Curable composition and its cured product and molded product

Abstract

To provide a novel curable composition containing a magnetic powder and a cured product of the same.SOLUTION: There are provided a curable composition and a cured product of the same. The curable composition comprises a urethane prepolymer having an isocyanate group as the terminal group and a magnetic powder.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a curable composition, a cured product thereof, and a molded article. [Background technology]

[0002] Resin compositions containing magnetic powder are easy to mold, and thus molded products thereof are used as magnetic parts in a variety of fields. As a resin composition containing magnetic powder, for example, a thermoplastic elastomer composition containing a thermoplastic elastomer and magnetic powder has been disclosed (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 255218 Summary of the Invention [Problem to be solved by the invention]

[0004] A primary object of the present disclosure is to provide a novel curable composition containing magnetic powder and a cured product thereof. [Means for solving the problem]

[0005] The present disclosure provides a curable composition according to [1], a cured product of the curable composition according to [2], and a molded product according to [3]. [1] A urethane prepolymer having an isocyanate group as a terminal group; Magnetic powder; A curable composition comprising: [2] A cured product of the curable composition according to [1]. [3] A molded article comprising a cured product of the curable composition according to [2]. [Effects of the Invention]

[0006] The present disclosure provides a novel curable composition containing a magnetic powder and a cured product thereof. The present disclosure also provides a molded article containing the cured product of such a curable composition. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present disclosure will be described. However, the present disclosure is not limited to the following embodiments. In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In addition, in numerical ranges described in stages in this specification, the upper or lower limit of a numerical range of a certain stage may be replaced with the upper or lower limit of a numerical range of another stage. In addition, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in an example.

[0008] As used herein, the term "polyol" refers to a compound having an average of more than one (for example, two or more) hydroxyl groups in the molecule.

[0009] As used herein, the term "polyisocyanate" refers to a compound having an average of more than one (for example, two or more) isocyanate group in the molecule.

[0010] Unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more.

[0011] [Curable composition] The curable composition of one embodiment contains a urethane prepolymer having an isocyanate group as a terminal group (hereinafter, sometimes referred to as "component (A)") and a magnetic powder (hereinafter, sometimes referred to as "component (B)").

[0012] Component (A): a urethane prepolymer having an isocyanate group as a terminal group Component (A) may be a reaction product of a polyol (hereinafter sometimes referred to as "component (A1)") and a polyisocyanate (hereinafter sometimes referred to as "component (A2)"). That is, component (A) may have a polymer chain containing structural units derived from component (A1) and structural units derived from component (A2), and an isocyanate group bonded to the end of the polymer chain. Because component (A) has an isocyanate group as a terminal group, it reacts with moisture (in the air or on the surface of an adherend) to undergo polymerization or crosslinking, and a cured product of the curable composition may be formed.

[0013] Component (A) can be obtained by reacting component (A1) with component (A2). The content of the structural units derived from component (A1) and the content of the structural units derived from component (A2) in component (A) correspond to the amounts of component (A1) and component (A2) charged to provide the respective structural units, and the content of the structural units can be adjusted by adjusting these charged amounts. Furthermore, since urethane bonds are formed by the reaction of component (A1) with component (A2), the polymer chain in component (A) can contain urethane bonds. Furthermore, by increasing the equivalent ratio of isocyanate groups in component (A2) to hydroxyl groups in component (A1), isocyanate groups can be introduced at the end of the polymer chain. Component (A) can be obtained by isolating the reaction product of component (A1) and component (A2), or by using the reaction product in the reaction system directly without isolation.

[0014] Examples of the component (A1) include polyester polyols, polyether polyols, polyether ester polyols, polyurethane polyols, polycarbonate polyols, and polyolefin polyols.

[0015] Component (A1) may include, for example, a polyester polyol, which may be a polycondensation reaction product of a polyhydric alcohol and a polycarboxylic acid, or a polycondensation reaction product of a dihydric alcohol and a dicarboxylic acid.

[0016] Examples of polyhydric alcohols include aliphatic dihydric alcohols in which some carbon atoms (-CH- (methylene groups)) may be substituted with oxygen atoms (-O-), such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, isomers of butanediol, isomers of pentanediol, isomers of hexanediol, 2,2-dimethyl-1,3-propanediol, 2-methylpropanediol, 2,4,4-trimethyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; alicyclic dihydric alcohols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol; and dihydric alcohols (dihydric alcohols having an aromatic ring) such as 4,4'-dihydroxydiphenylpropane, bisphenol A, bisphenol F, pyrocatechol, resorcinol, and hydroquinone.

[0017] Examples of polycarboxylic acids include aromatic polycarboxylic acids (polycarboxylic acids having an aromatic ring) such as phthalic acid, isophthalic acid, terephthalic acid, and 1,2,4-benzenetricarboxylic acid; aliphatic polycarboxylic acids such as maleic acid, fumaric acid, aconitic acid, 1,2,3-propanetricarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, and sebacic acid; and alicyclic polycarboxylic acids such as cyclohexane-1,2-dicarboxylic acid and 1,4-cyclohexanediene-1,2-dicarboxylic acid. Instead of polycarboxylic acids, polycarboxylic acid derivatives such as carboxylic acid anhydrides and compounds in which some of the carboxyl groups are esterified can also be used.

[0018] Component (A1) may contain, for example, a polyether polyol, such as polyethylene glycol (PEG), polypropylene glycol (PPG), ethylene oxide / propylene oxide copolymer, polytetramethylene ether glycol (PTMEG), or sorbitol-based polyol.

[0019] Examples of component (A2) include aromatic polyisocyanates in which an isocyanate group is bonded to an aromatic hydrocarbon, aliphatic polyisocyanates in which an isocyanate group is bonded to an aliphatic hydrocarbon, and alicyclic polyisocyanates in which an isocyanate group is bonded to an alicyclic hydrocarbon. Component (A2) may be a polymer of aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, or the like.

[0020] Examples of aromatic polyisocyanates include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 2,4'- or 4,4'-diphenylmethane diisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4',4''-triphenylmethane triisocyanate, m- or p-isocyanatophenylsulfonyl isocyanate, m- or p-xylylene diisocyanate, and α,α,α',α'-tetramethylxylylene diisocyanate.

[0021] Examples of aliphatic polyisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl)fumarate, bis(2-isocyanatoethyl)carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate.

[0022] Examples of alicyclic polyisocyanates include isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexene-1,2-dicarboxylate, and 2,5- or 2,6-norbornane diisocyanate.

[0023] When the component (A1) and the component (A2) are reacted to obtain the component (A), a catalyst for forming a urethane prepolymer (hereinafter sometimes referred to as the "component (A3)") may be used as needed. The component (A3) can be a known catalyst that promotes a urethanization reaction or a urea reaction.

[0024] The content of the component (A3) can be adjusted appropriately depending on the types of the components (A1) and (A2), etc. The content of the component (A3) may be, for example, 0.001 to 5 mass%, 0.005 to 1 mass%, or 0.01 to 0.1 mass%, based on the total amount of the components (A1) and (A2).

[0025] Component (A) can be obtained by reacting components (A1) and (A2) in the presence or absence of component (A3). The temperature and time for reacting components (A1) and (A2) are not particularly limited, but may be, for example, 70 to 130°C and 30 minutes to 48 hours.

[0026] The content of the component (A) (total of the components (A1), (A2), and (A3)), based on the total amount of the curable composition, may be 1 mass % or more, 5 mass % or more, 10 mass % or more, 15 mass % or more, or 20 mass % or more, and may be 90 mass % or less, 80 mass % or less, 70 mass % or less, 60 mass % or less, 50 mass % or less, or 40 mass % or less.

[0027] (B) Component: Magnetic powder There are no particular restrictions on component (B) as long as it is a magnetic powder, and it may be either a soft magnetic powder or a hard magnetic powder. The metal of component (B) may be, for example, at least one metal selected from the group consisting of pure iron, Fe-Si alloys, Fe-Si-Al alloys (Sendust), Fe-Ni alloys (Permalloy), Fe-Cu-Ni alloys (Permalloy), Fe-Co alloys (Permendur), Fe-Cr alloys (stainless steel), Fe-Ni-Cr alloys (stainless steel), Fe-Cr-Si alloys (electromagnetic stainless steel), Fe-Ni-Mn-C alloys (Invar), Sm-Co alloys (rare earth magnets), Nd-Fe-B alloys (rare earth magnets), Sm-Fe-N alloys (rare earth magnets), Al-Ni-Co alloys (Alnico magnets), Ni-Zn alloys (ferrites), Ni-Zn-Cu alloys (ferrites), Mn-Zn alloys (ferrites), and salts containing iron oxides. The metal powder that is the soft magnetic powder may be amorphous. The soft magnetic metal powder may be an Fe amorphous alloy. The soft magnetic metal powder may be at least one of amorphous iron powder and carbonyl iron powder. Furthermore, component (B) may contain multiple metal elements. For example, the metal powder may further contain at least one element selected from the group consisting of base metal elements, noble metal elements, transition metal elements, and rare earth elements in addition to the above elements. The metal powder may further contain at least one element selected from the group consisting of copper (Cu), titanium (Ti), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), tin (Sn), chromium (Cr), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), oxygen (O), beryllium (Be), phosphorus (P), boron (B), and silicon (Si).

[0028] The average particle size of component (B) may be 1 μm or more or 3 μm or more, and may be 200 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. Here, the average particle size refers to the median diameter (D50) in the volume-based particle size distribution. The average particle size of component (B) can be measured, for example, by laser diffraction scattering.

[0029] The content of the (B) component may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, or 60% by mass or more, and may be 99% by mass or less, 95% by mass or less, 90% by mass or less, 85% by mass or less, or 80% by mass or less, based on the total amount of the curable composition.

[0030] The curable composition may further contain other components as needed. Examples of other components include a curing catalyst (a catalyst for promoting the reaction of component (A) with moisture), a coupling agent, an antifoaming agent, a nucleating agent, a plasticizer, a surfactant, a flame retardant, a filler, a photocoloring agent, a thermal color-developing inhibitor, an imaging agent, a thermal crosslinking agent, an ultraviolet absorber, a light stabilizer, a dehydrating agent, an antiaging agent, an antioxidant, an antistatic agent, an adhesion promoter, a dispersant, a solvent, a pigment, a dye, a fragrance, and carbon black. The content of the other components may be 0.001% by mass or more, 0.01% by mass or more, 0.1% by mass or more, or 1% by mass or more, and 50% by mass or less, 30% by mass or less, 10% by mass or less, or 5% by mass or less, based on the total amount of the curable composition.

[0031] The method for preparing the curable composition is not particularly limited as long as it results in a desired curable composition. The curable composition can be obtained, for example, by a production method including the steps of reacting the (A1) component with the (A2) component to synthesize the (A) component, and mixing the synthesized (A) component with the (B) component to obtain the curable composition. The curable composition can also be obtained, for example, by a production method including the steps of mixing the (A1) component with the (B) component to obtain a mixture, and adding the (A2) component to the obtained mixture and reacting it with the (A1) component to synthesize the (A) component. The (A3) component and other components can be added at any stage, as needed.

[0032] The temperature and time for reacting the components (A1) and (A2) when synthesizing the component (A) are not particularly limited, but may be, for example, 70 to 140°C and 30 minutes to 48 hours.

[0033] [Cured product of curable composition] The cured product of one embodiment is a cured product of a curable composition. The curable composition can be cured, for example, by curing the curable composition, because the isocyanate group of component (A) reacts with moisture (moisture in the air or on the surface of an adherend). The conditions for curing the curable composition (curing conditions) may be, for example, 10 to 35°C and 30 to 60% RH (relative humidity) for 1 to 10 days. In this way, a cured product of the curable composition can be obtained. The curable composition has the advantage that a cured product can be obtained at such a low temperature and in a short period of time, and further, no heating device or light irradiation device is required for curing.

[0034] The cured product of the curable composition contains a urethane polymer having urethane bonds formed by the reaction of component (A) with moisture in the air to increase the molecular weight. The urethane polymer may further contain biuret bonds, allophanate bonds, etc. formed by further reaction of urea bonds with isocyanate groups. The cured product of the curable composition containing such a urethane polymer has excellent properties such as flexibility, stretchability, and bending properties, and can be molded into any shape.

[0035] [Molded product] The molded product of one embodiment is obtained by curing a curable composition and includes a cured product of the curable composition. The shape of the molded product containing the cured product is not particularly limited and may include, for example, a film (membrane), a plate, a powder, or a granule, and may be any shape depending on the application. The shape of the molded product containing the cured product may be, for example, a continuous shape or a discontinuous shape. Here, a continuous shape means a shape that is continuous in at least one direction. Examples of continuous shapes include a linear shape, a curved shape, and a planar shape. A discontinuous shape means a shape that is not continuous in one direction and is interrupted. Examples of discontinuous shapes include a dot shape, a spot shape, and a dashed line shape.

[0036] Examples of methods for obtaining a molded product from a curable composition include a method including a step of melting the curable composition and applying it to form a composition of any shape (composition film, composition layer, etc.), and a step of curing the composition of any shape (composition film, composition layer, etc.) to obtain a cured product of any shape (cured product film, cured product layer, etc.).

[0037] The temperature at which the curable composition is melted may be, for example, 60 to 130°C.

[0038] The application method is not particularly limited, and examples thereof include methods using an application device such as a bar coater, a die coater, a roll coater, a sprayer, a dispenser, etc. The application pattern of the curable composition can be arbitrarily set according to the desired shape.

[0039] The method of curing a composition (composition film, composition layer, etc.) to obtain a cured product (cured product film, cured product layer, etc.) may be the same as the conditions (curing conditions) for curing the above-mentioned curable composition.

[0040] A cured product of the curable composition tends to have excellent flexibility, stretchability, bending properties, etc., and can therefore be molded into a three-dimensional shape by bending the cured product of the curable composition, etc. Therefore, a molded product can also be obtained by a method including, for example, a step of obtaining a first molded product in the shape of a film (membrane), a plate, or the like, and a step of further molding the first molded product to obtain a second molded product.

[0041] The molded article can be suitably used as a magnetic part. If necessary, the molded article may be magnetized by applying an external magnetic field. [Example]

[0042] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0043] Example 1 [Preparation of Curable Composition and Evaluation of Cured Film] <Preparation of Curable Composition> After dispersing 70 parts by mass of the (B) component (B-1) in 27 parts by mass of the (A1) component (A1-1), the mixture was heated to 110°C and vacuum dehydrated for 30 to 60 minutes while stirring. Then, 3 parts by mass of the (A2) component (A2-1) was added and mixed to homogeneity. The resulting mixture was then reacted at 110°C for 1 hour, and further degassed and stirred under reduced pressure at 110°C for 1 hour to obtain the curable composition of Example 1. Table 1 shows the blending composition (parts by mass) of each component. The curable composition is presumed to contain component (A) (urethane prepolymer), which is a reaction product of component (A1) and component (A2), and component (B).

[0044] Component (A1): Polyol A1-1: Polyester polyol (number of hydroxyl groups: 2, number average molecular weight: 5000) of dihydric alcohol (1,4-butanediol and neopentyl glycol) and dicarboxylic acid (adipic acid) Component (A2): Polyisocyanate A2-1: Diphenylmethane diisocyanate (manufactured by Tosoh Corporation, product name: Millionate MT, number of isocyanate groups: 2) (B) Component: Magnetic powder B-1: Nd-Fe-B alloy (manufactured by Magnequench, product name: MQFP-14-12, D50: 25 μm)

[0045] <Evaluation of cured film> (Preparation of cured film) The curable composition was melted at 100°C to form a film with a thickness of 100 µm, which was then aged in a thermo-hygrostat at a temperature of 23°C and a humidity of 50% for 7 days to obtain a cured film containing a cured product of the curable composition.

[0046] (glass transition temperature) Measurements were performed using a differential scanning calorimeter (Shimadzu Corporation, product name: DSC-60A Plus). Approximately 10 mg of the cured film was cut out and placed in an aluminum cell, which was then capped with an aluminum lid. Measurements were performed by scanning the temperature range from -125°C to 120°C at a rate of 5°C / min, and the temperature at which the baseline shifted was taken as the glass transition temperature. The results are shown in Table 1.

[0047] (tensile modulus, breaking strength, and breaking elongation) The cured film was punched out with a No. 1 dumbbell to prepare test specimens, and the tensile modulus (MPa), breaking strength (MPa), and breaking elongation (%) of the test specimens were measured at a pulling rate of 200 mm / min using an Autograph AGS-X (Shimadzu Corporation). The results are shown in Table 1.

[0048] (90° bending test) A 90° bending test was performed on cured film at 23°C. In the 90° bending test, a rectangular piece of cured film (length: 60 mm, width: 5 mm) was cut and fixed near the center, and one end of the longitudinal direction was lifted perpendicular to the center fixed part. After 60 seconds of standing, the lifted end was returned to its original position, and the condition of the bent center fixed part was observed. If no change in the state of the center fixed part after bending was observed compared to before bending, the test piece was deemed to have bending resistance and rated as "A." On the other hand, if a change in state was observed in the center fixed part after bending, such as breakage or cracking, compared to before bending, the test piece was rated as "B." The results are shown in Table 1.

[0049] [Table 1]

Claims

1. a urethane prepolymer having an isocyanate group as a terminal group; Magnetic powder; A curable composition comprising:

2. A cured product of the curable composition according to claim 1.

3. A molded article comprising a cured product of the curable composition according to claim 2.

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