JP6905135B1 - Polyurethane resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane resin composition having excellent heat resistance. A polyurethane resin composition according to an embodiment contains a hydroxyl group-containing compound (A), an isocyanate group-containing compound (B), a metal hydroxide (C), and a plasticizer (D). The hydroxyl group-containing compound (A) contains a polybutadiene polyol (A1), and the average hydroxyl value of the polybutadiene polyol (A1) is 60 to 100 mgKOH / g. The plasticizer (D) consists only of a phthalate ester having a boiling point of 300 ° C. or higher. The polyurethane resin composition has a mass reduction rate of 1.5% or less after treatment at 100 ° C. × 1000 h, and an elastic modulus change rate (10 Hz) at −40 ° C. after treatment at 100 ° C. × 1000 h is 100% or less. .. [Selection diagram] None

Description

The present invention relates to polyurethane resin compositions.

Conventionally, electronic circuit boards and electronic components have been sealed with a polyurethane resin or the like in order to prevent contamination from the outside (see, for example, Patent Document 1). In these applications, the stress on the member due to the cold heat cycle is increased, and it is required to have high heat resistance, that is, to maintain flexibility for a long period of time.

Patent Document 2 describes a polyurethane resin composition in which a polyol compound contains a polybutadiene polyol having a hydroxyl value of 60 mgKOH / g or less, with an object of providing a polyurethane resin having excellent compatibility, workability, and excellent thermal cycle characteristics. A polyurethane resin composition containing 50 to 85% by mass of an inorganic filler and 1 to 30% by mass of a plasticizer with respect to 100% by mass is disclosed.

Japanese Unexamined Patent Publication No. 2016-020439 Japanese Patent No. 6499347

However, in the conventional polyurethane resin composition, the flexibility may be impaired due to the vaporization of the plasticizer after long-term use, and the heat resistance is not always sufficient.

An embodiment of the present invention has been made in view of the above problems, and an object of the present invention is to provide a polyurethane resin composition having excellent heat resistance.

The present invention includes embodiments shown below.
[1] A polyurethane resin composition containing a hydroxyl group-containing compound (A), an isocyanate group-containing compound (B), a metal hydroxide (C), and a plasticizer (D), wherein the hydroxyl group-containing compound (A) is used. However, the plasticizer (D) contains only a phthalate ester having a polybutadiene polyol (A1), an average hydroxyl value of the polybutadiene polyol (A1) of 60 to 100 mgKOH / g or less, and a plasticizer (D) having a boiling point of 300 ° C. or higher. A polyurethane resin composition having a mass loss rate of 1.5% or less after treatment at 100 ° C. × 1000 h and an elastic rate change rate (10 Hz) at −40 ° C. at −40 ° C. after treatment at 100 ° C. × 1000 h.
[2] The mass reduction rate after 100 ° C. × 1000 h treatment is 1.0% or less, and the elastic modulus change rate (10 Hz) at −40 ° C. after 100 ° C. × 1000 h treatment is 50% or less [1]. The polyurethane resin composition according to.
[3] The polyurethane resin composition according to [1] or [2], which is used for electrical and electronic parts.

According to the embodiment of the present invention, it is possible to provide a polyurethane resin composition having excellent heat resistance by suppressing the vaporization of the plasticizer.

The polyurethane resin composition according to this embodiment contains a hydroxyl group-containing compound (A), an isocyanate group-containing compound (B), a metal hydroxide (C), and a plasticizer (D).

[Hydroxy group-containing compound (A)]
The hydroxyl group-containing compound (A) contains a polybutadiene polyol (A1), and the average hydroxyl value of the polybutadiene polyol (A1) is 60 to 100 mgKOH / g. As the polybutadiene polyol (A1), one kind of polybutadiene polyol may be used alone, or two or more kinds of polybutadiene polyols may be used in combination.

Here, the "average hydroxyl value" is the value of the hydroxyl value of the one type of polybutadiene polyol when used alone, and the hydroxyl value of the plurality of polybutadiene polyols when two or more types are used in combination. It is the average value of hydroxyl values calculated by multiplying by the ratio and adding them together. In the present specification, the hydroxyl value is measured according to the method A of JIS K1557-1: 2007.

As the polybutadiene polyol (A1), a known terminal hydroxyl group polybutadiene used for polyurethane resin can be used, and if the average hydroxyl value is 60 to 100 mgKOH / g, the polybutadiene polyol or hydroxyl group having a hydroxyl value of less than 60 mgKOH / g can be used. Even a polybutadiene polyol having a value exceeding 100 mgKOH / g can be used in combination with another polybutadiene polyol.

The lower limit of the average hydroxyl value of the polybutadiene polyol (A1) is as described above from the viewpoint of lowering the viscosity of the polyurethane resin composition before curing and improving workability when combined with the high boiling point plasticizer (D). It is 60 mgKOH / g or more. The lower limit of the average hydroxyl value of the polybutadiene polyol (A1) is more preferably 70 mgKOH / g or more, still more preferably 72 mgKOH / g or more. The upper limit of the average hydroxyl value of the polybutadiene polyol (A1) is 100 mgKOH / g or less, and may be 90 mgKOH / g or less.

The hydroxyl group-containing compound (A) may further contain a hydroxyl group-containing compound other than the polybutadiene polyol (A1) (hereinafter, referred to as “hydroxyl group-containing compound (A2)”). Examples of the hydroxyl group-containing compound (A2) include a polyol (A3) generally used as a main raw material for a polyurethane resin, a low molecular weight polyol (A4) used as a cross-linking agent, and the like.

The polyol (A3) is a compound having a plurality of hydroxyl groups in the molecule, and examples thereof include various polyols other than the polybutadiene polyol. Examples of the polyol (A3) include castor oil-based polyols, polyether polyols, polyester polyols, polycarbonate polyols, dimeric acid polyols, polycaprolactone polyols, acrylic polyols, polyisoprene polyols, hydrides of polybutadiene polyols, and hydrogen of polyisoprene polyols. Examples thereof include compounds, and any one of these may be used or two or more thereof may be used in combination. Among these, castor oil-based polyol (A31) is preferably used as the polyol (A3). By using the castor oil-based polyol (A31) in combination with the polybutadiene polyol (A1), the viscosity of the polyurethane resin composition before curing can be reduced, and the compatibility with the isocyanate group-containing compound (B) is improved. do.

As the castor oil-based polyol (A31), castor oil, castor oil fatty acid, and a polyol produced by hydrogenating castor oil or hydrogenated castor oil fatty acid can be used. Examples of such polyols include castor oil, transesterified castor oil and other natural fats and oils, reaction products of castor oil and polyhydric alcohols, esterification reactions of castor oil fatty acids and polyhydric alcohols, and alkylene oxides thereof. Examples thereof include a polyol obtained by transesterifying the above. The hydroxyl value of the castor oil-based polyol (A31) is not particularly limited, but is preferably 50 to 250 mgKOH / g, and more preferably 120 to 180 mgKOH / g.

Examples of the low molecular weight polyol (A4) include polyhydric alcohols having a molecular weight of 300 or less, and more specifically, for example, N, N-bis (2-hydroxypropyl) aniline, hydroquinone-bis (β-hydroxyethyl) ether, and the like. Aromatic alcohols such as resorcinol-bis (β-hydroxyethyl) ether, aliphatic alcohols such as ethylene glycol, 1,4-butanediol, octanediol, trimethylolpropane, and triisopropanolamine can be mentioned, and any one of these can be mentioned. You may use seeds or use two or more kinds together.

In one embodiment, the hydroxyl group-containing compound (A) is preferably composed of only the polybutadiene polyol (A1) or only the polybutadiene polyol (A1) and the polyol (A3), and the low molecular weight polyol (A4) is composed of only the polybutadiene polyol (A1) and the polyol (A3). It is preferable not to contain it. More preferably, the hydroxyl group-containing compound (A) is composed of only the polybutadiene polyol (A1), or is composed of only the polybutadiene polyol (A1) and the castor oil-based polyol (A31).

The content of the hydroxyl group-containing compound (A) is not particularly limited, and may be 3 to 30% by mass, 5 to 25% by mass, or 6 to 20% by mass with respect to 100% by mass of the polyurethane resin composition. , 7 to 20% by mass may be used.

The content of the polybutadiene polyol (A1) is not particularly limited, but may be 3 to 25% by mass, 5 to 25% by mass, or 6 to 20% by mass with respect to 100% by mass of the polyurethane resin composition. It may be 7 to 16% by mass.

When the polyol (A3) (preferably castor oil-based polyol (A31)) is blended, the content thereof is not particularly limited, but may be 0.1 to 10% by mass with respect to 100% by mass of the polyurethane resin composition. It may be 0.5 to 5% by mass, or 0.5 to 3% by mass. The mixing ratio of the polybutadiene polyol (A1) and the polyol (A3) is not particularly limited, and the mass ratio (A1) / (A3) may be 50/50 to 95/5, and 60/40 to 90/10. But it may be.

[Isocyanate group-containing compound (B)]
The isocyanate group-containing compound (B) is not particularly limited, and various polyisocyanate compounds can be used. Examples thereof include an aliphatic polyisocyanate compound (B1), an alicyclic polyisocyanate compound (B2), an aromatic polyisocyanate compound (B3), an aromatic aliphatic polyisocyanate compound (B4), and modified products thereof. Any one of them may be used or two or more of them may be used in combination. Among these, it is preferable to use a modified polyisocyanate compound from the viewpoint of reactivity, durability, viscosity and workability.

Examples of the aliphatic polyisocyanate compound (B1) include tetramethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate. Examples thereof include 2-methylpentane-1,5-diisocyanate and 3-methylpentane-1,5-diisocyanate.

Examples of the alicyclic polyisocyanate compound (B2) include isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexanediisocyanate, methylcyclohexylene diisocyanate, and 1,3-bis ( Isocyanate methyl) cyclohexane and the like.

Examples of the aromatic polyisocyanate compound (B3) include toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), and 4,4'-diisocyanate. Examples thereof include benzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylenediocyanate, and 1,4-phenylenedi isocyanate.

Examples of the aromatic aliphatic polyisocyanate compound (B4) include dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, α-tetramethylxylylene diisocyanate and the like.

Examples of the modified products of these polyisocyanate compounds (B1) to (B4) include isocyanurate modified products, allophanate modified products, bullet modified products, adduct modified products, and carbodiimide modified products. One embodiment includes an isocyanurate modified product of an aliphatic polyisocyanate compound (B1) and a carbodiimide modified product of an aromatic polyisocyanate compound (B3).

The content of the isocyanate group-containing compound (B) is not particularly limited, and may be 0.5 to 15% by mass, 1 to 10% by mass, or 1.5 to 1% by mass with respect to 100% by mass of the polyurethane resin composition. It may be 5% by mass.

[Metal hydroxide (C)]
Examples of the metal hydroxide (C) include aluminum hydroxide and / or magnesium hydroxide, and aluminum hydroxide is preferably used.

The content of the metal hydroxide (C) is not particularly limited, and may be 40 to 85% by mass or 50 to 75% by mass with respect to 100% by mass of the polyurethane resin composition. When the content of the metal hydroxide (C) is 40% by mass or more, the flame retardancy can be improved, and when it is 85% by mass or less, the viscosity of the polyurethane resin composition before curing is reduced. can do.

[Plasticizer (D)]
As the plasticizer (D), a phthalate ester having a boiling point of 300 ° C. or higher is used. By using only a phthalate ester having a boiling point of 300 ° C. or higher as the plasticizer (D), it is possible to suppress the vaporization of the plasticizer (D) when the cured polyurethane resin composition is placed in a high temperature environment. Flexibility can be maintained and heat resistance can be improved in long-term use. On the other hand, since a plasticizer having a high boiling point generally has a large molecular weight, it becomes a factor for increasing the viscosity of the polyurethane resin composition before curing. On the other hand, by setting the average hydroxyl value of the polybutadiene polyol (A1) to 60 mgKOH / g or more, more preferably 70 mgKOH / g or more as described above, the polyurethane resin is used even when a plasticizer having a high boiling point is used. It is possible to suppress an increase in viscosity of the composition before curing, and it is possible to improve workability.

In the present specification, the boiling point of the plasticizer (D) is measured by JIS K 2233 (standard air pressure: 1013 hPa).

Examples of the phthalate ester of the plasticizer (D) having a boiling point of 300 ° C. or higher include dioctyl phthalate, diisononyl phthalate, diundecyl phthalate, and diisodecyl phthalate. Any one of these phthalates may be used, or two or more thereof may be used in combination.

The content of the plasticizer (D) is not particularly limited, but is preferably 5 to 30% by mass, more preferably 10 to 27% by mass, based on 100% by mass of the polyurethane resin composition. When the content of the plasticizer (D) is 5% by mass or more, the flexibility of the polyurethane resin composition after curing can be improved, and when it is 30% by mass or less, the flexibility from the urethane resin cured product can be improved. Bleed can be suppressed.

[Other ingredients]
The polyurethane resin composition according to the present embodiment further includes a defoaming agent, a catalyst, an antioxidant, a hygroscopic agent, a fungicide, a silane coupling agent, a tackifier, a curing accelerator, and a coloring agent, if necessary. , Amine-based cross-linking agent, filler, flame retardant, ultraviolet absorber and various other additives can be included.

[Polyurethane resin composition]
In the polyurethane resin composition according to the present embodiment, the molar ratio (NCO / OH) of the isocyanate group to the hydroxyl group is not particularly limited, but is preferably 0.6 to 1.5, and more preferably 0.7 to 0.7. It is 1.3.

The method for producing the polyurethane resin composition is not particularly limited, and the polyurethane resin composition can be produced according to a known method. For example, (step 1) a step of preparing a first component containing a hydroxyl group-containing compound (A), (step 2) a step of preparing a second component containing an isocyanate group-containing compound (B), and (step 3) these. Examples thereof include a method including a step of mixing the first component and the second component to obtain a polyurethane resin composition.

The metal hydroxide (C), the plasticizer (E), and various additives as optional components may be contained in either the first component or the second component described above. When a part of the isocyanate group-containing compound (B) is contained together with the hydroxyl group-containing compound (A) in the first component, the first component contains a hydroxyl group-containing compound (A) and an isocyanate group-containing compound (B). It may contain a urethane prepolymer having a hydroxyl group (OH) at the terminal, which is obtained by the reaction. When a part of the hydroxyl group-containing compound (A) is contained together with the isocyanate group-containing compound (B) in the second component, the second component contains an isocyanate group-containing compound (B) and a hydroxyl group-containing compound (A). A urethane prepolymer having an isocyanate group (NCO) at the terminal, which is obtained by the reaction, may be contained.

In the polyurethane resin composition, the hydroxyl group-containing compound (A) and the isocyanate group-containing compound (B) may partially or wholly react to form the polyurethane resin. That is, the polyurethane resin composition may be in a liquid state before curing, or may be a cured product. As a method for curing the polyurethane resin composition, the first component and the second component may be mixed, whereby the hydroxyl group-containing compound (A) and the isocyanate group-containing compound (B) react to form a polyurethane resin. Hardens. At that time, it may be cured by heating.

In the present embodiment, the mass reduction rate of the polyurethane resin composition after treatment at 100 ° C. × 1000 h is 1.5% or less. As a result, vaporization of the plasticizer (D) in a high temperature environment is suppressed, and flexibility can be maintained in long-term use. The mass reduction rate is more preferably 1.0% or less. The lower the mass reduction rate is, the more preferable it is. Therefore, the lower limit is not particularly limited and may be 0%.

Here, the mass reduction rate is determined as a percentage of the mass reduction amount of the test piece before and after the treatment with respect to the mass of the test piece before the treatment by treating the test piece obtained by curing the polyurethane resin composition at 100 ° C. for 1000 hours. ..

In the present embodiment, the elastic modulus change rate (10 Hz) of the polyurethane resin composition at −40 ° C. after treatment at 100 ° C. × 1000 h is 100% or less. As a result, it is possible to suppress a decrease in flexibility due to a long-term cooling / heating cycle, and it is possible to improve heat resistance. The elastic modulus change rate (10 Hz) is preferably 50% or less. The lower the rate of change in elastic modulus (10 Hz) is, the more preferable it is. Therefore, the lower limit is not particularly limited and may be 0%.

Here, the elastic modulus change rate (10 Hz) is the test piece before and after the treatment with respect to the elastic modulus of −40 ° C. of the test piece before treatment by treating the test piece obtained by curing the polyurethane resin composition at 100 ° C. for 1000 hours. It is obtained as a percentage of the increase in elastic modulus at −40 ° C. The elastic modulus at −40 ° C. refers to the elastic modulus obtained by measuring the test piece in an atmosphere of −40 ° C. using a dynamic viscoelasticity measuring machine.

The elastic modulus (10 Hz) of the polyurethane resin composition at −40 ° C. after treatment at 100 ° C. × 1000 h is not particularly limited, but is preferably 100 MPa or less, and more preferably 80 MPa or less.

[Use]
The polyurethane resin composition according to the present embodiment is preferably used for electrical and electronic parts because it has excellent heat resistance. Examples of such electrical and electronic components include transformers such as transformer coils, choke coils and reactor coils, and equipment control boards.

The electrical and electronic parts using the polyurethane resin composition according to the present embodiment are used in, for example, electric washing machines, toilet seats, water heaters, water purifiers, baths, dishwashers, solar panels, electric tools, automobiles, motorcycles, and the like. can do.

Hereinafter, the polyurethane resin composition will be described in detail based on Examples and Comparative Examples, but the present invention is not limited thereto. In addition, "parts" and "%" in an Example represent "parts by mass" and "% by mass", respectively, unless otherwise specified.

The raw materials used in Examples and Comparative Examples are shown below.

[Polybutadiene polyol (A1)]
A1-2: Polybutadiene polyol prepared by the following method An azeotropic mixture 105 containing 150 parts by mass of 1,3-butadiene, 88% by mass of isopropanol and 12% by mass of water in a stirring reactor in which the inside of the system was replaced with nitrogen. A mass portion and 30 parts by mass of a 60% aqueous hydrogen peroxide solution were charged. The contents of the reactor were heated to 120 ° C. with continuous stirring, and kept at 120 ° C. to 130 ° C. with stirring to carry out a polymerization reaction for 2 hours. After completion for a predetermined period of time, the contents of the reactor are cooled, the reaction product is removed from the reactor, unreacted monomers are removed from the reaction product, the product is washed with water to retain isopropanol and unreacted hydrogen peroxide. Was removed. The product was vacuum dried to give a polybutadiene polyol a1-2 having a viscosity of 5000 mPa · s and a hydroxyl value of 80.0 mgKOH / g at 25 ° C.

A1-1: Polybutadiene polyol having a hydroxyl value of 46.6 mgKOH / g (trade name: Poly bd R-45HT, manufactured by Idemitsu Kosan Co., Ltd.)
-A1-3: Polybutadiene polyol having a hydroxyl value of 102.7 mgKOH / g (trade name: Poly bd R-15HT, manufactured by Idemitsu Kosan Co., Ltd.)

[Other hydroxyl group-containing compounds (A2)]
-A2-1: Castor oil fatty acid with hydroxyl value 161 mgKOH / g-polyhydric alcohol ester (divalent number of functional groups) (Product name: Castor oil D, manufactured by Itoh Oil Chemicals Co., Ltd.)
-A2-2: Aromatic alcohol with a hydroxyl value of 529.8 mgKOH / g (trade name: OK All 100, manufactured by Okahata Sangyo Co., Ltd.)
-A2-3: Aliphatic alcohol with a hydroxyl value of 767.5 mgKOH / g (trade name: octanediol, manufactured by KH Neochem Co., Ltd.)

[Isocyanate group-containing compound (B)]
B1: Hexamethylene diisocyanate isocyanurate-modified product (trade name: Duranate TPA-100-D, manufactured by Asahi Kasei Chemicals Co., Ltd.)
B2: Isocyanurate-modified product of hexamethylene diisocyanate (trade name: Duranate TLA-100, manufactured by Asahi Kasei Chemicals Co., Ltd.)
-B3: Hexamethylene diisocyanate (trade name: WANNATE HMDI, manufactured by Manka Kagaku Japan Co., Ltd.)
-B4: Carbodiimide modified product of diphenylmethane diisocyanate (trade name: Millionate MLT, manufactured by Tosoh Corporation)

[Metal hydroxide (C)]
・ C1: Aluminum hydroxide (trade name: aluminum hydroxide C-305, manufactured by Sumitomo Chemical Co., Ltd.)
-C2: Aluminum hydroxide (trade name: BX-053, manufactured by Nippon Light Metal Co., Ltd.)

[Plasticizer (D)]
・ D1: Diisononyl phthalate, boiling point 403 ° C (trade name: DINP, manufactured by J-PLUS Co., Ltd.)
・ D2: Diundecyl phthalate, boiling point 523 ° C (trade name: Sun Sizar DUP, manufactured by Shin Nihon Rika Co., Ltd.)
・ D3: Diisodecyl adipate (trade name: DIDA, manufactured by Taoka Chemical Industry Co., Ltd.)

-Catalyst: Dioctyl tin dilaurate (trade name: Neostan U-810, manufactured by Nitto Kasei Co., Ltd.)

[Examples 1 to 8 and Comparative Examples 1 to 3]
The polyurethane resin compositions of each Example and each Comparative Example were prepared according to the formulations (parts by mass) shown in Table 1 below. In the preparation, among the components shown in Table 1, the components excluding the isocyanate group-containing compound (B) were mixed using a mixer (trade name: Awatori Rentaro, manufactured by Shinky Co., Ltd.) at 2000 rpm for 3 minutes, and then 25. Adjusted to ° C. Subsequently, the isocyanate group-containing compound (B) adjusted to 25 ° C. was added to this mixture, and the mixture was mixed at 2000 rpm for 60 seconds using the same mixer to obtain each polyurethane resin composition.

The viscosity, mass reduction rate and elastic modulus change rate of the obtained polyurethane resin composition were measured and evaluated. The measurement / evaluation method is as follows.

(viscosity)
The obtained polyurethane resin composition was adjusted to 25 ° C., and the viscosity 5 minutes after the start of mixing was measured using a BM type viscometer.

(Mass reduction rate)
1. 1. Preparation of test piece A test piece for evaluation was prepared by pouring the polyurethane resin composition into a mold having a size of 5 cm × 5 cm and a thickness of 1 cm, curing at 80 ° C. for 16 hours, and then removing the mold.

2. Measurement of mass loss rate The test piece was treated at 100 ° C. for 1000 hours, the mass of each test piece before and after the heat treatment was measured at room temperature (23 ° C.), and the mass loss rate was calculated by the following formula.
Mass reduction rate (%) = {(mass of test piece before treatment (g) -mass of test piece after treatment (g)) / (mass of test piece before treatment (g))} × 100

3. 3. Evaluation of the effect of suppressing the vaporization of the plasticizer Based on the result of the mass reduction rate, the effect of suppressing the vaporization of the plasticizer was evaluated according to the following evaluation criteria.
(Evaluation criteria)
◎ (excellent): Mass reduction rate is 1.0% or less ○ (Good): Mass reduction rate is more than 1.0% and 1.5% or less × (Defective): Mass reduction rate is more than 1.5%

(Ratio of change in elastic modulus)
1. 1. Preparation of test piece A test piece for evaluation was prepared by pouring the polyurethane resin composition into a mold having a thickness of 1 cm × 8 cm and a thickness of 3 mm, curing at 80 ° C. for 16 hours, and then removing the mold.
2. Measurement of elastic modulus change rate For the test piece before treatment at 100 ° C. for 1000 hours and the test piece after heat treatment, each under an atmosphere of -40 ° C, a dynamic viscoelasticity measuring machine: DMS (manufactured by SIINanoTechnology): Using DMS6100), the elastic modulus (frequency: 10 Hz) was measured with the deformation mode as the tensile mode. The measurement was performed in accordance with JIS K 7244-4, and the storage elastic modulus E'was measured using a sample cut into a strip of 5 mm × 30 mm × 3 mm as a sample. The measurement conditions are as follows.
Measurement temperature: -100 ° C to 150 ° C
Temperature rise rate: 3 ° C / min
Initial distortion: 0.01%
Initial load: 25g
Using the measured elastic modulus, the elastic modulus change rate was measured by the following formula.
Elastic modulus change rate (%) = {(post-treatment elastic modulus (MPa) -pre-treatment elastic modulus (MPa)) / pre-treatment elastic modulus (MPa)} × 100

3. 3. Evaluation of heat resistance Based on the result of the elastic modulus change rate, the heat resistance was evaluated according to the following evaluation criteria.
(Evaluation criteria)
◎ (Excellent): Elastic modulus change rate is 50% or less ○ (Good): Elastic modulus change rate is more than 50% 100% or less × (Poor): Elastic modulus change rate is more than 100%

The results are shown in Table 1. Comparative Examples 1 to 3 corresponding to Examples of Patent Document 2 are examples in which an adipate ester is used as a plasticizer together with a polybutadiene polyol having a low average hydroxyl value, and the mass reduction rate after heat treatment is large and the plasticizer is used. The effect of suppressing the vaporization of the agent was insufficient, the elastic modulus after the heat treatment increased significantly, and the heat resistance was inferior.

On the other hand, in Examples 1 to 8, the mass reduction rate after the heat treatment was small, the effect of suppressing the vaporization of the plasticizer was excellent, the increase in the elastic modulus after the heat treatment was small, and the heat resistance was excellent. .. Further, although only a high boiling point phthalate ester was used as the plasticizer, the viscosity of the polyurethane resin composition before curing was low, and the workability was excellent.

Although some 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 implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments, omissions, replacements, changes, etc. thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

Since the polyurethane resin composition according to the present embodiment has excellent heat resistance, it can be suitably used for electrical and electronic parts that generate heat.

Claims (3)

A polyurethane resin composition containing a hydroxyl group-containing compound (A), an isocyanate group-containing compound (B), a metal hydroxide (C), and a plasticizer (D).
The hydroxyl group-containing compound (A) contains a polybutadiene polyol (A1), and the average hydroxyl value of the polybutadiene polyol (A1) is 60 to 100 mgKOH / g.
The plasticizer (D) consists only of a phthalate ester having a boiling point of 300 ° C. or higher.
The content of the plasticizer (D) is 10 to 30% by mass with respect to 100% by mass of the polyurethane resin composition.
The mass reduction rate after 100 ° C. × 1000 h treatment is 1.5% or less.
A polyurethane resin composition having an elastic modulus change rate (10 Hz) of −40 ° C. after treatment at 100 ° C. × 1000 h of 100% or less. The mass reduction rate after 100 ° C. × 1000 h treatment is 1.0% or less.
The polyurethane resin composition according to claim 1, wherein the elastic modulus change rate (10 Hz) at −40 ° C. after treatment at 100 ° C. × 1000 h is 50% or less. The polyurethane resin composition according to claim 1 or 2, which is used for electrical and electronic parts.