Balance weight

Abstract

The purpose of the present invention is to: (1) provide a composition for balance weights which includes a moisture-curable adhesive that is solid at ordinary temperature and a balance weight obtained from the composition; and / or (2) provide a composition for balance weights and a balance weight obtained from the composition, wherein the production and application of the composition for balance weights are easy to automate, the composition has a high solidification rate and is excellent in terms of rapid curing and rapid bonding, the composition, even when a balance measurement is made immediately after application thereof, can be inhibited from suffering sagging or positional shifting to make the next step possible, and the composition has excellent workability. This composition for balance weights: comprises (A) a moisture-curable adhesive which is solid at ordinary temperature and (B) a tungsten-based powder; is solid at ordinary temperature; and has a specific gravity less than 8.5.

Description

balance weight

[0001] The present invention relates to a composition for a balance weight and a balance weight.

[0002] Generally, there are two methods for adjusting the balance of a rotating body using dynamic balancing. The first method is to remove locally heavy parts and adjust the overall balance. The second method is to apply balance weights to locally light parts and adjust the overall balance. The second method is simpler and more cost-effective than the first method. In order to correct unbalanced rotation caused by uneven moments of inertia, a widely used method is to apply balance weights to the periphery of the rotating body and correct the amount of unbalance.

[0003] As a balance weight composition, for example, a balance weight composition containing an adhesive made of an epoxy resin is used. A widely known example of such a balance weight composition is "Dream Weight," an epoxy resin composition for balance adjustment manufactured by Toa Densoku Co., Ltd. Conventionally, the balance of a rotating body is adjusted by measuring in advance the position where a weight (balance weight) is to be attached to the rotating body, attaching an epoxy resin composition for balance weight to that position, and then curing it at room temperature and / or by heating.

[0004] Patent Documents 1 to 3 disclose balance weights used to correct unbalanced rotation of a rotating body. These balance weight compositions are mainly two-component mixtures in which a base agent and a curing agent are mixed and cured by reaction. However, the time from mixing the two components (base agent and curing agent) until use (pot life) is limited, and the balance weight composition must be applied to the target object within the pot life. Furthermore, due to the high viscosity of the putty-like structure, the two components must be mixed and applied manually, making automation difficult and reducing workability. Patent Documents 4 and 5 disclose balance weight compositions containing a metal powder primarily composed of tungsten and a one-component curing adhesive with a viscosity of 1 Pa·s to 50 Pa·s at room temperature and thixotropy. These balance weight compositions are said to be easy to manage and handle, have excellent workability, and are also said to facilitate automated application.

[0005] Japanese Patent Application Laid-Open No. 2001-298929 Japanese Patent Application Laid-Open No. 2001-298925 Japanese Patent Application Laid-Open No. 3-107646 Japanese Patent Application Laid-Open No. 2004-36675 Japanese Patent Application Laid-Open No. 2005-121166

[0006] Conventional balance weight compositions have been difficult to automate during preparation, application, and placement, resulting in poor workability. Furthermore, when an adhesive that is liquid at room temperature is used, if the balance is measured immediately after application and placement, the balance weight composition may not have solidified, resulting in dripping or deviation from the application and placement position. Therefore, the composition must be solidified before proceeding to the next step, resulting in poor workability. The problems the present invention aims to solve are: (1) to provide a balance weight composition using a moisture-curing adhesive that is solid at room temperature, and a balance weight obtained therefrom; and / or (2) to provide a balance weight composition and a balance weight obtained therefrom that are easy to automate during preparation, application, and placement, have a fast solidifying rate, and are excellent in fast-curing and fast-adhesion properties, and are capable of suppressing dripping and deviation even when the balance is measured immediately after application and placement of the balance weight composition, allowing for proceeding to the next step and providing excellent workability.

[0007] The present inventors conducted extensive research to solve the above-mentioned problems, and as a result, discovered that a balance weight having a specific configuration can solve the above-mentioned problems, leading to the completion of the present invention. Specifically, the present invention is as follows: Item 1: A balance weight composition comprising: a moisture-curable adhesive (A) that is solid at room temperature; and a tungsten-based powder (B), which is solid at room temperature and has a specific gravity of 8.5 or less. Item 2: The balance weight composition according to Item 1, in which the moisture-curable adhesive (A) that is solid at room temperature is primarily composed of an isocyanate group-containing urethane prepolymer or a crosslinkable silicon group-containing polymer. Item 3: The balance weight composition according to Item 1 or 2, in which the moisture-curable adhesive (A) that is solid at room temperature has a viscosity of 50 Pa s or less at 120°C, and the tungsten-based powder (B) has a particle size in the range of 0.1 to 200 μm. Item 4: A balance weight in which the composition for balance weights according to any one of Items 1 to 3 is applied to a required portion of a rotating body to adjust the balance of the rotating body. Item 5: A method for applying the composition for balance weights according to any one of Items 1 to 3 to an applicable portion of a rotating body to adjust the balance.

[0008] The present invention provides a balance weight composition that uses a moisture-curing adhesive that is solid at room temperature, and a balance weight obtained therefrom. The present invention also provides a balance weight composition and a balance weight obtained therefrom that can be easily automated during preparation, application, and placement of the balance weight composition, have a fast solidification rate, excellent fast-curing properties, and fast adhesion, and can suppress dripping and misalignment even when the balance is measured immediately after application and placement of the balance weight composition. The composition can be easily expanded to the next step, and has excellent workability.

[0009] The balance weight composition of the present invention contains a moisture-curable adhesive (A) that is solid at room temperature and a tungsten-based powder (B), is solid at room temperature, and has a specific gravity of 8.5 or less. The balance weight of the present invention is obtained by applying the balance weight composition to a required portion of a rotating body to adjust its balance. The inventors have discovered that a balance weight containing a moisture-curable adhesive (A) that is solid at room temperature and a tungsten-based powder (B) that is solid at room temperature can be easily applied to the rotating body by heating and melting it during use, (ii) the moisture-curable adhesive quickly solidifies after application, allowing the balance (equilibrium) of the entire rotating body to be quickly confirmed, and (iii) moisture (water) in the air promotes a crosslinking reaction of the moisture-curable adhesive, thereby sufficiently improving adhesion to the rotating body. This is described in detail below.

[0010] [Definitions and meanings of terms] The definitions and meanings of terms used in this specification are as follows. "Room temperature" or "room temperature" refers to a temperature of 23°C. "A moisture-curable adhesive that is solid at room temperature" refers to a moisture-curable adhesive that is crystalline, partially crystalline, or glassy amorphous, and has a softening point or melting point measured by the ring and ball method of more than 23°C. "Melting point" refers to the maximum value of the curve measured during a heating operation, for example, by dynamic differential calorimetry (differential scanning calorimetry: DSC), and refers to the temperature at which the adhesive transitions from a solid state to a liquid state. "Moisture-curable adhesive" refers to an adhesive that cures by chemically reacting with water or water vapor.

[0011] [Balance Weight Composition] <Moisture-Curable Adhesive (A) That Is Solid at Room Temperature> The "moisture-curable adhesive (A) that is solid at room temperature," which is a component of the balance weight composition of the present invention, is solid (having a softening point or melting point measured by the Ring and Ball method exceeding 23°C) at room temperature (23°C) and standard atmospheric pressure (1013.25 hPa), and is an adhesive that cures by chemically reacting with water or water vapor. As the "moisture-curable adhesive (A) that is solid at room temperature," for example, adhesives known as "reactive hot melt adhesives" or "one-component moisture-curable reactive hot melt adhesives" can be used.

[0012] Examples of the moisture-curable adhesive (A) that is solid at room temperature include adhesives containing an isocyanate group-containing urethane prepolymer Aa as a main component, and adhesives containing a crosslinkable silicon group-containing polymer Ab as a main component.

[0013] (Isocyanate Group-Containing Urethane Prepolymer Aa) The isocyanate group-containing urethane prepolymer Aa may be produced by any method, provided that it is a prepolymer having an isocyanate group. For example, it can be obtained by reacting a polyisocyanate component with a polyol component so that the polyisocyanate component is in excess. For example, the molar ratio of isocyanate groups in the polyisocyanate component to hydroxyl groups in the polyol component, i.e., isocyanate groups / hydroxyl groups, is greater than 1.0, preferably 1.2 or more, more preferably 1.3 or more, and even more preferably 1.4 or more, and is, for example, 2.5 or less, preferably 2.3 or less, and more preferably 2.1 or less. The isocyanate group / hydroxyl group ratio is preferably 1.2 or more to ensure good coating properties, and is preferably 2.5 or less to ensure good curing properties.

[0014] {Polyisocyanate Component} The polyisocyanate component is not particularly limited as long as it is a compound having at least two isocyanate groups in one molecule, and examples thereof include one or more compounds selected from the group consisting of aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of these polyisocyanates.

[0015] Examples of the aliphatic polyisocyanate include those having an aliphatic hydrocarbon group having 1 to 20 carbon atoms. For example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate, lysine diisocyanate (2,6-diisocyanate), aliphatic diisocyanates such as 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, and 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyloctane; and the like.

[0016] The alicyclic polyisocyanate may, for example, be one having an alicyclic hydrocarbon group having 3 to 20 carbon atoms. For example, alicyclic diisocyanates such as 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, isophorone diisocyanate, 4-methyl-1,3-cyclohexylene diisocyanate (hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or a mixture thereof (hydrogenated xylylene diisocyanate), dicyclohexylmethane diisocyanate (hydrogenated MDI), and norbornane diisocyanate; 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 2-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, cyanatopropyl)-2,6-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 6-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3- alicyclic triisocyanates such as 5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, and 6-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane; and the like.

[0017] Examples of the araliphatic polyisocyanate include one or more selected from the group consisting of araliphatic diisocyanates such as 1,3- or 1,4-xylylene diisocyanate or a mixture thereof (XDI), ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (tetramethylxylylene diisocyanate) or a mixture thereof; and araliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene.

[0018] Examples of aromatic polyisocyanates include m- or p-phenylene diisocyanate, diphenylmethane diisocyanate (MDI), 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), a mixture of 2,4-TDI and 2,6-TDI, 4,4'-toluidine diisocyanate, and 4,4'-diphenyl ether diisocyanate. aromatic diisocyanates; aromatic triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene; aromatic tetraisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate, and aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI); and the like.

[0019] Examples of the derivatives of polyisocyanates include dimers, trimers, biurets, allophanates, uretdione, uretimine, isocyanurates, and oxadiazinetriones of the above polyisocyanates.

[0020] Among these, preferred is one or more selected from the group consisting of phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene isocyanate, etc. From the viewpoint of producing a hot melt adhesive that is used by heating and melting, diphenylmethane diisocyanate, which has a low vapor pressure when heated, is particularly preferred.

[0021] {Polyol} The polyol component is not particularly limited as long as it is a compound having at least two hydroxyl groups per molecule. The polyol component may be either a low-molecular-weight polyol or a high-molecular-weight polyol (polymer polyol). To obtain the isocyanate group-containing urethane prepolymer Aa constituting the moisture-curable adhesive of the present invention that is solid at room temperature, it is preferable that the polyol component contain at least one polyester polyol that has at least two hydroxyl groups and is solid at room temperature, particularly an at least partially crystalline solid. This allows the moisture-curable adhesive to solidify quickly after application, making it possible to quickly confirm the balance (equilibrium) of the entire rotating body. In the present invention, the polyol component may also be an acrylic polyol and / or a polycarbonate polyol that is solid at room temperature. Furthermore, to improve application properties and impart flexibility after moisture curing, the polyol component may also be one or more polyols that are liquid at room temperature, such as polyether polyols, polyester polyols, polyolefin polyols, and castor oil polyols.

[0022] -Polyester polyols that are solid at room temperature- A polyester polyol that is solid at room temperature is a polyol having two or more hydroxyl groups and a polyester repeating unit per molecule. A polyester polyol can be obtained, for example, by reacting a polyol component having two or more hydroxyl groups with a polycarboxylic acid component having two or more carboxyl groups or reactive derivatives thereof, in an excess amount of the polyol component. Alternatively, a polyester polyol can be obtained by linking polyester polyols with diisocyanates. Alternatively, a polyester polyol can be obtained by ring-opening polymerization of a cyclic polyester such as a polycaprolactone derivative using a bifunctional starter molecule such as 1,6-hexanediol.

[0023] Examples of polyol components having two or more, preferably two or three, more preferably two hydroxyl groups include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol, 1,3-butanediol, 2,2-diethyl-1,3-propanediol, 2,2-diethylpropanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-methyl-1,8-octanediol, and the like. and 2,4-diethyl-1,5-pentanediol; aliphatic diols having an ether bond such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol; aromatic diols obtained by subjecting bisphenol compounds such as bisphenol A and bisphenol F to a ring-opening addition reaction with ethylene oxide, propylene oxide, γ-butyrolactone, ε-caprolactone, or the like; and aliphatic triols such as trimethylolethane, trimethylolpropane, pentaerythritol, and glycerin. Among these, preferred is one or more selected from the group consisting of linear aliphatic diols having 2 to 14 carbon atoms, preferably 2 to 12 carbon atoms, because this can enhance the crystallinity of the resulting polyester polyol.

[0024] Examples of polycarboxylic acid components having two or more carboxyl groups or reactive derivatives thereof include one or more selected from the group consisting of straight-chain aliphatic dicarboxylic acids having from 2 to 16 carbon atoms, such as oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and 1,12-dodecanedicarboxylic acid; aromatic dicarboxylic acids having 8 or more carbon atoms, such as terephthalic acid, isophthalic acid, terephthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, and biphenyldicarboxylic acid; and reactive derivatives thereof (acid halides, acid anhydrides, acid esters, etc.). Among these, one or more selected from the group consisting of straight-chain aliphatic dicarboxylic acids having from 6 to 14 carbon atoms, preferably from 8 to 12 carbon atoms, or reactive derivatives thereof are preferred, as they can enhance the crystallinity of the resulting polyester polyol.

[0025] {Acrylic Polyol Solid at Room Temperature} Examples of acrylic polyols that are solid at room temperature include (meth)acrylic polymers having hydroxyl groups and acrylic polymers with hydroxyl groups introduced at their terminals. The inclusion of an acrylic polyol can adjust the solidification time of the balance weight composition and can toughen the cured product after moisture curing.

[0026] {Polycarbonate polyol solid at room temperature} As the polycarbonate polyol solid at room temperature, for example, a polycarbonate polyol obtained by reacting a carbonate ester and / or phosgene with a diol can be used, which can improve the hydrolysis resistance and moisture-resistant adhesion of the balance weight composition cured product.

[0027] Examples of the carbonate ester include one or more selected from the group consisting of dimethyl carbonate, diphenyl carbonate, and the like.

[0028] Examples of diols include one or more selected from the group consisting of straight-chain aliphatic diols such as 1,5-pentanediol, 1,6-hexanediol, and 1,9-nonanediol; branched-chain aliphatic diols such as neopentyl glycol, 3-methyl-1,5-pentanediol, and 2-methyl-1,8-octanediol; alicyclic diols such as 1,4-cyclohexanedimethanol; and aromatic diols such as bisphenol A. Polycarbonate polyols containing only one type of straight-chain aliphatic diol are solid at room temperature and have crystallinity. In the present invention, it is preferable to use a polycarbonate polyol containing only 1,6-hexanediol.

[0029] {Polyol that is liquid at room temperature} In the present invention, the polyol component may contain a polyol that is liquid at room temperature, as necessary. Examples of the polyol that is liquid at room temperature include one or more selected from the group consisting of polyether polyols, aromatic polyester polyols, polycarbonate polyols, etc.

[0030] -Polyether polyol- Examples of polyether polyols that are liquid at room temperature include one or more selected from the group consisting of polypropylene glycol (PPG), polyethylene glycol (PEG), polytetramethylene glycol (PTMG), etc. The number average molecular weight of the polyether polyol is not particularly limited. For example, it is 500 or more, preferably 1,000 or more, more preferably 2,000 or more, and for example, it is 30,000 or less, preferably 20,000 or less, more preferably 15,000 or less.

[0031] The polyether polyol is preferably a diol. Alternatively, a compound obtained by copolymerizing two or more polyether polyols may be used as the polyether polyol. For example, a polyoxyethylene-oxypropylene block copolymer diol may be mentioned. Such a diol is preferred because its terminal group is a primary hydroxyl group and it has good reactivity with an isocyanate group. The polyoxyethylene-oxypropylene block copolymer diol preferably has an ethylene oxide content of 5% by weight or more, preferably 90% by weight or less, more preferably 40% by weight or less, and even more preferably 20% by weight or less.

[0032] -Polyester Polyol- Examples of polyester polyols that are liquid at room temperature include one or more selected from the group consisting of aromatic polyester polyols, alicyclic polyester polyols, aliphatic polyester polyols, etc. For example, by mixing and using an aromatic polyester polyol that is liquid at room temperature, a moisture-curing adhesive that is solid at room temperature and has excellent adhesive strength can be obtained.

[0033] The polyester polyol that is liquid at room temperature may be, for example, a mixture of an aromatic polyester polyol having a number average molecular weight of 2,000 or more and 5,000 or less and a glass transition temperature of 30°C or more, and an aromatic polyester polyol having a number average molecular weight of 400 or more and 3,500 or less and a glass transition temperature of 20°C or less.

[0034] The glass transition temperature (Tg) of the polyester polyol is not particularly limited, but is preferably 20° C. or lower and preferably −30° C. or higher, from the viewpoint of further improving adhesiveness.

[0035] -Polycarbonate polyol- Examples of polycarbonate polyols that are liquid at room temperature include copolymer polycarbonate diols whose glycol component is composed of 3-methyl-1,5-pentanediol and 1,6-hexanediol, copolymer polycarbonate diols composed of 1,5-pentanediol and 1,6-hexanediol, copolymer polycarbonate diols composed of 2-methyl-1,8-octanediol and 1,9-nonanediol, etc. Use of these polycarbonate polyols that are liquid at room temperature can improve the flexibility of the cured coating of the moisture-curable adhesive that is solid at room temperature according to the present invention.

[0036] The number average molecular weight of the polycarbonate polyol is preferably 500 or more, more preferably 1,000 or more, and is preferably 5,000 or less, more preferably 4,000 or less, from the viewpoint of further improving the adhesiveness of the moisture-curable adhesive according to the present invention that is solid at room temperature.

[0037] The glass transition temperature (Tg) of the polycarbonate polyol is not particularly limited, but is preferably 20°C or lower and preferably -30°C or higher from the viewpoint of further improving adhesiveness.

[0038] (Crosslinkable Silicon Group-Containing Polymer Ab) The crosslinkable silicon group-containing polymer Ab according to the present invention is not particularly limited as long as it is a polymer containing a crosslinkable silicon group in the molecule. For example, it can be obtained by reacting the isocyanate group of an isocyanate group-containing urethane prepolymer Aa with a compound having a functional group reactive with an isocyanate group and a crosslinkable silicon group. It can also be obtained by reacting a polymer or compound having a functional group reactive with an isocyanate group with a polymer or compound having an isocyanate group and a crosslinkable silicon group. Here, the functional group reactive with an isocyanate group is an active hydrogen-containing group such as a hydroxyl group, an amino group, or a mercapto group, and the crosslinkable silicon group is an alkoxysilyl group, a silanol group, or the like.

[0039] Examples of compounds having a functional group reactive with an isocyanate group and a crosslinkable silicon group include silane coupling agents having a functional group reactive with an isocyanate group, such as an amino group, a hydroxyl group, or a mercapto group.

[0040] Examples of silane coupling agents having a functional group that reacts with an isocyanate group include at least one selected from the group consisting of mercaptosilanes such as γ-mercaptopropyltrimethoxysilane; hydroxyl group-containing silanes such as 2-ethoxy-4(5)-(2-triethoxysilylethyl)cyclohexane-1-ol; primary aminosilanes such as 3-aminopropyltrimethoxysilane; secondary aminosilanes such as N-butyl-3-aminopropyltrimethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane; Michael-type adducts of primary aminosilanes such as N-(3-trimethoxysilylpropyl)aminosuccinate dimethyl and diethyl ester; and analogs of the above aminosilanes having an alkoxy group having 1 to 6 carbon atoms, such as an ethoxy or isopropoxy group, instead of the methoxy group bonded to the silicon atom.

[0041] In the present invention, it is preferable to use a secondary aminosilane, because it reacts relatively slowly with an isocyanate group compared to a primary aminosilane, etc., and therefore the target compound can be easily obtained.

[0042] In addition to the above polymers, the crosslinkable silicon group-containing polymer Ab according to the present invention can also be one or more of the following: a crosslinkable silicon group-containing (meth)acrylic polymer obtained by reacting a polymer or compound having an isocyanate group with a (meth)acrylic polymer having a functional group reactive with an isocyanate group and a crosslinkable silicon group, or a crosslinkable silicon group-containing (meth)acrylic polymer obtained by reacting a polymer or compound having an isocyanate group and a (meth)acrylic polymer having a functional group reactive with an isocyanate group.Here, the functional group reactive with an isocyanate group is an active hydrogen-containing group such as a hydroxyl group, an amino group, or a mercapto group, and the crosslinkable silicon group is an alkoxysilyl group, a silanol group, or the like.

[0043] Examples of (meth)acrylic polymers having a functional group reactive with an isocyanate group and a crosslinkable silicon group, and (meth)acrylic polymers having a functional group reactive with an isocyanate group, include (meth)acrylic copolymers obtained by polymerizing a monomer component containing a monomer having a functional group reactive with an isocyanate group, such as a hydroxyl group. It is particularly preferable to use a (meth)acrylic polymer containing a crosslinkable silicon group and a hydroxyl group at its terminal, which is solid at room temperature (23°C). This polymer has a "(hard segment)-(soft segment)-(hard segment)" type block polymer structure composed of a "hard segment" such as a methyl (meth)acrylate copolymer that is solid at room temperature and a "soft segment" such as a polyether or crystalline polyester, thereby improving toughness. Furthermore, the inclusion of a crosslinkable silicon group such as an alkoxysilyl group promotes the crosslinking reaction, further improving adhesion and heat resistance.

[0044] The crosslinkable silicon group-containing (meth)acrylic polymer preferably has one hydroxyl group. Using a crosslinkable silicon group-containing (meth)acrylic polymer having only one hydroxyl group can suppress gelation of moisture-curable adhesives that are solid at room temperature. The method for introducing hydroxyl groups into the crosslinkable silicon group-containing (meth)acrylic polymer is not particularly limited. Examples include the following methods. The hydroxyl groups may be introduced at positions other than the terminals. (1) Copolymerizing an unsaturated compound having a hydroxyl group. (2) Polymerizing using an initiator or chain transfer agent having a hydroxyl group. (3) Reaction using a thiol compound having a hydroxyl group, or polymerization using a thiol compound having a hydroxyl group and a metallocene compound. The method described in Japanese Patent No. 5222467 can be used for method (3). As a method for introducing hydroxyl groups, from the viewpoint of being able to introduce one hydroxyl group, polymerization using a thiol compound having a hydroxyl group and a metallocene compound is preferred. An example of a thiol compound having a hydroxyl group is 2-mercaptoethanol.

[0045] The number average molecular weight of the crosslinkable silicon group-containing (meth)acrylic polymer is not particularly limited and is, for example, 1,000 or more, preferably 2,000 or more, more preferably 3,000 or more, and for example, 50,000 or less, preferably 30,000 or less, more preferably 15,000 or less.

[0046] As a monomer having a functional group, such as a hydroxyl group, that reacts with an isocyanate group, which is a constituent monomer of the crosslinkable silicon group-containing (meth)acrylic polymer, a hydroxyl group-containing (meth)acrylic alkyl ester is preferred. Examples of such compounds include one or more selected from the group consisting of monohydroxyacrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl acrylate; and polyhydroxyacrylates such as glycerin mono(meth)acrylate. Among these, monohydroxyacrylates such as 2-hydroxyethyl (meth)acrylate are preferred. The amount of the hydroxyl group-containing (meth)acrylic alkyl ester used is preferably an amount that results in an average of 0.5 to 3 hydroxyl groups, and more preferably 1.1 to 2 hydroxyl groups, per molecule of the crosslinkable silicon group-containing (meth)acrylic polymer.

[0047] In the present invention, when preparing the crosslinkable silicon group-containing polymer Ab, the number of silyl groups in the crosslinkable silicon group-containing polymer Ab can be adjusted (reduced) by using a compound having one functional group reactive with an isocyanate group and no crosslinkable silicon group. This allows the crosslink density after the crosslinkable silicon group-containing polymer Ab has cured to be adjusted, and as a result, the flexibility and / or elongation of the cured coating can be adjusted. Here, examples of functional groups reactive with isocyanate groups include hydroxyl groups, amino groups, and mercapto groups. Hydroxyl groups and amino groups are preferred, and from the viewpoint of stably producing a moisture-curable adhesive that is solid at room temperature, secondary amino groups are more preferred.

[0048] Examples of compounds having one functional group reactive with an isocyanate group and no crosslinkable silicon group include one or more selected from the group consisting of linear or branched monoalkyl alcohols such as 2-ethylhexanol, lauryl alcohol, stearyl alcohol, and behenyl alcohol; ether alcohols or ester alcohols such as propylene glycol monoacetate, diethylene glycol monoacetate, and polyoxypropylene monool; primary monoamines such as octylamine, dodecylamine, cetylamine, stearylamine, and behenylamine; and secondary monoamines such as dibutylamine, butyloctylamine, dioctylamine, distearylamine, and butylstearylamine.

[0049] The number of crosslinkable silicon groups per molecule of the crosslinkable silicon group-containing polymer Ab is preferably 1.0 or more, more preferably 1.2 or more, even more preferably 1.4 or more, and particularly preferably 1.6 or more, on average, from the viewpoint of curability, and is preferably 4.0 or less, more preferably 3.0 or less, even more preferably 2.5 or less, and particularly preferably 2.0 or less, on average, from the viewpoint of physical properties.

[0050] The crosslinkable silicon group-containing polymer Ab according to the present invention may be a moisture-curable (meth)acrylic compound that is solid at room temperature. For example, a crosslinkable silicon group-containing (meth)acrylic polymer is preferably used.

[0051] The glass transition temperature of the crosslinkable silicon group-containing (meth)acrylic polymer is, for example, -20°C or higher, preferably -10°C or higher, and for example, 120°C or lower, preferably 100°C or lower. The crosslinkable silicon group of the crosslinkable silicon group-containing (meth)acrylic polymer is, for example, a group that has a crosslinkable group such as an alkoxy group bonded to a silicon atom and can be crosslinked by a silanol condensation reaction. Examples of the crosslinkable silicon group include groups represented by the following general formula (I):

[0052]

[0053] In general formula (I), R １１represents an alkyl group having 1 to 20 carbon atoms, a substituted alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; R １１ When two or more X's are present, they may be the same or different. X represents an alkoxy group, and when two or more X's are present, they may be the same or different. a represents 0, 1, 2, or 3. In the crosslinkable silicon group of general formula (I), a is preferably 2 or 3. When a is 3, the curing rate is higher than when a is 2. In the case of the crosslinkable silicon group represented by general formula (I), a is preferably 2 or more in consideration of curability.

[0054] R １１ Specific examples of the alkyl group include alkyl groups such as methyl and ethyl groups, substituted alkyl groups such as methoxymethyl groups, and cycloalkyl groups such as cyclohexyl groups. Of these, the methyl group is preferred.

[0055] The alkoxy group represented by X is not particularly limited and may be any conventionally known alkoxy group. Among alkoxy groups, groups with fewer carbon atoms have higher reactivity, and the reactivity decreases as the number of carbon atoms increases, in the order of methoxy group > ethoxy group > propoxy group. While the alkoxy group can be selected depending on the purpose and application, methoxy and ethoxy groups are typically used. Specifically, as the crosslinkable silicon group, alkoxysilyl groups, such as trimethoxysilyl and triethoxysilyl groups, are preferred due to their high reactivity, with trimethoxysilyl groups being more preferred. When a flexible cured product is required, methyldimethoxysilyl and methyldiethoxysilyl groups are preferred. The crosslinkable silicon groups can be used alone or in combination of two or more. The crosslinkable silicon groups may be present in the main chain, side chain, or both.

[0056] Radical polymerization can be used as a polymerization method for producing a crosslinkable silicon group-containing (meth)acrylic polymer. For example, conventional solution polymerization or bulk polymerization methods using thermal polymerization initiators such as benzoyl peroxide or azobisisobutyronitrile can be used. Polymerization methods using a photopolymerization initiator and irradiation with light or radiation can also be used. In radical copolymerization, chain transfer agents such as lauryl mercaptan or 3-mercaptopropyltrimethoxysilane can be used to adjust the molecular weight. Radical polymerization methods using thermal polymerization initiators can also be used, and such methods can easily produce the crosslinkable silicon group-containing (meth)acrylic polymer of the present invention. Other polymerization methods, such as living radical polymerization as described in JP 2000-086998 A, can also be used.

[0057] As the moisture-curable adhesive (A) that is solid at room temperature, a crosslinkable silicon group-containing polymer (a2) is preferred to an isocyanate group-containing urethane prepolymer (a1) from the viewpoint that it is less likely to thicken when heated when used as a balance weight.

[0058] (Silane-based adhesion promoter) The moisture-curable adhesive (A) according to the present invention that is solid at room temperature may further contain a silane-based adhesion promoter. The silane-based adhesion promoter exerts an adhesion promoter effect upon moisture curing, and can improve adhesion to a rotating body, water-resistant adhesion, and heat-resistant adhesion after moisture curing.

[0059] From the viewpoint of hydrolysis rate, the crosslinkable silicon group of the silane adhesion promoter is preferably an alkoxysilyl group having 1 to 6 carbon atoms, such as a methoxy group or an ethoxy group. The number of alkoxy groups in the alkoxysilyl group is preferably 2 or more, more preferably 3. The silane adhesion promoter may also have a functional group. From the viewpoint of adhesiveness, preferred functional groups include amino groups and epoxy groups, with amino groups being more preferred.

[0060] Examples of silane-based adhesion promoters include aminosilanes such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(β-aminoethyl)-3-aminopropyltrimethoxysilane, N-(β-aminoethyl)-3-aminopropyltriethoxysilane, N-(β-aminoethyl)-3-aminopropylmethyldiethoxysilane, bis-(trimethoxysilylpropyl)amine, bis-(triethoxysilylpropyl)amine, bis-(triethoxysilylpropyl)ethylenediamine, N-[2-(vinylbenzylamino)ethyl]-3-aminopropyltrimethoxysilane, and aminoethyl-aminopropyltrimethoxysilane; ketimine-based silanes such as N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxy ...

[0039] Specific examples of the silane include epoxy silanes such as glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane; (meth)acrylic silanes such as 3-methacryloxypropyltrimethoxysilane; vinyl silanes such as vinyltrimethoxysilane, methylvinyldimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, and allyltri(β-methoxysilane); mercaptosilanes such as 3-mercaptopropyltrimethoxysilane; urea silanes such as 3-ureidopropyltrimethoxysilane and 3-ureidopropyltriethoxysilane; isocyanurate silanes such as tris-(trimethoxysilylpropyl)isocyanurate; and isocyanate silanes such as 3-isocyanatepropyltriethoxysilane.

[0061] The silane-based adhesion promoter may be at least one selected from the group consisting of the reaction products of the above aminosilanes and epoxysilanes, the reaction products of aminosilanes and isocyanatesilanes, the reaction products of aminosilanes and silanes having a (meth)acryloyloxy group, the reaction products of aminosilanes and epoxy resins (such as bisphenol A diglycidyl ether and phenyl glycidyl ether), the reaction products of aminosilanes and polyisocyanates, the reaction products of aminosilanes and polyacrylates, condensates obtained by partially condensing the above silanes (preferably aminosilane condensates obtained by partially condensing the above aminosilanes, isocyanatesilanes, aminosilane reactants, and mixtures of the reactants), modified derivatives thereof, amino-modified silyl polymers, crosslinkable silicon group-containing aminopolymers, unsaturated aminosilane complexes, phenylamino long-chain alkylsilanes, crosslinkable silicon group-containing aminosilicones, crosslinkable silicon group-containing polyesters, photoaminosilane generators, and the like.

[0062] The molecular weight of the silane adhesion promoter is not particularly limited. For example, a molecular weight of 320 or more, preferably 400 or more, more preferably 450 or more is preferred because it is less likely to volatilize when a moisture-curable adhesive that is solid at room temperature is melted. Silane adhesion promoters having two or more silyl groups, such as bis-silylaminosilane, isocyanurate silane, aminosilane reactants, and aminosilane condensates, are preferred because of their adhesiveness and less likely to volatilize when the hot-melt adhesive is melted, with aminosilane reactants and aminosilane condensates being more preferred, and aminosilane reactants being most preferred. Note that the aminosilane reactant may be reacted by separately adding reactive materials during the mixing process.

[0063] The silane adhesion promoter may be used alone or in combination of two or more. The amount of the silane adhesion promoter used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, particularly preferably 1 part by mass or more, and preferably 20 parts by mass or less, more preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, relative to 100 parts by mass of the isocyanate group-containing urethane prepolymer or the crosslinkable silicon group-containing polymer. If the amount is less than 0.01 parts by mass, the adhesion-imparting effect and the effect as a curing catalyst are insufficient, while if the amount exceeds 20 parts by mass, the catalytic action corresponding to the added amount is not significant, which is economically undesirable.

[0064] (Crosslinking Catalyst) The moisture-curable adhesive (A) according to the present invention that is solid at room temperature may contain a crosslinking catalyst. Examples of crosslinking catalysts that can be used include crosslinking catalysts (silanol catalysts) for crosslinkable silicon-containing polymers. Examples of crosslinking catalysts include titanate esters, tetravalent organotin compounds, divalent organotin compounds such as tin octoate, zirconium compounds, aluminum compounds, bismuth compounds, primary and secondary amine compounds, tertiary amine compounds such as benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, dimorpholinodiethyl ether, N,N-dimethyldodecylamine, and bis-(N,N'-dimethylaminoethyl)ether, photolatent amine compounds (photobase generators), amidine compounds such as 1,3-diazabicyclo(5,4,6)undecene-7, or carboxylates thereof, and fluorinated polymers.

[0065] Examples of fluorinated polymers include organic polymers having Si—F bonds, such as the organic polymers having fluorosilyl groups described in WO 2015 / 088021. As the fluorinated polymer, preferred are polymers having fluorosilyl groups, such as difluoromethylsilyl groups, difluoromethoxysilyl groups, difluoroethoxysilyl groups, and trifluorosilyl groups, at the end of the main chain or side chain. The polymers described in the liquid polymer compound section below can be used as the main chain skeleton of the fluorinated polymer. Among these polymers, polyoxyalkylene polymers and / or (meth)acrylic acid ester polymers are preferred because they are easy to handle and have a significant effect of extending the bonding time. The number average molecular weight of the fluorinated polymer, as measured by GPC in terms of polystyrene, is preferably 3,000 or more, preferably 100,000 or less, more preferably 50,000 or less, and particularly preferably 30,000 or less.

[0066] When the moisture-curable adhesive (A) according to the present invention that is solid at room temperature contains a crosslinking catalyst, the content of the crosslinking catalyst is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the crosslinkable silicon group-containing polymer, and is, for example, 10 parts by mass or less, preferably 7 parts by mass or less, and more preferably 5 parts by mass or less.

[0067] (Modified Resin) The moisture-curable adhesive (A) according to the present invention, which is solid at room temperature, may contain a modified resin for adjusting the solidification time, reducing the melt viscosity, improving and adjusting various physical properties, etc. The modified resin exhibits different functions depending on the type of segment constituting the target resin. That is, when the modified resin is added to a resin mainly composed of hard segments, it exhibits the function of adjusting physical properties as a modified resin, and when added to a resin mainly composed of soft segments, it exhibits the function of a tackifying resin. In particular, since the skeleton of the crosslinkable silicon group-containing polymer is mainly composed of hard segments, the resins exemplified below act as modified resins.

[0068] Examples of modified resins include terpene resins, aromatic modified terpene resins, hydrogenated terpene resins, terpene-phenolic resins copolymerized with terpenes and phenols, phenolic resins, modified phenolic resins, xylene-phenolic resins, cyclopentadiene-phenolic resins, coumarone-indene resins, rosin resins, rosin ester resins, hydrogenated rosin ester resins, xylene resins, low molecular weight polystyrene resins, styrene copolymer resins, styrene block copolymers, hydrogenated styrene block copolymers, petroleum resins (e.g., C5 hydrocarbon resins, C9 hydrocarbon resins, C5C9 hydrocarbon copolymer resins, etc.), hydrogenated petroleum resins, and DCPD resins. At least one selected from the group consisting of resins and the like can be mentioned.

[0069] In the present invention, styrene-based block copolymers and hydrogenated products thereof are preferred. Examples of the styrene-based block copolymers and hydrogenated products thereof include one or more selected from the group consisting of styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylenebutylene-styrene block copolymer (SEBS), styrene-ethylenepropylene-styrene block copolymer (SEPS), and styrene-isobutylene-styrene block copolymer (SIBS).

[0070] As the modifying resin, terpene phenol resins and aromatic petroleum resins are preferred from the viewpoints of good compatibility with crosslinkable silicon group-containing polymers and good heat stability of the adhesive. As the aromatic petroleum resin, aromatic styrene resins and aliphatic-aromatic copolymer styrene resins are preferred, and terpene phenol resins and aliphatic-aromatic copolymer styrene resins are more preferred. Furthermore, from the viewpoints of VOCs and fogging, it is preferable to use aliphatic-aromatic copolymer styrene resins.

[0071] (Liquid Polymer Compound) The moisture-curable adhesive (A) according to the present invention that is solid at room temperature may contain a liquid polymer compound for adjusting the viscosity during melting and the solidification time. The liquid polymer compound has a viscosity (as measured by a Brookfield viscometer) at room temperature (23°C) of 200 Pa s or less, preferably 150 Pa s or less, and more preferably 100 Pa s or less.

[0072] Examples of the main chain skeleton of the liquid polymer compound include polyoxyalkylene polymers such as polyoxypropylene, polyoxytetramethylene, and polyoxyethylene-polyoxypropylene copolymers; hydrocarbon polymers such as ethylene-propylene polymers, polyisobutylene, polyisoprene, polybutadiene, and hydrogenated polyolefin polymers obtained by hydrogenating these polyolefin polymers; polyester polymers obtained by condensation of dibasic acids such as adipic acid with glycols or ring-opening polymerization of lactones; (meth)acrylic acid ester polymers obtained by radical polymerization of monomers such as ethyl (meth)acrylate and butyl (meth)acrylate; vinyl polymers obtained by radical polymerization of monomers such as (meth)acrylic acid ester monomers, vinyl acetate, acrylonitrile, and styrene; graft polymers obtained by polymerizing vinyl monomers in organic polymers; polysulfide polymers; polyamide polymers; polycarbonate polymers; and diallyl phthalate polymers. Two or more of these skeletons may be contained in a block or random configuration. Among these polymers, polyoxyalkylene polymers and / or (meth)acrylic acid ester polymers are preferred from the viewpoint of ease of handling. The liquid polymer compound may have a moisture-curable functional group such as an isocyanate group-containing urethane prepolymer or a crosslinkable silicon group-containing polymer, from the viewpoint of imparting heat resistance by moisture curing after application of the balance weight.

[0073] The crosslinkable silicon group of the crosslinkable silicon group-containing polymer may be bonded to the main chain or side chain of the polymer, or both.From the viewpoint of excellent physical properties of the cured product, such as tensile properties, it is preferable that the crosslinkable silicon group is present at the molecular chain end.The crosslinkable silicon group-containing polymer is mixed for the purpose of adjusting the solidification time of the moisture-curable adhesive (A) that is solid at room temperature and reducing the melt viscosity, and has the function of modifying and / or adjusting the physical properties.

[0074] (Other Components) The moisture-curable adhesive (A) of the present invention that is solid at room temperature may contain "other components" such as a filler, a diluent, a stabilizer, and the like.

[0075] {Filler} Examples of fillers include inorganic fillers such as calcium carbonate, magnesium carbonate, titanium oxide, carbon black, fused silica, precipitated silica, diatomaceous earth, white clay, kaolin, clay, talc, wood flour, walnut shell powder, rice husk powder, silicic anhydride, quartz powder, aluminum powder, zinc powder, iron powder, asbestos, glass fiber, carbon fiber, glass beads, aluminum hydroxide, alumina, glass balloons, shirasu balloons, silica balloons, calcium oxide, magnesium oxide, and silicon oxide, as well as organic fillers such as wood fillers such as pulp and cotton chips, powdered rubber, reclaimed rubber, fine powder of thermoplastic or thermosetting resin, and hollow bodies such as polyethylene. Only one type of filler may be added, or multiple types may be added in combination.

[0076] {Diluent} By adding a diluent, physical properties such as viscosity at the time of melting can be adjusted. As the use temperature (application, melting) of the adhesive is high, it is preferable to use a solvent (diluent) with a boiling point of 150°C or higher, taking into consideration the viewpoint of safety (fire, health). The boiling point of the diluent is preferably 150°C or higher, more preferably 200°C or higher, and even more preferably 300°C or higher. In the present invention, it is preferable not to use a diluent with a boiling point of 120°C or lower, preferably not to use a diluent with a boiling point of 150°C or lower, and more preferably not to use a diluent with a boiling point of 200°C or lower.

[0077] Examples of diluents include phthalates such as dioctyl phthalate and diisodecyl phthalate; aliphatic dibasic acid esters such as dimethyl adipate and dioctyl adipate; polyethers such as polypropylene glycol and its derivatives; vinyl polymers obtained by polymerizing vinyl monomers by various methods; oils such as paraffinic process oil and naphthenic oil; synthetic waxes such as Fischer-Tropsch wax, polyethylene wax, polypropylene wax, and atactic polypropylene; petroleum waxes such as paraffin wax and microcrystalline wax; etc. These diluents can be used alone or in combination of two or more.

[0078] {Stabilizer} Examples of stabilizers include one or more selected from the group consisting of antioxidants, light stabilizers, ultraviolet absorbers, etc. The inclusion of an antioxidant can improve the weather resistance and heat resistance of the cured product of the balance weight composition. Examples of antioxidants include one or more selected from the group consisting of hindered phenol-based antioxidants, monophenol-based antioxidants, bisphenol-based antioxidants, polyphenol-based antioxidants, etc. Hindered phenol-based antioxidants are particularly preferred. The inclusion of a light stabilizer can prevent photooxidative degradation of the cured product of the balance weight composition. Examples of light stabilizers include one or more selected from the group consisting of benzotriazole-based light stabilizers, hindered amine-based light stabilizers, benzoate-based light stabilizers, etc. Hindered amine-based light stabilizers are particularly preferred. The inclusion of a light stabilizer can improve the surface weather resistance of the cured product of the balance weight composition. Examples of the ultraviolet absorber include one or more selected from the group consisting of benzophenone-based light stabilizers, benzotriazole-based light stabilizers, salicylate-based light stabilizers, substituted tolyl-based light stabilizers, and metal chelate compounds. Benzotriazole-based light stabilizers are particularly preferred. As the stabilizer, for example, it is preferred to use a phenol-based antioxidant or hindered phenol-based antioxidant in combination with a hindered amine-based light stabilizer and a benzotriazole-based ultraviolet absorber.

[0079] <Tungsten-based powder (B)> Tungsten-based powder (B) is not particularly limited as long as it is a powder that is mainly composed of tungsten.For example, one or more selected from the group consisting of tungsten powder, tungsten alloy powder, and tungsten compound powder can be used.For example, tungsten alloy powder can be one or more tungsten alloy powders that are mainly composed of tungsten and include one or more selected from the group consisting of iron, copper, nickel, etc.For example, tungsten compound powder can be one or more selected from the group consisting of tungsten carbide (tungsten carbide), tungsten oxide, and ceramics that are mainly composed of tungsten.

[0080] In the present invention, the particle size of the tungsten-based powder (B) is not particularly limited. For example, it is 0.1 μm or more, preferably 1.0 μm or more, more preferably 2.0 μm or more, and for example, it is 100.0 μm or less, preferably 80.0 μm or less, more preferably 60.0 μm or less. If the particle size of the tungsten-based powder (B) is less than 0.05 μm, the viscosity of the balance weight composition when heated and melted is likely to increase, which may reduce workability. If the particle size of the tungsten-based powder (B) is more than 100 μm, sedimentation of the tungsten-based powder (B) may easily occur when the balance weight composition is heated and melted. In the present invention, tungsten-based particles (B) of different particle sizes within the particle size range of 0.1 to 100 μm may be used in combination as the tungsten-based particles (B).

[0081] In the present invention, the specific gravity of the tungsten-based powder is not particularly limited, and is, for example, 10.0 or more, preferably 11.0 or more, more preferably 13.0 or more, and is, for example, 20.5 or less, preferably 20.0 or less, more preferably the specific gravity of tungsten (19.30) or less.

[0082] Among tungsten-based powders, commercially available tungsten powders include, for example, "WH" (particle size: 0.45 to 0.59 μm) and "W-6" (particle size: 8.0 to 16.0 μm) manufactured by Nippon New Metals Co., Ltd., and "A20" (particle size: 0.5 to 0.6 μm) and "W-U250" (particle size: 23 to 28 μm) manufactured by A.L.M.T. Corporation. In the present invention, one or more of these can be used.

[0083] Among tungsten-based powders, commercially available tungsten compound powders include, for example, tungsten carbide powder. Examples of commercially available tungsten carbide powders include "WC-10" (particle size: 0.70 to 1.19 μm) and "WC-90" (particle size: 7.5 to 12.0 μm) manufactured by Japan New Metals Co., Ltd., and "WC08" (particle size: 0.7 to 0.9 μm) and "WC60" (particle size: 5.0 to 7.1 μm) manufactured by A.L.M.T. Corporation. In the present invention, one or more of these can be used.

[0084] <Method for preparing a composition for a balance weight> The balance weight according to the present invention can be prepared, for example, by mixing tungsten (B) during the production of a moisture-curable adhesive (A) that is solid at room temperature.

[0085] There are no particular limitations on the method for preparing the reactive hot melt adhesive of the present invention. For example, conventional methods can be used, such as blending the above-mentioned components in a predetermined blending ratio and kneading them at room temperature or under heat using a mixer, roll, kneader, etc., or dissolving each component in a small amount of a predetermined solvent and mixing them.

[0086] The viscosity of the balance weight according to the present invention at 120°C is preferably 200 Pa·s or less, more preferably 180 Pa·s or less, and even more preferably 160 Pa·s or less. If the viscosity at 120°C exceeds 200 Pa·s, the application properties and workability will be reduced, or it will be necessary to apply the composition at a higher temperature to ensure the application properties and workability. In such cases, the range of use will be limited, for example, it will be difficult to use the composition on substrates with low heat resistance.

[0087] [Balance Weight] The specific gravity of the balance weight according to the present invention is 8.5 or less. The lower limit of the specific gravity of the balance weight is, for example, 2.0 or more, preferably 3.0 or more, and more preferably 4.0 or more. The upper limit of the specific gravity of the balance weight is 8.5 or less, preferably 8.3 or less, more preferably 8.2 or less, and even more preferably 8.0 or less, from the viewpoints of application property and workability. The balance weight according to the present invention is preferably attached to a rotating body, such as the impeller of a fan motor, particularly the rotor of a brushless motor, to adjust the balance. For example, it is preferably used as a balance weight for the impeller (rotor) of a brushless fan motor, which is rotatably supported by a bearing attached to the center of the fan motor body via a rotating shaft. Impellers may have uneven mass distribution around the rotating shaft due to assembly variations, component dimensional variations, manufacturing variations, etc., resulting in imbalance. In such cases, the balance weight according to the present invention can be used to resolve the imbalance.

[0088] The balance weight according to the present invention is obtained by curing a balance weight composition containing a moisture-curable adhesive (A) that is solid at room temperature and tungsten-based particles. The balance weight can be suitably used as an unbalance adjuster for a rotating body by adjusting the specific gravity of the balance weight after moisture curing to 4.0 or more. The balance weight composition instantly solidifies immediately after application, allowing the overall balance to be measured. Furthermore, the crosslinking reaction caused by moisture in the air can sufficiently improve adhesion to the rotating body.

[0089] In the present invention, it is preferable to use tungsten-based particles (B) having a specific gravity of 10.0 or more and a particle size in the range of 0.1 to 100 μm.

[0090] The balance weight of the present invention uses a moisture-curing adhesive (A) that is solid at room temperature. Therefore, immediately after heating, melting, and applying it to the rotating body, the adhesive solidifies when it drops below its softening point or melting point, making it possible to measure the balance of the entire rotating body.

[0091] It is important that the moisture-curable adhesive (A) used in the balance weight according to the present invention, which is solid at room temperature, has a low viscosity when heated and melted. For example, the viscosity when heated to 120°C is preferably 100 Pa s or less, more preferably 50 Pa s or less, and even more preferably 40 Pa s or less.

[0092] <Method for Applying a Balance Weight Using a Moisture-Curing Adhesive That Is Solid at Room Temperature> The method for applying the balance weight of the present invention can be the same as that for various known reactive hot-melt adhesives. For example, the application method includes a step of heating the balance weight of the present invention to a temperature in the range of 50°C to 130°C (heating step), and a step of applying the heated balance weight to the balance adjustment location of the rotating body (application step).

[0093] The balance weight using a moisture-curing adhesive that is solid at room temperature according to the present invention is composed of a moisture-curing adhesive that is solid at room temperature and whose main components are an isocyanate group-containing urethane prepolymer and a cross-linkable silicon group-containing polymer. Therefore, the balance weight solidifies immediately after application, preventing dripping and slippage of the balance weight applied to the rotating body. Furthermore, the use of a moisture-curing adhesive imparts adhesiveness and heat resistance to the cured product after moisture curing.

[0094] The following examples are provided for more detailed explanation. It should be noted that these examples are merely illustrative and should not be construed as limiting. Unless otherwise specified, "parts" in each example refer to parts by mass, and "%" refers to % by mass.

[0095] Synthesis Example 1 70 parts of methyl methacrylate, 30 parts of 2-ethylhexyl methacrylate, 8 parts of 3-methacryloxypropyltrimethoxysilane, 0.1 parts of titanocene dichloride as a metal catalyst, and 40 parts of ethyl acetate as an organic solvent were placed in a reaction vessel and heated to 80°C under a nitrogen atmosphere with stirring. Next, 3.4 parts of mercaptoethanol were added, and the reaction was carried out for 16 hours while adjusting the temperature by heating and / or cooling so that the temperature inside the reaction vessel could be maintained at 80°C. After the 16-hour reaction, the temperature of the reactant was returned to room temperature (23°C), and the polymerization was terminated, yielding a solution of a crosslinkable silicon group-containing (meth)acrylic polymer (a1) having hydroxyl groups (non-volatile content 66% by mass). The number average molecular weight of the crosslinkable silicon group-containing (meth)acrylic polymer (a1) having hydroxyl groups, as measured by gel permeation chromatography (GPC), was 4,755.

[0096] Synthesis Example 2 100 parts of polypropylene glycol ethylene oxide adduct (Mitsui Chemicals SKC, "EDL-S101" (number average molecular weight 7,000)), 84.7 parts of adipic acid / 1,6-hexanediol-based crystalline aliphatic polyester polyol (Toyokuni Oil Mills, "HS2H-201AP" (number average molecular weight 2,000)), and 31.9 parts of adipic acid / 1,6-hexanediol-based crystalline aliphatic polyester polyol (Toyokuni Oil Mills, "HS2H-451A" (number average molecular weight 4,500)) were melt-mixed at 100 ° C. for 1 hour and then dehydrated under reduced pressure to obtain a polyol mixture. To the obtained polyol mixture, 23.9 parts of diphenylmethane diisocyanate (MDI) (Tosoh Corporation, "Millionate MT") were added, and the mixture was allowed to react for 3 hours at 100 ° C. with stirring under a nitrogen atmosphere to obtain a urethane prepolymer (a2). To the resulting urethane prepolymer (a2), 64.7 parts (solids content equivalent) of the crosslinkable silicon group-containing (meth)acrylic polymer (a1) obtained in Synthesis Example 1 and 13.3 parts of N-phenyl-3-aminopropyltrimethoxysilane (a3) ​​(manufactured by Shin-Etsu Chemical Co., Ltd., "KBMB573" (anilinosilane)) were added, and the mixture was stirred at 100°C for 2 hours, allowing the reaction to proceed until the -NCO absorption derived from the isocyanate group disappeared in IR spectrum measurement. After completion of the reaction, the solvent was distilled off to obtain a crosslinkable silicon group-containing polymer (Polymer A).

[0097] Synthesis Example 3 A flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser was charged with 70 parts of methyl methacrylate, 30 parts of 2-ethylhexyl methacrylate, 12 parts of γ-methacryloxypropyltrimethoxysilane, 0.1 parts of titanocene dichloride as a metal catalyst, and 40 parts of ethyl acetate as an organic solvent. The contents of the flask were heated to 80°C and stirred while introducing nitrogen gas into the flask. Next, 8.5 parts of 3-mercaptopropyltrimethoxysilane, which had been thoroughly purged with nitrogen gas, was added all at once to the stirred flask, and the contents of the flask were heated and cooled while stirring, maintaining the temperature at 80°C for 16 hours. After the reaction, the temperature of the reactant was returned to room temperature (23°C) to terminate the polymerization, yielding an ethyl acetate solution of a crosslinkable silicon group-containing (meth)acrylic polymer (polymer B) having two silyl groups per molecule. The residual monomer rate of the ethyl acetate solution of polymer B was measured using gas chromatography (GPC) to determine the polymerization rate, which was 97%. The viscosity of the ethyl acetate solution of polymer B at 25° C. was 2.2 (Pa s), and the solid content was 70.5% when heated to 105° C. The molecular weight of the obtained polymer B measured by gel permeation chromatography (GPC) was weight average molecular weight (Mw) = 3800, number average molecular weight (Mn) = 1500, and dispersion index = 2.4.

[0098] Synthesis Example 4 25 parts of polypropylene glycol (AGC Corporation, "EXCENOL 2020" (hydroxyl group count: 2, Mn: 2,000), 25 parts of adipic acid / 1,6-hexanediol-based crystalline aliphatic polyester polyol (Toyokuni Oil Mills, Ltd., "HS2H-451A" (number average molecular weight: 4,500)), and 50 parts of aromatic amorphous polyester polyol (Toyokuni Oil Mills, Ltd., number average molecular weight: 2,000) were melt-mixed at 100°C for 1 hour and then dehydrated under reduced pressure to obtain a polyol mixture. 21.0 parts of diphenylmethane diisocyanate (MDI) (Tosoh Corporation, "Millionate MT") was added to the obtained polyol mixture, and the mixture was allowed to react at 100°C for 3 hours with stirring under a nitrogen atmosphere to obtain a urethane prepolymer (Polymer C).

[0099] [Measurement Methods] In Synthesis Examples 1, 2, and 3, the number average molecular weight and IR spectrum were measured as follows.

[0100] <Number Average Molecular Weight> The measurement object was measured by gel permeation chromatography (GPC) under the following measurement conditions, and the number average molecular weight was determined as the molecular weight of the highest frequency converted to standard polyethylene glycol using polystyrene as the standard substance. Measurement device: Gel permeation chromatograph analyzer (manufactured by Tosoh Corporation, "HLC-8220") Columns used: One G7000HXL (manufactured by Tosoh Corporation), two GMHXL (manufactured by Tosoh Corporation), and one G2000HXL (manufactured by Tosoh Corporation) Solvent: Tetrahydrofuran Flow rate: 1.0 ml / min Measurement temperature: 40°C

[0101] <IR spectrum> Measurement device: FT-IR measurement device (manufactured by JASCO Corporation, "FT-IR460Plus")

[0102] [Production Example 1] Polymer A obtained in Synthesis Example 2, Polymer B obtained in Synthesis Example 3, Resin A, Resin B, a moisture absorbent, a silane-based adhesion promoter, and a crosslinking catalyst were mixed in the blending ratio (solid content: parts by mass) shown in Table 1, and the mixture was stirred and mixed in an environment of 120°C. Finally, the mixture was degassed under reduced pressure to produce moisture-curable adhesive A-1, which was solid at room temperature (23°C).

[0103] [Production Examples 2, 3, 4, and 5] Moisture-curing adhesives A-2, A-3, A-4, A-5, and A-6 that are solid at room temperature (23°C) and adhesive A'-1 that is liquid at room temperature (23°C) were produced in the same manner as in Production Example 1, except that the components shown in Table 1 were mixed in the blending ratio (solid content: parts by mass) shown in Table 1.

[0104]

[0105] The components shown in Table 1 are as follows: Polymer A: crosslinkable silicon group-containing polymer obtained in Synthesis Example 2. Polymer B: crosslinkable silicon group-containing (meth)acrylic polymer having two silyl groups per molecule obtained in Synthesis Example 3. Polymer C: urethane prepolymer obtained in Synthesis Example 4. Resin A: styrene resin (manufactured by Yasuhara Chemical Co., Ltd., "YS Resin SX100"). Resin B: modified silicone resin (manufactured by Kaneka Corporation, "SAX220"). Moisture absorbent: vinyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM1003"). Adhesion impartant: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM603"). Crosslinking catalyst: dioctyl tin compound (manufactured by Nitto Kasei Co., Ltd., "Neostan U-830"). Adhesive A: moisture-curing adhesive (manufactured by Cemedine Co., Ltd., "Super XG No. 777")

[0106] The 120 ° C. viscosity (Pa s) in Table 1 was measured by the following method. Moisture-curing adhesives A-1, A-2, A-3, A-4, A-5, and A-6, which are solid at room temperature (23 ° C.), were each heated to 120 ° C. and melted, and the viscosity was measured using a cone-plate viscometer CV-1 (manufactured by Toa Kogyo Co., Ltd., cone diameter: 14.5 mm, cone angle: 2.0 °, rotation speed: 20 rpm). Note that adhesive A used in Production Example 7 in Table 1 is a liquid at room temperature (23 ° C.), so the 120 ° C. viscosity was not measured, and the viscosity at room temperature (23 ° C.) is listed in Table 1.

[0107] Example 1 A composition for a balance weight was prepared by mixing 100 parts of the moisture-curing adhesive A-1 obtained in Production Example 1 as the moisture-curing adhesive (A), 250 parts of tungsten powder B as the tungsten-based powder (B), and tungsten powder B, followed by stirring in an environment of 120°C and degassing under reduced pressure.

[0108] [Examples 2 to 18, Comparative Example 1] Compositions for balance weights were prepared in the same manner as in Example 1, except that the moisture-curing adhesive (A) and the tungsten-based powder (B) shown in Tables 2 to 4 were used, respectively.

[0109] Comparative Example 2 A composition for balance weights was prepared in the same manner as in Example 1, except that moisture-curing adhesive A'-1, which is liquid at room temperature (23°C), was used as the moisture-curing adhesive (A).

[0110] The components used in Examples 2 to 17 and Comparative Examples 1 and 2 are as follows. Moisture-curing adhesive A-1: ​​Moisture-curing adhesive A-1 that is solid at room temperature (23 ° C) as shown in Table 1. Moisture-curing adhesive A-2: Moisture-curing adhesive A-2 that is solid at room temperature (23 ° C) as shown in Table 1. Moisture-curing adhesive A-3: Moisture-curing adhesive A-3 that is solid at room temperature (23 ° C) as shown in Table 1. Moisture-curing adhesive A-4: Moisture-curing adhesive A-4 that is solid at room temperature (23 ° C) as shown in Table 1. Moisture-curing adhesive A-5: Moisture-curing adhesive A-5 that is solid at room temperature (23 ° C) as shown in Table 1. Moisture-curing adhesive A-6: Moisture-curing adhesive A-6 that is solid at room temperature (23 ° C) as shown in Table 1. Moisture-curing adhesive A'-1: Moisture-curing adhesive that is liquid at room temperature (23 ° C) (manufactured by Cemedine Co., Ltd., product name "Super XG No. 777" (viscosity: 85.0 Pa s / 23 ° C)). Tungsten powder A: tungsten powder (manufactured by Nippon New Metals Co., Ltd., trade name "W-6" (particle size 8.0 to 16.0 μm; specific gravity 19.3)) Tungsten powder B: tungsten powder (manufactured by Nippon New Metals Co., Ltd., trade name "W-L" (particle size 10.0 to 40.0 μm; specific gravity 19.3)) Tungsten powder C: tungsten powder (manufactured by A.L.M.T. Corporation, trade name "D100" (particle size 7.6 to 12.0 μm; specific gravity 19.3)) Tungsten powder D: tungsten powder (manufactured by A.L.M.T. Corporation, trade name "coarse grain" (particle size 23.0 to 28.0 μm; specific gravity 19.3)) Tungsten powder E: tungsten powder (manufactured by A.L.M.T. Corporation, trade name "W-U250" (particle size 23.0 to 28.0 μm; specific gravity 19.3))

[0111] [Physical Properties and Tests] <Specific Gravity> The balance weight composition obtained in Example 1 was heated and melted at 120°C, applied to a peelable surface, and cured to prepare a sheet measuring 1 cm x 1 cm x 1 mm. The prepared sheet was aged at 23°C and 50% RH for one week, and then its specific gravity was measured by the underwater displacement method in accordance with JIS K7112. The results are also shown in Table 2. Similarly, sheets were prepared using the balance weight compositions obtained in Examples 2 to 18 and Comparative Examples 1 and 2, and the specific gravity of each was measured. The results are also shown in Tables 2 to 4.

[0112] <Shear Adhesion Strength After 5 Minutes> The balance weight composition obtained in Example 1 was heated and melted at 120°C and applied to a first aluminum plate (25 mm x 75 mm x 2 mm) whose application surface had been degreased with acetone to a thickness of 100 µm. Immediately after application, a second aluminum plate (25 mm x 75 mm x 2 mm) whose adhesive surface had been degreased with acetone was attached to the applied surface so that the overlapping area measured 25 mm x 2 mm from one edge, thereby preparing a test specimen. The test specimen was cured for 5 minutes in an environment of 23°C and 50% RH, and then measured for shear adhesive strength after 5 minutes (5-minute rising shear adhesive strength) (N / mm) at a tensile speed of 50 mm / min in accordance with JIS K6850. ２ The results are also shown in Table 2. Similarly, test specimens were prepared using the balance weight compositions obtained in Examples 2 to 18 and Comparative Examples 1 and 2, and the shear bond strength (N / mm ２ The results are shown in Tables 2 to 4.

[0113] <Extrudability> An extrudability test was carried out using an air pulse dispenser "ML-808FX" manufactured by Musashi Engineering Co., Ltd., a tabletop coating robot "SHOTMASTER 300DS" manufactured by Musashi Engineering Co., Ltd., and a metal needle "SNA19G-B" manufactured by Musashi Engineering Co., Ltd. The coating conditions were a coating pressure of 200 kPa for 10 seconds, and the discharge amount when extruded was measured.

[0114] [Evaluation] The balance weight compositions obtained in Examples 1 to 18 and Comparative Examples 1 and 2 were evaluated as follows.

[0115] <Automation Characteristics> In the extrusion test, when the extrusion extrusion rate was 15 mg / 10 seconds or more, it was rated as A (pass), and when it was less than 15 mg / 10 seconds, it was rated as D (fail). The evaluation results are shown in Tables 2 to 5.

[0116] <Drip and slippage prevention properties> In the 5-minute shear bond strength test, if the strength was 0.2 MPa or more, it was rated as A (pass), and if it was less than 0.2 MPa, it was rated as D (fail). The evaluation results are shown in Tables 2 to 5.

[0117]

[0118]

[0119]

[0120] It is clear from Tables 2 to 4 that the balance weight compositions according to the examples exhibit good extrudability and have excellent automation characteristics for automating the application of the balance weight composition. This shows that automatic application of the balance weight composition makes it possible to easily perform dynamic balancing of the rotating body, improving workability.

[0121] It is clear from Tables 2 to 4 that the balance weight compositions according to the examples exhibit good automation properties, and that the automation properties of the application of the balance weight compositions are excellent. This means that when applying the balance weight composition automatically, it is possible to precisely apply an appropriate amount, which makes it easy to adjust the balance by dynamic balancing of the rotating body, improving workability.

[0122] Tables 2 to 4 confirm that the compositions for balance weights according to the examples exhibit good shear bond strength after 5 minutes (initial shear bond strength after 5 minutes), have a fast solidification rate (excellent fast curing and fast adhesion), and are excellent in preventing dripping and slippage. This shows that even when the balance is measured immediately after application, dripping and slippage of the composition for balance weights can be prevented, making it possible to proceed to the next process and improving workability.

[0123] On the other hand, Tables 2 to 4 show that the balance weight composition having a specific gravity of 9.0 according to Comparative Example 1 had excellent 5-minute shear bond strength but poor extrusion resistance and poor automation characteristics. Furthermore, the balance weight composition according to Comparative Example 2, which uses a moisture-curing adhesive that is liquid at room temperature (23°C), had a high viscosity at 23°C, and when heated, moisture curing progressed, making application difficult. Therefore, when applied at 23°C, the composition exhibited low 5-minute shear bond strength, extrusion resistance, and automation characteristics, and was confirmed to have poor fast-curing, fast-adhesion, automation characteristics, and drip / slip prevention characteristics. Therefore, with a balance weight composition using a moisture-curing adhesive that is liquid at room temperature (23°C), it is difficult to measure the balance immediately after application, and there is a high possibility that the applied balance weight will drip or slip when proceeding to the next process.

Claims

1. A composition for balance weights, which is solid at room temperature and has a specific gravity of 8.5 or less, and which comprises: (A) a moisture-curing adhesive that is solid at room temperature; and (B) a tungsten-based powder.

2. The composition for balance weights according to claim 1, wherein the moisture-curing adhesive (A) that is solid at room temperature is composed primarily of an isocyanate group-containing urethane prepolymer or a crosslinkable silicon group-containing polymer.

3. The balance weight composition according to claim 1, wherein the moisture-curing adhesive (A) that is solid at room temperature has a viscosity of 50 Pa·s or less at 120°C, and the tungsten-based powder (B) has a particle size in the range of 0.1 to 200 μm.

4. A balance weight in which the composition for balance weights according to any one of claims 1 to 3 is applied to a required portion of a rotating body in order to adjust the balance of the rotating body.

5. A method for applying the composition for balance weights according to any one of claims 1 to 3 to an application site of a rotating body for adjusting balance.

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