraffin salt; sodium dodecylbenzene Alkyl sulfonates such as sulfonates and alkali metal sulfates of alkali phenol hydroxyethylene; high alkyl naphthalene sulfonates; naphthalene sulfonic acid formalin condensates; fatty acid salts such as sodium laurate, triethanolamine oleate, triethanolamine abiates Oxyalkyl ether sulfate ester salt; Polyoxyethylene carboxylate sulfate ester Le salts; polyoxyethylene phenyl ether sulfate; dialkyl succinate sulfonate; and the like polyoxyethylene alkyl aryl sulfate salts. However, the anionic surfactant is not limited to these. Two or more anionic surfactants may be used.

  Nonionic surfactants include polyoxyethylene alkyl ethers; polyoxyethylene alkyl aryl ethers; sorbitan aliphatic esters; polyoxyethylene sorbitan aliphatic esters; aliphatic monoglycerides such as monolaurate of glycerol; polyoxyethyleneoxypropylene Copolymer; Condensation products of ethylene oxide and aliphatic amines, amides or acids are included. However, the nonionic surfactant is not limited to these. Two or more nonionic surfactants may be used.

  Cationic surfactants include dialkyldimethylammonium salts, ester-type dialkylammonium salts, amide-type dialkylammonium salts, dialkylimidazolinium salts, and the like. However, the cationic surfactant is not limited to these. Two or more cationic surfactants may be used.

  Amphoteric surfactants include alkyldimethylaminoacetic acid betaines, alkyldimethylamine oxides, alkylcarboxymethylhydroxyethyl imidazolinium betaines, alkylamidopropyl betaines, alkylhydroxysulfobetaines, and the like. However, the amphoteric surfactant is not limited to these. Two or more amphoteric surfactants may be used.

  Polymeric surfactants include polyvinyl alcohol and modified products thereof; (meth) acrylic acid-based water-soluble polymers; hydroxyethyl (meth) acrylic acid-based water-soluble polymers; hydroxypropyl (meth) acrylic acid-based water-soluble polymers Molecule; polyvinylpyrrolidone and the like are included. However, the polymer surfactant is not limited to these. Two or more kinds of polymer surfactants may be used.

  Among the emulsifiers, it is preferable to use a reactive emulsifier. From the environmental viewpoint, it is preferable to use a non-nonylphenyl emulsifier.

  The polymerization initiator is not particularly limited as long as it is a substance that decomposes by heat and generates radical molecules. In emulsion polymerization, a water-soluble initiator is preferably used. Examples of the polymerization initiator include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate; 2,2′-azobis (2-amidinopropane) dihydrochloride, 4,4′-azobis (4-cyanopentanoic acid) Water-soluble azo compounds such as hydrogen peroxide; thermal decomposition initiators such as hydrogen peroxide; hydrogen peroxide and ascorbic acid, t-butyl hydroperoxide and rongalite, potassium persulfate and metal salts, ammonium persulfate and sodium bisulfite, etc. Redox polymerization initiators and the like are included. However, the polymerization initiator is not limited to these. Two or more polymerization initiators may be used.

  The usage-amount of a polymerization initiator is not specifically limited, What is necessary is just to set suitably according to the kind etc. of polymerization initiator. For example, when the total amount of all monomers is 100 parts by mass, it is preferably 0.1 to 2 parts by mass, more preferably 0.2 to 1 part by mass.

  Emulsion polymerization for producing a thickener for damping material is 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. Examples of the method for adding a monomer, a polymerization initiator, and the like include a batch addition method, a continuous addition method, a multistage addition method, and the like. You may combine these addition methods suitably.

  The polymerization temperature in emulsion polymerization is not particularly limited. The polymerization temperature is preferably 0 to 100 ° C, more preferably 40 to 95 ° C. The polymerization time is not particularly limited. The polymerization time is preferably 3 to 15 hours. When emulsion polymerization is performed, a hydrophilic solvent, an additive, or the like may be added as long as the physical properties of the obtained polymer are not adversely affected. The method for adding the monomer component to the emulsion polymerization reaction system is not particularly limited, and a batch addition method, a monomer component dropping method, a pre-emulsion method, a power feed method, a seed method, a multistage addition method, or the like may be used. it can.

  The nonvolatile content in the emulsion obtained after the emulsion polymerization reaction, that is, the polymer as a thickener is preferably 60% by mass or less. If the non-volatile content exceeds 60% by mass, the viscosity of the emulsion is too high, so that the dispersion stability cannot be maintained and aggregation may occur. Although there is no limitation in particular about the average particle diameter of the said emulsion, Preferably it is 10 nm-1 micrometer, More preferably, it is 20-500 nm. If the average particle size of the emulsion is less than 10 nm, the viscosity of the emulsion becomes too high, and the dispersion stability may not be maintained and aggregation may occur. On the other hand, when it exceeds 1 μm, it is no longer an emulsion.

  In emulsion polymerization, a chain transfer agent may be used in an amount of 0.001 to 2 parts by mass per 100 parts by mass of the monomer component in order to reduce the molecular weight. Chain transfer agents include halogen-substituted alkanes such as carbon tetrachloride, bromoform, bromotrichloroethane; alkyl mercaptans such as n-dodecyl mercaptan, tert-dodecyl mercaptan, octyl mercaptan, tetradecyl mercaptan, hexadecyl mercaptan; butyl thioglycolate, Examples include thioesters such as alkyl monothioglycolate such as isooctyl thioglycolate and dodecyl thioglycolate; alcohols such as methanol, ethanol and isopropanol; α-methylstyrene dimer, terpinol, terpinene and dipentene. However, the chain transfer agent is not limited to these. Two or more chain transfer agents may be used.

  As shown in the Examples, the thickener for damping material of the present invention is blended with other components to form a damping material composition, for example, an emulsion paint for damping material. Other ingredients to be blended are: solvent; aqueous copolymer latex; plasticizer; stabilizer; wetting agent; preservative; antifoaming agent; inorganic filler; coloring agent; An antiaging agent; an antifungal agent; an ultraviolet absorber; an antistatic agent and the like are included. Preferably, the composition for damping material includes at least the thickener for aqueous damping material of the present invention, an aqueous copolymer latex, and an inorganic filler.

  These blends can be appropriately selected from known materials. For example, examples of the solvent include ethylene glycol, butyl cellosolve, butyl carbitol, and butyl carbitol acetate. Examples of the aqueous copolymer latex include styrene / butadiene copolymer latex, (meth) acrylic acid copolymer emulsion, styrene / (meth) acrylic acid copolymer emulsion, vinyl acetate copolymer emulsion, and the like. Can be mentioned. Two or more of these may be blended. Moreover, 2 or more types may be compounded by multistage polymerization. Inorganic fillers include calcium carbonate, kaolin, silica, talc, barium sulfate, alumina, iron oxide, titanium oxide, glass talk, magnesium carbonate, aluminum hydroxide, talc, diatomaceous earth, clay, etc .; glass flakes And flaky inorganic fillers such as mica; fibrous inorganic fillers such as metal oxide whiskers and glass fibers. Examples of the colorant include organic or inorganic colorants such as titanium oxide, carbon black, dial, hansa yellow, benzine yellow, phthalocyanine blue, and quinacridone red. 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 rust preventive pigment include a metal phosphate, a metal molybdate, and a metal borate. Examples of the antifoaming agent include silicon-based antifoaming agents.

  The composition for damping material preferably contains a solid content in the range of about 40 to 90% by mass, more preferably about 50 to 85% by mass, and still more preferably about 60 to 80% by mass. Moreover, the pH of the composition for vibration damping materials is preferably within the range of 7 to 11, more preferably 8 to 10.

  The compounding quantity of each component in the composition for vibration damping materials is not particularly limited. Usually used amounts are formulated taking into account the properties obtained. For example, the blending amount of the thickener for damping material of the present invention is a solid content, preferably 0.01 to 2 parts by mass, more preferably 100 parts by mass of the solid content of the composition for damping material. 0.05 to 1.5 parts by mass, more preferably 0.1 to 1 part by mass. The blending amount of the aqueous copolymer latex is preferably 10 to 60 parts by weight, more preferably 15 to 55 parts by weight, and still more preferably 100 parts by weight of the solid content of the composition for damping material. 20 to 50 parts by mass. The blending amount of the inorganic filler is preferably 40 to 90 parts by mass, more preferably 45 to 85 parts by mass, and further preferably 50 to 80 parts by mass with respect to 100 parts by mass of the solid content of the vibration damping composition. is there. However, the blending amount is not limited to this range.

  It is preferable that the composition for vibration damping materials also contains a polyvalent metal compound. Thereby, stability of the composition for damping materials, dispersibility, heat drying property, and damping properties of the damping material formed from the damping material composition are improved. The polyvalent metal compound is not particularly limited, and examples thereof include zinc oxide, zinc chloride, and zinc sulfate. Two or more of these may be used in combination.

  The form of the polyvalent metal compound is not particularly limited, and may be, for example, a powder, an aqueous dispersion, an emulsion dispersion, or the like. In these, since the dispersibility in the composition for damping materials improves, it uses preferably in the form of an aqueous dispersion or an emulsified dispersion, More preferably, an emulsified dispersion. Moreover, the usage-amount of a polyvalent metal compound becomes like this. Preferably it is 0.05-5.0 mass parts with respect to 100 mass parts of solid content in the composition for damping materials, More preferably, it is 0.05-3. .5 parts by mass.

  The apparatus used for mixing is not specifically limited, For example, a butterfly mixer, a planetary mixer, a spiral mixer, a kneader, a dissolver etc. are used.

  The aqueous copolymer latex is not particularly limited, and can be produced with reference to the method for producing an aqueous copolymer latex described in JP-A No. 2000-355602. For example, an acid component that is a hydrophilic component may be charged in the flask in advance to initiate polymerization. Of course, a water-based copolymer latex may be produced using a novel production method. The aqueous copolymer latex is blended with a thickener that is excellent in various properties such as water retention and thickening. For this reason, even if it is a case where the coating film with a thick film thickness is formed, the vibration damping material which is hard to generate | occur | produce a crack and expansion | swelling and is excellent in vibration damping property is provided. Aqueous copolymer latex tends to immediately melt and form a film when the amount of water around the particles decreases, so when forming a coating film using an aqueous copolymer latex, the present invention It is particularly useful. In addition, the thickener for damping materials of this invention may be previously mix | blended with the composition for damping materials.

  When the vibration damping composition is applied to the substrate and dried, a coating film that acts as a vibration damping material is formed. The substrate is not particularly limited. In addition, a brush, a spatula, an air spray, an airless spray, a mortar gun, a ricin gun, or the like can be used to apply the vibration damping composition to the substrate.

  The composition for damping material prepared using the thickener for damping material of the present invention is applied to the interior floor of automobiles, railway vehicles, ships, aircraft, electrical equipment, building structures, construction equipment, etc. . However, it is not limited to these.

  The coating film formed using the vibration damping composition of the present invention is excellent in vibration damping properties. The loss factor (tan δ) when the coating film is formed is preferably 0.15 or more, more preferably 0.16 or more, and further preferably 0.18 or more. In addition, it means that it is excellent in damping property, so that the said loss coefficient is large. The loss factor can be calculated by the method described in the examples.

  The application amount of the damping material paint is set according to the application, desired performance, and the like. Specifically, the thickness of the coating film when dried is preferably 0.5 to 5.0 mm, more preferably 1.5 to 4.5 mm.

  In order to form a film by applying the vibration damping coating material, the film may be dried by heating or may be dried at room temperature. Heat drying is preferable from the viewpoint of efficiency. Even if the damping material coating formed using the damping material composition of the present invention is forcibly heated and dried, the coating material is excellent in drying properties, so that expansion and cracking are unlikely to occur. For this reason, it is particularly beneficial when heat drying is used. The temperature for heat drying is preferably 80 to 210 ° C, more preferably 110 to 160 ° C.

  The effects of the present invention will be described using examples and comparative examples. Unless otherwise specified, “part” means “part by mass” in the following examples.

[Example 1: Synthesis of polymer having alkali-soluble monomer unit and associative monomer unit]
In a four-necked separable flask equipped with a stirrer, thermometer, condenser, nitrogen inlet tube, and dropping funnel, ion-exchanged water (115 parts), polyoxyethylene dodecyl ether sulfonate ammonium salt (1.5 parts) Was introduced. While stirring at an internal temperature of 68 ° C., nitrogen was gently flowed to completely replace the inside of the reaction vessel with nitrogen. Next, ammonium sulfonate (1.5 parts) of polyoxyethylene dodecyl ether was dissolved in ion-exchanged water (92 parts).

  Here, methacrylic acid (40 parts), octadecyl polyoxyethylene (3-methyl-3-butenyl) ether ester bond (ethylene oxide 50 mol adduct) (10 parts), and ethyl acrylate as a polymer monomer (50 parts) of the mixture was added and stirred to prepare a pre-emulsion. Incidentally, methacrylic acid is a raw material for alkali-soluble monomer units, octadecyl polyoxyethylene (3-methyl-3-butenyl) ether is a raw material for associative monomer units, and ethyl acrylate is a raw material for ethylenically unsaturated monomer units. It is. In addition, the structure of the ester bond (ethylene oxide 50 mol addition product) of octadecyl polyoxyethylene (3-methyl-3-butenyl) ether is shown below.

  5% of the pre-emulsion containing the polymer monomer was put into a reaction vessel and stirred for 5 minutes, and then sodium bisulfite (0.017 part) was added. Separately, ammonium persulfate (0.23 parts) was mixed with ion-exchanged water (23 parts) to prepare a polymerization initiator aqueous solution. 5% of this polymerization initiator aqueous solution was put into the reaction vessel and stirred for 20 minutes to carry out initial polymerization. The internal temperature of the reaction vessel was maintained at 72 ° C., and the remaining pre-emulsion and initiator aqueous solution were uniformly added dropwise over 2 hours. After completion of dropping, the dropping tank was washed with ion-exchanged water (8 parts) and then charged into the reaction vessel. The internal temperature was kept at 72 ° C., and stirring was continued for another hour, followed by cooling to complete the reaction. A thickener 1 for damping material having a nonvolatile content of 30% was obtained.

[Example 2: Synthesis of polymer having alkali-soluble monomer unit and associative monomer unit]
As monomers of the polymer, methacrylic acid (40 parts), ester bond of octadecyl polyoxyethylene (3-methyl-3-butenyl) ether (ethylene oxide 50 mol adduct) (10 parts), and ethyl acrylate (50 parts) ), Except that methacrylic acid (40 parts), octadecyl polyoxyethylene acrylate ester bond (ethylene oxide 50 mol adduct) (10 parts), and ethyl acrylate (50 parts) were used. A thickener 2 for damping material was obtained by the same method.

[Comparative Example 1: Synthesis of thickener having no associative monomer unit]
As monomers of the polymer, methacrylic acid (40 parts), ester bond of octadecyl polyoxyethylene (3-methyl-3-butenyl) ether (ethylene oxide 50 mol adduct) (10 parts), and ethyl acrylate (50 parts) ) Was used in the same manner as in Example 1 except that methacrylic acid (35 parts) and ethyl acrylate (65 parts) were used.

[Examples 3 and 4, Comparative Example 2: Preparation of emulsion paint for vibration damping material]
A thickening agent for vibration damping materials obtained in Examples 1 and 2 and Comparative Example 1, and other components are blended at the blending ratio shown below, and an emulsion paint for vibration damping materials which is a composition for vibration damping materials Was prepared.

(Mixing ratio)
・ Emulsion (Nippon Shokubai Co., Ltd. Acreset DC-172) 148 parts ・ Calcium carbonate (Nitto Flour & Chemical Co., Ltd. NN # 200) 240 parts ・ Additive (propylene glycol) 19 parts ・ Dispersant (Kao Corporation) (Demol EP) 4.3 parts ・ Thickener for damping material 7 parts ・ Defoaming agent (Nopco 8034L manufactured by San Nopco Co., Ltd.) 0.3 part In Comparative Example 2, the thickener for damping material is 14 Partly formulated. This is because the viscosity of the emulsion paint for damping material is set to a predetermined value.

  The drying property of the prepared emulsion paint for damping material and the loss factor of the formed coating film were evaluated. The measuring method of each evaluation item is as follows. The evaluation results are summarized in Table 1.

[Drying]
On the steel plate (SPCC-SD manufactured by Nippon Test Panel; 75 mm width x 150 mm length x 0.8 mm thickness), the emulsion for damping material is 1.5 mm, 3.0 mm, and 4.5 mm. As applied. Thereafter, the applied emulsion for vibration damping material was dried at 150 ° C. for 30 minutes using a hot air dryer. The resulting dried coating film was evaluated for expansion and cracks. The case where there was no expansion and cracks was marked with ◎, the case where there was almost no expansion and cracks was marked with ○, the case where there was little expansion and cracking was marked with Δ, and the case where many expansions and cracks occurred were marked with ×.

[Loss factor]
On the steel plate (SPCC-SD manufactured by Nippon Test Panel; 15 mm width × 250 mm length × 0.8 mm thickness), the emulsion for vibration damping material was applied so that the coating thickness was 3.0 mm. Thereafter, the applied emulsion for vibration damping material was dried at 150 ° C. for 30 minutes using a hot air dryer. The damping property of the obtained dried coating film was evaluated using a loss factor. The loss factor was evaluated by measuring tan δ of the cantilever method in a measurement environment of 25 ° C. using an Ono Sokki Co., Ltd. loss factor measurement system. The larger the loss factor value, the better the damping performance.

  As shown in Table 1, the coating film formed using the emulsion for vibration damping materials of the present invention is less susceptible to cracking and expansion and exhibits excellent vibration damping properties.

  Since the paint blended with the thickener for vibration damping material of the present invention has improved water retention, even if a thick coating film is formed, the coating film is hardly cracked or expanded. For this reason, the coating film which is excellent in vibration damping property is formed. Moreover, the viscosity of a solution rises effectively by the alkali-soluble monomer unit which the thickener for damping materials of this invention has. Furthermore, a more effective thickening action is caused by the associative monomer unit of the thickener for vibration damping material of the present invention.

Claims (5)

Made of a polymer having an alkali-soluble monomer unit and an associating monomer unit, before Symbol associating monomer unit in the side chain, the following formula (I):
(In the formula, R ¹ is one or more selected from the group consisting of a methylene group, an ethylene group, a propylene group, and a butylene group, n is 10 to 300, X is a direct bond, —C (═O )-, Or -C (= O) NH-, and R ² is a hydrocarbon group having 6 to 30 carbon atoms)
A thickener for aqueous vibration damping materials , characterized by having a group represented by the formula: The associative monomer unit has the following formula (II):
(Wherein, n, X and ^{R 2} are defined as)
In water for vibration damping materials thickener according to claim 1, characterized by being represented. The polymer according to claim 1 or 2, characterized by further comprising the alkali-soluble monomer unit and the associating monomer unit monomer copolymerizable with a raw material, the monomer units resulting from the ethylenically unsaturated monomer A thickener for aqueous vibration damping materials as described in 1. The blending ratio of the alkali-soluble monomer unit is 20 to 69 mol% with respect to all the monomer units, and the blending ratio of the associative monomer unit is 0.001 to 2.0 mol% with respect to all the monomer units. The mixing ratio of the monomer unit resulting from the ethylenically unsaturated monomer is 30 to 79 mol% with respect to the total monomer units, and the thickener for an aqueous vibration damping material according to claim 3 . Claim 1-4 aqueous vibration damping material for a thickener according to any one of the aqueous copolymer latex, and an inorganic filler, the damping material composition.