JP7735214B2 - Two-component curing polyurethane resin composition - Google Patents

Description

The present invention relates to a two-component curing polyurethane resin composition and electrical and electronic components using the same.

Conventionally, electronic circuit boards and electronic components have been encapsulated using polyurethane resin compositions to protect them from external factors. The raw materials for such polyurethane resin compositions are generally derived from petroleum. From the perspective of considering environmental issues such as global warming, it is desirable to use raw materials derived from biomass, such as plants.

As an example of a biomass-derived raw material, Patent Document 1 discloses the use of a polyfarnesene polyol compound together with a castor oil-based polyol compound as a polyol compound.

Patent No. 6678903

The inventors' research has revealed that when farnesene polyol and castor oil-based polyol are used as polyols, although the resulting composition has excellent low dielectric properties, it does not provide sufficient hardness.

In view of the above, an embodiment of the present invention aims to provide a two-component curing polyurethane resin composition that uses biomass-derived raw materials and achieves both low dielectric properties and hardness.

The present invention includes the embodiments shown below.
[1] A two-component curable polyurethane resin composition comprising a first component containing a polyol and a second component containing a polyisocyanate, wherein the polyol contains a cardanol polyol and a farnesene polyol.
[2] The two-component curing polyurethane resin composition according to [1], wherein the mass ratio of the cardanol polyol to the farnesene polyol is 10:90 to 80:20.
[3] The two-component curing polyurethane resin composition according to [1] or [2], wherein the cardanol polyol is a novolac cardanol polyol.
[4] The two-component curing polyurethane resin composition according to any one of [1] to [3], wherein the farnesene polyol is a polyfarnesene diol.
[5] The two-component curing polyurethane resin composition according to any one of [1] to [4], wherein the polyisocyanate includes 1,5-pentamethylene diisocyanate and/or a derivative thereof.
[6] The two-component curing polyurethane resin composition according to any one of [1] to [5], wherein the cured product has a biomass content of 60% or more.
[7] The two-component curing polyurethane resin composition according to any one of [1] to [6], which is used for sealing electric and electronic components.
[8] An electric/electronic part resin-sealed with the two-component curing polyurethane resin composition according to any one of [1] to [7] above.

According to an embodiment of the present invention, it is possible to achieve both low dielectric properties and hardness while using raw materials derived from biomass.

The two-component curing polyurethane resin composition according to this embodiment is a polyurethane resin composition having a first component containing a polyol (A) and a second component containing a polyisocyanate (B), wherein the polyol (A) contains a cardanol polyol (A1) and a farnesene polyol (A2).

<First Component>
[Cardanol polyol (A1)]
Cardanol polyol (A1) is used as the polyol (A) contained in the first component. Cardanol polyol (A1) is a cardanol-derived polyol synthesized from cardanol. Cardanol is a major component of cashew nut shell liquid (hereinafter referred to as CNSL), and is a compound in which a hydroxy group and a linear hydrocarbon group having 15 carbon atoms are bonded to a benzene ring. CNSL is an oily component contained in cashew nut shells. Natural CNSL is mainly composed of anacardic acid, and heat treatment after oil extraction decarboxylates the anacardic acid to form cardanol.

Novolac cardanol polyol is preferably used as the cardanol polyol (A1). Novolac cardanol polyol is a polyol obtained by condensing cardanol with an aldehyde compound such as formaldehyde, and then adding an epoxy compound such as ethylene oxide to the resulting condensate. As the novolac cardanol polyol, one represented by the following formula (1) can be used.

In formula (1), R ¹ represents a linear hydrocarbon group having 15 carbon atoms, and may be a saturated or unsaturated hydrocarbon group. Specific examples of R ¹ include -(CH ₂ ) ₁₄ CH ₃ , -(CH ₂ ) ₆ CH═CH(CH ₂ ) ₆ CH ₃ , -(CH ₂ ) ₆ CH═CHCH ₂ CH═CH(CH ₂ ) ₃ CH ₃ , and -(CH ₂ ) ₆ CH═CHCH ₂ CH═CH(CH ₂ ) ₂ CH═CH _2. Multiple R ^1s contained in one molecule may be the same or different.

In formula (1), ^R2 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and more preferably a hydrogen atom. When multiple ^R2s are contained in one molecule, they may be the same or different.

In formula (1), ^R3 may be a hydrogen atom, a halogen atom, or a hydrocarbon group which may have a substituent. Examples of halogen atoms include a fluorine atom, a chlorine atom, and a bromine atom. Examples of hydrocarbon groups include an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group, and an aralkyl group. The hydrocarbon group preferably has 1 to 8 carbon atoms. Examples of the substituent include a halogen atom, a hydroxy group, and an alkoxy group. ^R3 is preferably a hydrogen atom or a methyl group. Multiple ^R3s contained in one molecule may be the same or different.

In formula (1), n represents a number of 0 or more. n is preferably 1 or more, and more preferably 1.5 or more. There is no particular upper limit for n, and it may be, for example, 50 or less, 20 or less, or 10 or less.

The hydroxyl value of the cardanol polyol (A1) is not particularly limited, but is preferably 80 to 250 mgKOH/g, more preferably 100 to 220 mgKOH/g, and may be 130 to 200 mgKOH/g. In this specification, the hydroxyl value (OHV) is measured in accordance with Method A of JIS K1557-1:2007.

The average functionality of the cardanol polyol (A1) (the number of hydroxy groups contained in one molecule) is 2.0 or more, preferably 2.2 to 8.0, more preferably 2.5 to 5.0, and may be 3.0 to 4.5.

In this specification, the average number of functional groups is a value calculated from the number average molecular weight (Mn) measured by GPC (gel permeation chromatography) in accordance with JIS K7252-1:2016 and the hydroxyl value (mgKOH/g) using the following formula:
Average functionality={(hydroxyl value)×(Mn)}/(56.11×1000)
Here, Mn is calculated from the elution time of the measurement sample using a calibration curve prepared from the molecular weight and elution time of standard polystyrene in the measurement by GPC method. The measurement conditions are, for example, a TSKgel Hx1 (Tosoh Corporation) column, THF (tetrahydrofuran) as the mobile phase, a mobile phase flow rate of 1.0 mL/min, a column temperature of 40°C, a sample injection volume of 50 μL, and a sample concentration of 0.2 mass%.

[Farnesene polyol (A2)]
The polyol (A) contained in the first component uses the cardanol polyol (A1) and a farnesene polyol (A2). The farnesene polyol (A2) is a farnesene-derived polyol synthesized from farnesene. Farnesene is a compound classified as a sesquiterpene and is a raw material derived from biomass obtained from plants. The farnesene may be α-farnesene, β-farnesene, or a combination of both.

As the farnesene polyol (A2), it is preferable to use a polyfarnesene diol. A polyfarnesene diol is a polymer obtained by polymerizing a farnesene-containing monomer, both ends of which are functionalized with hydroxy groups, and may be hydrogenated. The polymer may be a farnesene homopolymer or a copolymer of farnesene with another monomer. Examples of such other monomers include diene monomers other than farnesene and vinyl monomers. The content of the farnesene-derived structural units in the polymer is not particularly limited and may be, for example, 10 to 100% by mass, 30 to 100% by mass, 50 to 100% by mass, or 70 to 100% by mass. Preferably, the content of the farnesene-derived structural units is 100% by mass, i.e., a diol having hydroxy groups at both ends of a farnesene homopolymer.

In one embodiment, the polyfarnesene diol preferably used is a polymer obtained by anionic polymerization of β-farnesene, both ends of which are functionalized with hydroxy groups, or a hydrogenated version of such a polymer. In a preferred embodiment, a non-hydrogenated polyfarnesene diol made from a homopolymer of β-farnesene may be one represented by the following formula (2):

In formula (2), R ⁴ is a linking group that connects the farnesene polymer represented by [X] _p to OH, and examples thereof include alkanediyl groups having 1 to 8 carbon atoms (preferably 1 to 3 carbon atoms).

In formula (2), [X] is a structural unit derived from β-farnesene, and specific examples thereof include a 1,4-trans structural unit represented by the following formula (3), a 1,4-cis structural unit represented by formula (4), a 3,4-addition structural unit represented by formula (5), and a 1,2-addition structural unit represented by formula (6). Any one of these may be used alone, or two or more may be used in combination.

In one embodiment, [X] _p may be composed of 1,4-addition structural units represented by formula (3) or formula (4) and 3,4-addition structural units represented by formula (5). For example, the microstructure of the polyfarnesene diol may be composed of 40 to 80% by mass (more preferably 50 to 70% by mass) of 1,4-addition structural units and 20 to 60% by mass (more preferably 30 to 50% by mass) of 3,4-addition structural units. The contents of these structural units can be determined by ^1H NMR.

The hydroxyl value of the farnesene polyol (A2) is not particularly limited, but is preferably 10 to 100 mgKOH/g, more preferably 20 to 70 mgKOH/g, and may be 30 to 50 mgKOH/g.

[Polyol (A)]
The polyol (A) may be composed only of the cardanol polyol (A1) and the farnesene polyol (A2), or may further contain another polyol (A3) in addition to these. Preferably, from the viewpoint of increasing the biomass content, the polyol (A) is composed only of the cardanol polyol (A1) and the farnesene polyol (A2).

The other polyol (A3) is not particularly limited and may be a compound having multiple hydroxyl groups within the molecule, such as various polyols other than cardanol polyol (A1) and farnesene polyol (A2). Specific examples include polybutadiene polyol, castor oil-based polyol, polyether polyol, polyester polyol, polycarbonate polyol, dimer acid polyol, polycaprolactone polyol, acrylic polyol, polyisoprene polyol, and hydrogenated polyisoprene polyol. The other polyol (A3) may also be a low-molecular-weight polyol commonly used as a crosslinking agent, such as a polyhydric alcohol having a molecular weight of 300 or less. Specific examples include aromatic alcohols such as N,N-bis(2-hydroxypropyl)aniline, hydroquinone-bis(β-hydroxyethyl)ether, and resorcinol-bis(β-hydroxyethyl)ether, and aliphatic alcohols such as ethylene glycol, 1,4-butanediol, octanediol, trimethylolpropane, and triisopropanolamine.

In one embodiment, polybutadiene polyol may be used as the other polyol (A3). Polybutadiene polyol has a polybutadiene structure and at least two hydroxy groups in the molecule. The hydroxyl value of the polybutadiene polyol is not particularly limited and may be, for example, 10 to 200 mgKOH/g, 15 to 150 mgKOH/g, or 20 to 120 mgKOH/g.

The content of cardanol polyol (A1) in 100% by mass of polyol (A) is, for example, preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and may even be 40% by mass or more. Increasing the content of cardanol polyol (A1) can increase the hardness of the polyurethane resin after curing. The content of cardanol polyol (A1) is, for example, preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

The content of farnesene polyol (A2) in 100% by mass of polyol (A) is, for example, preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. By increasing the content of farnesene polyol (A2), low dielectric properties can be improved. The content of farnesene polyol (A2) is, for example, preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and may even be 60% by mass or less.

The mass ratio (A1):(A2) of the cardanol polyol (A1) to the farnesene polyol (A2) is preferably 10:90 to 80:20. By setting the mass ratio within this range, it becomes easier to achieve both low dielectric properties and hardness. The mass ratio (A1):(A2) is more preferably 20:80 to 70:30, even more preferably 30:70 to 60:40, and may be 40:60 to 60:40.

When polyol (A) contains another polyol (A3) such as polybutadiene polyol, the content of the other polyol (A3) in 100% by mass of polyol (A) may be, for example, 5 to 50% by mass or 10 to 40% by mass.

[Other ingredients]
In addition to the components described above, various additives such as catalysts, plasticizers, antioxidants, foam stabilizers, diluents, flame retardants, ultraviolet absorbers, colorants, and fillers may be added to the first component as needed, provided that the object of this embodiment is not impaired.

The catalyst may be, for example, a metal catalyst such as an organotin catalyst, an organolead catalyst, or an organobismuth catalyst, or a variety of urethane polymerization catalysts such as an amine catalyst.

Examples of plasticizers include phthalate diesters such as dioctyl phthalate, diisononyl phthalate, and diundecyl phthalate; adipic acid diesters such as dioctyl adipate and diisononyl adipate; trimellitate esters such as trioctyl trimellitate and triisononyl trimellitate; pyromellitate esters such as tetraoctyl pyromellitate and tetraisononyl pyromellitate; and phosphate triesters such as tricresyl phosphate, trixylenyl phosphate, and cresyl diphenyl phosphate. These may be used alone or in combination. The content of the plasticizer is not particularly limited and may be, for example, 0.5 to 10% by mass per 100 parts by mass of polyol (A).

<Second component>
[Polyisocyanate (B)]
The polyisocyanate (B) contained in the second component is not particularly limited, and various polyisocyanate compounds having two or more isocyanate groups per molecule can be used. Examples of the polyisocyanate (B) include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates, and any one of these may be used alone or in combination of two or more.

Examples of aliphatic polyisocyanates include tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, and derivatives thereof.

Examples of alicyclic polyisocyanates include isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and derivatives thereof.

Aromatic polyisocyanates include, for example, tolylene diisocyanate (TDI, e.g., 2,4-TDI, 2,6-TDI), diphenylmethane diisocyanate (MDI, e.g., monomeric MDI, polymeric MDI), 4,4'-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate (XDI), 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, and derivatives thereof.

Examples of the above derivatives include isocyanurate-modified products, allophanate-modified products, biuret-modified products, adduct-modified products, and carbodiimide-modified products.

In one embodiment, it is preferable to use a biomass-derived polyisocyanate as polyisocyanate (B). Specifically, it is preferable that polyisocyanate (B) contains 1,5-pentamethylene diisocyanate and/or a derivative thereof. 1,5-pentamethylene diisocyanate and its derivatives can be synthesized from plant-derived biomass raw materials and can increase the biomass content of the cured product. It is also believed to be able to enhance the effect of achieving both low dielectric properties and hardness. Derivatives of 1,5-pentamethylene diisocyanate include isocyanurate-modified products, allophanate-modified products, biuret-modified products, adduct-modified products, and carbodiimide-modified products, with the isocyanurate-modified product being preferred.

In one embodiment, when 1,5-pentamethylene diisocyanate and/or its derivatives are used as polyisocyanate (B), the amount is not particularly limited, but is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass or more, per 100% by mass of polyisocyanate (B), and may be 100% by mass.

Polyisocyanate (B) may be composed solely of difunctional compounds, or may also contain trifunctional or higher functional compounds, but preferably contains trifunctional or higher functional polyisocyanates.

The isocyanate value of polyisocyanate (B) may be, for example, 100 to 700 mgKOH/g, 200 to 500 mgKOH/g, or 300 to 450 mgKOH/g. In this specification, the isocyanate value (NCOV) is calculated using the isocyanate content measured in accordance with Method A of JIS K1603-1:2007, as follows: Isocyanate value = {(Isocyanate content) × 56110}/(42.02 × 100).

[Other ingredients]
The second component may be composed of only the polyisocyanate (B). Alternatively, in addition to the polyisocyanate (B), various additives such as a catalyst, an antioxidant, a foam stabilizer, a diluent, a flame retardant, an ultraviolet absorber, a colorant, a filler, and a plasticizer may be added as needed, provided that the object of this embodiment is not impaired.

<Two-component curing polyurethane resin composition>
The two-component curing polyurethane resin composition according to this embodiment is typically composed of a first component (a first liquid) and a second component (a second liquid). However, in addition to the first and second components, the composition may also include a third component as the third liquid, which contains the other components described above as optional components.

The two-component curing polyurethane resin composition can be produced by separately preparing the first and second components; that is, the first and second components may be filled in separate containers. The first and second components filled in separate containers may be mixed at the time of use, causing the polyol (A) and polyisocyanate (B) to react to form a polyurethane resin, which may then be cured. At this time, the polyurethane resin may be cured by heating. The two-component curing polyurethane resin composition according to the embodiment may be obtained by mixing the first and second components, and may be in a liquid state before curing, or may be cured.

In this two-component curing polyurethane resin composition, the content of polyisocyanate (B) is not particularly limited, and may be, for example, 5 to 70 parts by mass or 10 to 50 parts by mass per 100 parts by mass of polyol (A).

In this two-component curing polyurethane resin composition, the NCO/OH (index) is not particularly limited and may be, for example, 0.60 to 1.50, 0.80 to 1.40, 1.00 to 1.30, or 1.05 to 1.20. Here, NCO/OH is the molar ratio of isocyanate groups contained in polyisocyanate (B) to hydroxy groups contained in polyol (A). NCO/OH is calculated using the hydroxyl value of polyol (A) and the isocyanate value of polyisocyanate (B).

The two-component curing polyurethane resin composition preferably has a biomass content of 60% or more in the cured product. The biomass content is more preferably 70% or more, and even more preferably 80% or more. Since a higher biomass content is preferable, there is no particular upper limit, but it may be, for example, 95% or less.

In this specification, the biomass content of the cured product is a value obtained by adding the biocontent (%) of each biomass-derived raw material that constitutes the two-component curing polyurethane resin composition according to their mass ratio (i.e., the mass ratio of the biomass-derived raw material to the total mass of the cured product). Here, the biocontent (%) of each biomass-derived raw material is measured in accordance with ASTM D6866-21.

For example, let the biocontent (%) of the cardanol polyol (A1) _{be C1} , and the mass ratio (% by mass) of the cardanol polyol (A1) to the total mass of the cured product be _D1 . Let the biocontent (%) of the farnesene polyol (A2) be _C2 , and the mass ratio (% by mass) of the farnesene polyol (A2) to the total mass of the cured product be _D2 . Let the biocontent (%) of the biomass-derived polyisocyanate be _C3 , and the mass ratio (% by mass) of the biomass-derived polyisocyanate to the total mass of the cured product be _D3 . Then, the biomass degree of the cured product is calculated by the following formula.
Biomass ratio (%) = C ₁ × D ₁ /100 + C ₂ × D ₂ /100 + C ₃ × D ₃ /100

<Uses of two-component curing polyurethane resin composition>
The use of the two-component curing polyurethane resin composition according to this embodiment is not particularly limited, but it is preferably used for sealing electrical and electronic components. Examples of electrical and electronic components include transformers such as transformer coils, choke coils, and reactor coils, device control boards, sensors, and wireless communication components. The two-component curing polyurethane resin composition has excellent low dielectric properties (i.e., a low dielectric constant) and is less susceptible to radio wave interference. Therefore, the two-component curing polyurethane resin composition is preferably used as a sealant for resin-sealing, i.e., covering, wireless communication components that perform wireless communication to protect them from the external environment. For example, it may be used as a sealant for sensors that transmit detected information via wireless communication.

Electrical and electronic components encapsulated with the two-component curing polyurethane resin composition according to this embodiment can be used in, for example, electric washing machines, toilet seats, water heaters, water purifiers, bathtubs, dishwashers, solar panels, power tools, automobiles, motorcycles, etc.

The two-component curing polyurethane resin composition will be described in detail below based on examples and comparative examples, but the present invention is not limited thereto.

The raw materials used in the examples and comparative examples are listed below.

[Polyol (A)]
Farnesene polyol 1: Polyfarnesene diol represented by the above formula (2), "KRASOL F3000 (product name)" manufactured by Cray Valley, hydroxyl value 37 mg KOH/g, number average molecular weight (Mn) 3000, microstructure (1,4-addition structural unit 60% by mass, 3,4-addition structural unit 40% by mass), biocontent 97%
Cardanol polyol 1: Novolac cardanol polyol represented by the above formula (1), "Cardolite NX-9001LV (product name)" manufactured by Cardolite Co., Ltd., hydroxyl value 175 mg KOH/g, average functionality 3.8, biocontent 91.4%
Cardanol polyol 2: Novolac-type cardanol polyol represented by the above formula (1), "Cardolite LITE-9001 (product name)" manufactured by Cardolite Co., Ltd., hydroxyl value 160 mg KOH/g, average functionality 4.3, biocontent 88%

Polybutadiene polyol: "Polybest HT (product name)" manufactured by EVONIK Corporation, hydroxyl value 47 mg KOH/g, number average molecular weight (Mn) 2800
Castor oil-based polyol: "Castor Oil (product name)" manufactured by Ito Oil Mills, Ltd., hydroxyl value 161 mg KOH/g, Mn 1500, biocontent 100%
Polyether polyol: Polypropylene glycol, "EXCENOL 903 (product name)" manufactured by AGC Co., Ltd., hydroxyl value 112 mg KOH/g, Mn 941
Isoprene glycol: hydroxyl value 1079 mg KOH/g, molecular weight 104
Octanediol: hydroxyl value 768 mg KOH/g, molecular weight 146
Dipropylene glycol: hydroxyl value 836 mg KOH/g, molecular weight 134

[Polyisocyanate (B)]
Polyisocyanate 1: Isocyanurate modified product of 1,5-pentamethylene diisocyanate, "Stabio D-376N (product name)" manufactured by Mitsui Chemicals, Inc., isocyanate value 321 mg KOH/g, biocontent 67%
Polyisocyanate 2: Polymeric MDI, "Lupranate M5S (product name)" manufactured by BASF INOAC Polyurethanes Co., Ltd., isocyanate value 428 mg KOH/g
Polyisocyanate 3: HDI isocyanurate modified product, "Duranate TLA-100 (product name)" manufactured by Asahi Kasei Corporation, isocyanate value 311 mg KOH/g

[Other ingredients]
Tin-based catalyst: "Neostan U-810 (product name)" manufactured by Nitto Kasei Co., Ltd.
Plasticizer: Diundecyl phthalate, Sanso Cizer DUP (product name) manufactured by New Japan Chemical Co., Ltd.

[Examples 1 to 8 and Comparative Examples 1 to 8]
Two-component curing polyurethane resin compositions for each Example and Comparative Example were prepared according to the formulations (parts by mass) shown in Tables 1 and 2 below. For preparation, a predetermined amount of the first component shown in Tables 1 and 2 was weighed out, stirred and mixed while appropriately heated to dissolve the components, and then adjusted to 25°C after mixing. Subsequently, the second component, also adjusted to 25°C, was added to this mixture in the formulation ratio (parts by mass of the second component relative to 100 parts by mass of the first component) and NCO/OH (index) shown in Tables 1 and 2, stirred and mixed, and degassed.

Tables 1 and 2 show the biomass content of the cured product for each two-component curing polyurethane resin composition.

The compatibility, dielectric constant, and hardness of each two-component curing polyurethane resin composition were measured and evaluated. The measurement and evaluation methods are as follows:

[Compatibility]
The state of the liquid after mixing with the first component was checked, and the compatibility of the polyol was evaluated according to the following criteria: For samples D and E, in which separation occurred in the first component in this evaluation, the compatibility of the polyol was poor, and measurement and evaluation as a two-component curable polyurethane resin composition could not be carried out, so evaluation of the dielectric constant and hardness was not carried out.
A: Transparent B: Slightly cloudy C: Cloudy D: Separation occurred after 30 minutes or more E: Separation occurred in less than 30 minutes

[Dielectric constant]
The dielectric constant at 1 MHz was measured in accordance with JIS C2138:2007. Specifically, the degassed two-component curing polyurethane resin composition was poured into a 3 mm thick mold and cured at 80°C for 16 hours (overnight) to produce a 3 mm thick resin sheet. The resin sheet was cut into 50 mm x 50 mm x 3 mm sheets to serve as measurement samples. The measurement was performed using an instrument manufactured by Agilent Technologies (main body model: E4980A, name: Precision LCR Meter; electrode part model: 16451B, name: DIELECTRIC TEST FIXTURE), and the dielectric constant (relative permittivity) at a frequency of 1 MHz was measured.

[hardness]
Measurements were made using a Type A durometer as described in JIS K7215:1986. Specifically, the degassed two-component curing polyurethane resin composition was poured into a 200 mL cup and cured at 80°C for 16 hours (overnight) to produce a cured resin. The test specimen had a thickness of 6 mm or more and a width of approximately 25 mm or more. The test was performed by placing the test specimen on a flat, solid surface, and pressing the pressure reference surface of the durometer against the sample surface as quickly as possible without impact, while keeping it parallel to the sample surface, to ensure good contact between the pressure reference surface and the sample. The maximum indicated value on the indicator's pointer was then quickly read, and the evaluation was performed according to the following criteria.
A: Hardness of 25 or more B: Hardness of 20 or more and less than 25 C: Hardness of 15 or more and less than 20 D: Hardness of 10 or more and less than 15 E: Hardness less than 10

The results are shown in Tables 1 and 2. Comparative Examples 1 and 2, which used only farnesene polyol as the polyol without using cardanol polyol, exhibited excellent low-dielectric properties but did not achieve sufficient hardness. Comparative Example 3, which used a combination of farnesene polyol and castor oil-based polyol, also did not achieve sufficient hardness. On the other hand, Comparative Example 4, which used a combination of farnesene polyol and polyether polyol, achieved sufficient hardness but exhibited a significantly increased dielectric constant and poor low-dielectric properties. Comparative Examples 5, 6, and 8, which used a combination of farnesene polyol and isoprene glycol, octanediol, or dipropylene glycol, exhibited poor compatibility with the first component. Comparative Example 7, which used only cardanol polyol as the polyol without using farnesene polyol, achieved sufficient hardness but poor low-dielectric properties.

In contrast, Examples 1 to 8, which used a combination of cardanol polyol and farnesene polyol as the polyol, had a dielectric constant of 3.1 or less, exhibiting excellent low dielectric properties, and also achieved a hardness rating of A to C, indicating sufficient hardness. Furthermore, all of Examples 1 to 8 had a biomass content of 60% or more, achieving both low dielectric properties and hardness while using biomass-derived raw materials.

Comparing Example 1 with Examples 4 and 8, it was found that when 1,5-pentamethylene diisocyanate and/or its derivatives were used as the polyisocyanate, not only was the biomass content high, but the hardness was also high, resulting in an excellent combination of low dielectric properties and hardness.

The various numerical ranges described in this specification can each be combined with any upper and lower limit, and all such combinations are considered to be preferred numerical ranges and are described in this specification. Furthermore, a numerical range described as "X to Y" means greater than or equal to X and less than or equal to Y.

Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their omissions, substitutions, modifications, etc. are included within the scope and spirit of the invention, as well as within the scope of the inventions and their equivalents as set forth in the claims.

Claims (8)

A first component including a polyol and a second component including a polyisocyanate,
The polyol comprises a cardanol polyol and a farnesene polyol.
A two-component curing polyurethane resin composition. The two-component curing polyurethane resin composition according to claim 1, wherein the mass ratio of the cardanol polyol to the farnesene polyol is 10:90 to 80:20. The two-component curing polyurethane resin composition according to claim 1 or 2, wherein the cardanol polyol is a novolac cardanol polyol. The two-component curing polyurethane resin composition according to any one of claims 1 to 3, wherein the farnesene polyol is a polyfarnesene diol. The two-component curable polyurethane resin composition according to any one of claims 1 to 4, wherein the polyisocyanate includes 1,5-pentamethylene diisocyanate and/or a derivative thereof. The two-component curing polyurethane resin composition according to any one of claims 1 to 5, wherein the biomass content of the cured product is 60% or more. The two-component curing polyurethane resin composition according to any one of claims 1 to 6, which is used for sealing electrical and electronic components. An electric/electronic part resin-sealed with the two-component curing polyurethane resin composition according to any one of claims 1 to 7.