JP5865537B1 - Polyurethane resin composition for electrical insulation - Google Patents

Abstract

Disclosed is a polyurethane resin composition for electrical insulation that is excellent in adhesion to an adherend and excellent in heat resistance, moisture resistance, and insulation. SOLUTION: (1) A agent obtained from at least one selected from aliphatic diisocyanate and alicyclic diisocyanate and containing a polyisocyanate component containing a biuret group; and (2) B containing a polyol component. A polyurethane resin composition for electrical insulation comprising an agent. [Selection figure] None

Description

  The present invention relates to a polyurethane resin composition for electrical insulation, a sealing material comprising the polyurethane resin composition for electrical insulation, and an electrical component resin-sealed using the sealing material.

In recent years, the density and integration of electric and electronic parts have been increased, and improvement of reliability is required for each part.
In particular, electrical and electronic parts used in car engines, water heaters, and the like are required not only to be moisture-proof at room temperature, but also to be highly reliable even under high temperature and humid heat environments.

  Electrical insulating sealing materials are used for the purpose of protecting such electrical and electronic parts from moisture, dust and other atmospheres, vibrations, shocks, etc., and the materials are generally silicone resins and urethanes. Low hardness and flexible resin such as resin is used.

  Although the above-mentioned silicone resin is excellent in heat resistance, flexibility, and low-temperature characteristics, it does not necessarily have sufficient adhesive strength with the materials that make up electrical components. There is a drawback that cannot be prevented.

  On the other hand, the urethane-based resin has good flexibility, wear resistance, low-temperature curability, electrical characteristics, etc. as its original characteristic properties, and is used as an electrical insulating sealing material. .

  As the isocyanate component of the urethane resin, MDI (diphenylmethane diisocyanate) is generally used. In general, such a urethane-based resin often has insufficient heat resistance. In particular, when used as a sealing material for electrical components in a harsh environment such as the vicinity of an engine, there is a problem that the surface tends to crack over time and the electrical components cannot be protected against moisture for a long time.

  As a polyurethane resin composition for electric parts having heat resistance, for example, an aliphatic and / or alicyclic type for electrically connecting solar cells on a substrate and sealing the solar cells A polyurethane resin has been proposed (see Patent Document 1).

  However, in the polyurethane resin described in Patent Document 1, polyisocyanate having an isocyanurate structure is used, and the compatibility between the polyisocyanate component and the polyol component is not sufficient, and the polyurethane resin composition proposed in Patent Document 1 is used. In the case of using a product, there is a problem that the cured molded product becomes sticky, and the adhesive strength with the adherend is reduced, resulting in a decrease in moisture resistance and a decrease in insulation.

  Further, in Patent Document 2, a polybutadiene polyol (A) and a castor oil-based polyol (B) are contained as a hydroxyl group-containing compound as a polyurethane resin composition having compatibility between a polyisocyanate component and a polyol component and having heat resistance. A polyurethane resin composition containing an isocyanurate-modified polyisocyanate compound (C) as an isocyanate group-containing compound has been proposed. In Patent Document 3, (A) a polyisocyanate and (B) a polybutadiene polyol are used. A polyurethane resin composition obtained by reaction and having a 1,2-vinyl structure ratio in the polybutadiene polyol (B) exceeding 85 mol% has been proposed.

  However, Patent Documents 2 and 3 do not fully study the polyisocyanate component. Even when the polyurethane resin compositions described in Patent Documents 2 and 3 are used for electronic parts, it cannot be said that sufficient performance is obtained in heat resistance, moisture resistance, and insulation. For this reason, there was room for improvement as a polyurethane resin composition for electrical insulation that can be suitably used for various electrical components.

Japanese Patent Laid-Open No. 9-23018 JP 2011-1426 A JP 2010-150472 A

  The present invention has been made in view of the above circumstances, and provides an electrically insulating polyurethane resin composition having excellent adhesion to an adherend and excellent heat resistance, moisture resistance, and insulation. Let it be an issue.

  As a result of intensive studies to achieve the above object, the present inventor used a polyisocyanate component containing a biuret group obtained from a specific diisocyanate as the isocyanate component of the polyurethane resin composition, and used this together with the polyol component. As a result, it was found that a polyurethane resin composition for electrical insulation that can achieve the above object was obtained, and the present invention was completed here.

（式中、Ｒ_４は、水酸基を有していてもよい炭素数３〜２０の直鎖状又は分枝鎖状の２価の不飽和脂肪族炭化水素基であり、ｍは、１〜２０の整数を表す。）で表されるポリオール、及びひまし油系ポリオールから選択される少なくとも１種のポリオールを含む、項１〜３のいずれかに記載の電気絶縁用ポリウレタン樹脂組成物。
５．前記ポリオール成分は、１,４結合を６０モル％以上有するポリブタジエンポリオール、及びひまし油系ポリオールから選択される少なくとも１種のポリオールを含む、項１〜４のいずれかに記載の電気絶縁用ポリウレタン樹脂組成物。
６．項１〜５のいずれかに記載の電気絶縁用ポリウレタン樹脂組成物からなる封止材。
７．項６に記載の封止材を用いて樹脂封止された電気部品。 That is, the present invention provides the following polyurethane resin composition for electrical insulation, a sealing material and a resin-sealed electrical component.
1. (1) Agent A containing a polyisocyanate component containing at least one selected from aliphatic diisocyanate and alicyclic diisocyanate and containing a biuret group;
(2) A polyurethane resin composition for electrical insulation comprising a B agent containing a polyol component.
2. The polyisocyanate component contains a uretdione group, and the molar ratio (a) / (b) between the biuret group (a) and the uretdione group (b) of the polyisocyanate component is 100/0 to 60/40. Item 2. The polyurethane resin composition for electrical insulation according to Item 1.
3. Item 2. The polyurethane resin composition for electrical insulation according to Item 1, wherein the molar ratio (a) / (b) between the biuret group (a) and the uretdione group (b) of the polyisocyanate component is 100/0 to 70/30. object.
4). The polyol component has the following general formula (1):

(In the formula, R ₄ is a C 3-20 linear or branched divalent unsaturated aliphatic hydrocarbon group which may have a hydroxyl group, and m is 1-20. The polyurethane resin composition for electrical insulation according to any one of Items 1 to 3, comprising at least one polyol selected from a polyol represented by (2) and a castor oil-based polyol.
5. Item 5. The polyurethane resin composition for electrical insulation according to any one of Items 1 to 4, wherein the polyol component includes at least one polyol selected from polybutadiene polyol having 1,4 bonds of 60 mol% or more and castor oil-based polyol. object.
6). Item 6. A sealing material comprising the polyurethane resin composition for electrical insulation according to any one of Items 1 to 5.
7). Item 7. An electrical component resin-sealed using the sealing material according to Item 6.

  The polyurethane resin composition for electrical insulation of the present invention is obtained from (1) at least one selected from aliphatic diisocyanates and alicyclic diisocyanates, and contains an A agent containing a polyisocyanate component containing a biuret group; 2) By including the B agent containing a polyol component, it is excellent in adhesiveness to the adherend, and is excellent in heat resistance, moisture resistance, and insulation. For this reason, it can use suitably with respect to various electrical components.

  The polyurethane resin composition for electrical insulation of the present invention is obtained from (1) at least one selected from aliphatic diisocyanates and alicyclic diisocyanates, and contains an A agent containing a polyisocyanate component containing a biuret group; 2) It contains B agent containing a polyol component, It is characterized by the above-mentioned.

  The polyurethane resin composition for electrical insulation according to the present invention having the above characteristics is obtained from at least one selected from aliphatic diisocyanate and alicyclic diisocyanate as a polyisocyanate component, and contains a biuret group. Since the polyisocyanate component is used, a decrease in the compatibility between the polyisocyanate component and the polyol component due to the high polarity of the polyisocyanate component can be suppressed. Since such a polyurethane resin composition is excellent in compatibility between the polyisocyanate component and the polyol component, it can suppress the occurrence of stickiness of the resin-cured molded product, and thus has excellent adhesion to the adherend. In addition, it has excellent heat resistance, moisture resistance, and insulation.

  Such a polyurethane resin composition for electrical insulation of the present invention is suitable as a sealing material used for sealing various electrical components.

  Hereinafter, each component of the polyurethane resin composition for electrical insulation of the present invention will be specifically described.

  The polyurethane resin composition for electrical insulation of the present invention (hereinafter also simply referred to as “polyurethane resin composition”) is obtained from at least one selected from (1) aliphatic diisocyanate and alicyclic diisocyanate, and biuret. A two-component polyurethane resin composition comprising an A agent containing a polyisocyanate component containing a group and (2) a B agent containing a polyol component, wherein the A agent and the B agent are mixed at the time of use. Used.

Agent A The polyurethane resin composition for electrical insulation of the present invention comprises an agent A containing a polyisocyanate component containing a biuret group, obtained from at least one selected from aliphatic diisocyanates and alicyclic diisocyanates.

(Aliphatic diisocyanate)
The aliphatic diisocyanate is a compound having a chain aliphatic hydrocarbon and not having an aromatic hydrocarbon when an isocyanate group is excluded from the molecule. The aliphatic diisocyanate is not particularly limited, and examples thereof include butane diisocyanate, pentane diisocyanate, hexamethylene diisocyanate (hereinafter also referred to as “HDI”), trimethylhexamethylene diisocyanate, and lysine diisocyanate. Use of such an aliphatic diisocyanate is more preferable because the resulting polyisocyanate component has a low viscosity.

(Alicyclic diisocyanate)
The said alicyclic diisocyanate is a compound which has the cycloaliphatic hydrocarbon which does not have aromaticity in a molecule | numerator. Although it does not specifically limit as alicyclic diisocyanate, For example, isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, 1, 4- cyclohexane diisocyanate etc. are mentioned.
Among the above aliphatic diisocyanates and alicyclic diisocyanates, HDI, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate are preferable because they are easily available industrially, and HDI is more preferable. By using HDI, the weather resistance and flexibility of the coating film obtained from the polyisocyanate composition are more excellent.

  Aliphatic diisocyanates and alicyclic diisocyanates may be used alone or in combination of two or more.

  The polyisocyanate component used in the polyurethane resin composition of the present invention contains a biuret group represented by the following formula (2).

  When the polyisocyanate component contains a biuret group, the polyurethane resin composition of the present invention is excellent in adhesion to an adherend and exhibits excellent heat resistance and moisture resistance.

  In addition to the polyisocyanate containing a biuret group, the polyisocyanate component includes other bonding groups such as an isocyanurate group, a uretdione group, an allophanate group, a urethane group, a urea group, an oxadiazinetrione group, and an iminooxadiazinedione group. It may contain polyisocyanate. Especially, it is preferable that the polyisocyanate which has an isocyanurate group is included at the point which the heat resistance of a polyurethane resin composition improves.

  The content of the biuret group is 10 mol with respect to a total of 100 mol% of the biuret group, uretdione group, isocyanurate group, allophanate group, urethane group, urea group, oxadiazinetrione group and iminooxadiazinedione group. % Or more is preferable, 20 mol% or more is more preferable, 30 mol% or more is further preferable, and 50 mol% or more is particularly preferable. The content of linking groups other than the biuret group and the uretdione group can be determined by 13C-NMR or 1H-NMR.

  It is preferable that the said polyisocyanate component contains the polyisocyanate which has a uretdione group shown by following formula (3) from the point of low viscosity among the above-mentioned polyisocyanate.

  In the polyisocyanate component used in the polyurethane resin composition of the present invention, the molar ratio (a) / (b) between the biuret group (a) and the uretdione group (b) is preferably 100/0 to 60/40. More preferably, it is 100 / 0-70 / 30, More preferably, it is 100 / 0-80 / 20. When the molar ratio between the biuret group and the uretdione group is within the above range, the heat resistance is more excellent. The molar ratio (a) / (b) between the biuret group (a) and the uretdione group (b) can be determined by 13C-NMR.

  In addition to the biuret group and the uretdione group, the above-mentioned polyisocyanate component may contain the other bonding groups described above. The content of other linking groups was 60 with respect to a total of 100 mol% of biuret group, uretdione group, isocyanurate group, allophanate group, urethane group, urea group, oxadiazinetrione group and iminooxadiazinedione group. The mol% or less is preferable, 50 mol% or less is more preferable, and 40 mol% or less is more preferable. The content of linking groups other than biuret groups and uretdione groups can be determined by 13C-NMR or 1H-NMR.

  The molar ratio (a) / (b) between the biuret group (a) and the uretdione group (b) in the polyisocyanate component can be determined by 13C-NMR as described above. An example of a method for measuring polyisocyanate using HDI as a raw material by 13C-NMR (manufactured by Bruker, FT-NMRDPX-400) is shown below.

Example of 13C-NMR measurement method: A polyisocyanate component is dissolved in deuterium chloroform at a concentration of 10% by mass. The chemical shift standard is 77.0 ppm for the carbon atom signal of deuterium chloroform. The area of the carbon atom signal of the biuret group near 156.4 ppm and the area of the carbon atom signal of the uretdione group near 157.8 ppm are measured. Based on the obtained area, the molar ratio of biuret group and uretdione group in the polyisocyanate component and in the blocked isocyanate composition is calculated by the following formula.
(Biuret group / uretdione group) = (signal area around 156.4 ppm / 2) / (signal area around 157.8 ppm / 2)

  Further, when the polyisocyanate component contains an isocyanurate group in addition to the biuret group and uretdione group, the molar ratio of biuret group, uretdione group and isocyanurate group (biuret group / uretdione group / isocyanurate group) by 13C-NMR. An example of the measurement is shown below.

When measuring the molar ratio (a) / (b) between the biuret group (a) and the uretdione group (b), the area of the carbon atom signal of the isocyanurate group near 149.0 ppm is further measured. Based on the obtained area, the molar ratio of biuret group, uretdione group and isocyanurate group in the polyisocyanate component is calculated by the following formula.
(Biuret group / uretdione group / isocyanurate group) = (signal area around 156.4 ppm / 2) / (signal area around 157.8 ppm / 2) / (signal area around 149.0 ppm / 3)

(Biuretization reaction and uretdioneization reaction)
The polyisocyanate component having a biuret group can be prepared by reacting at least one diisocyanate selected from the group consisting of an aliphatic diisocyanate and an alicyclic diisocyanate with a biuret agent. Although it does not specifically limit as a biuret agent, For example, water, monovalent | monohydric tertiary alcohol, formic acid, hydrogen sulfide, an organic primary monoamine, an organic primary diamine etc. can be mentioned, Preferably it is water.

  The raw material ratio in the biuretization reaction is preferably 0.1 mol or more and 150 mol or less, more preferably 0.2 mol or more and 60 mol or less, and further preferably 0 with respect to 1 mol of the biuretizing agent. .3 mol or more and 20 mol or less. By setting the raw material ratio in the biuretization reaction within the above range, both high production efficiency of the resulting polyisocyanate component and adhesiveness can be achieved.

  A solvent can be used in the biuretization reaction. The solvent dissolves the diisocyanate and a biuretizing agent such as water and forms a homogeneous phase under the reaction conditions. That is, it is preferable to add an amount of a solvent necessary for forming a homogeneous phase. Thereby, production of by-products such as polyurea can be suppressed. A solvent having a low solubility of the biuretizing agent such as water is not preferable because the amount of addition increases accordingly, and the solvent is separated and recovered after completion of the reaction. This solvent preferably has a solubility of a biuretizing agent such as water of 0.5% by mass or more. In addition, the boiling point of the solvent is preferably lower than the boiling point of the raw diisocyanate monomer in consideration of recovery and separation of unreacted diisocyanate and the like. A solvent represented by the following general formula (4) does not react with an isocyanate group, and is hydrophilic and preferable.

In the general formula (4), R ₁ and R ₂ represent an alkyl group or acyl group having 1 to 4 carbon atoms, and both may be the same or different, and R ₃ represents a methyl group or hydrogen. , N represents an integer of 1 to 2.

  Specific examples of the solvent represented by the general formula (4) include, for example, ethylene glycol-based ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, ethylene glycol mono Isopropyl ether acetate, ethylene glycol mono-n-butyl ether acetate, ethylene glycol diacetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol diisopropyl ether, ethylene glycol di-n-butyl ether , Ethylene glycol methyl ethyl ether, ethylene glycol methyl isopropyl ether, ethylene Recall methyl-n-butyl ether, ethylene glycol ethyl-n-propyl ether, ethylene glycol ethyl isopropyl ether, ethylene glycol ethyl-n-butyl ether, ethylene glycol-n-propyl-n-butyl ether, ethylene glycol isopropyl-n-butyl ether, diethylene glycol Monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-propyl ether acetate, diethylene glycol monoisopropyl ether acetate, diethylene glycol mono-n-butyl ether acetate, diethylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, di Tylene glycol di-n-propyl ether, diethylene glycol diisopropyl ether, diethylene glycol di-n-butyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl isopropyl ether, diethylene glycol methyl n-propyl ether, diethylene glycol methyl n-butyl ether, diethylene glycol ethyl isopropyl ether, Examples include diethylene glycol ethyl-n-propyl ether, diethylene glycol ethyl-n-butyl ether, diethylene glycol-n-propyl-n-butyl ether, and diethylene glycol isopropyl-n-butyl ether.

  Other specific examples of the solvent represented by the general formula (4) include, for example, propylene glycol monopropyl ether glycol, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate. , Propylene glycol monoisopropyl ether acetate, propylene glycol mono-n-butyl ether acetate, propylene glycol diacetate, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol diisopropyl ether, propylene glycol di -N-butyl ether, propylene glycol methyl ethyl ether, propylene glycol Methyl isopropyl ether, propylene glycol methyl-n-butyl ether, propylene glycol ethyl-n-propyl ether, propylene glycol ethyl isopropyl ether, propylene glycol ethyl-n-butyl ether, propylene glycol-n-propyl-n-butyl ether, propylene glycol isopropyl- n-butyl ether, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol mono-n-propyl ether acetate, dipropylene glycol monoisopropyl ether acetate, dipropylene glycol mono-n-butyl ether acetate, dipropylene Glycol diacetate, dipropylene glycol Dimethyl ether, Dipropylene glycol diethyl ether, Dipropylene glycol di-n-propyl ether, Dipropylene glycol diisopropyl ether, Dipropylene glycol di-n-butyl ether, Dipropylene glycol methyl ethyl ether, Dipropylene glycol methyl isopropyl ether, Di Propylene glycol methyl-n-propyl ether, dipropylene glycol methyl-n-butyl ether, dipropylene glycol ethyl isopropyl ether, dipropylene glycol ethyl-n-propyl ether, dipropylene glycol ethyl-n-butyl ether, dipropylene glycol-n- Propyl-n-butyl ether, dipropylene glycol isopropyl-n-butyl ether, etc. Can be mentioned.

  Other specific examples of the solvent represented by the general formula (4) are, for example, ethylene glycol solvent such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol diacetate, diethylene glycol. Examples of the propylene glycol solvent include propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol diacetate, and dipropylene glycol dimethyl ether.

  Further, among the solvents represented by the general formula (4), it is preferable to use an alkyl phosphate solvent from the viewpoint that it does not react with an isocyanate group and has hydrophilicity. The alkyl phosphate solvent is not particularly limited, and examples thereof include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and tributyl phosphate, and trimethyl phosphate and triethyl phosphate are preferable.

  These solvents can be used alone or in admixture of two or more. A preferable mixing weight ratio of the solvent is 3/7 to 9/1 of ethylene glycol solvent / phosphoric acid solvent.

  In the biuretization reaction, an OH acidic compound such as di (2-ethylhexyl) phosphate exemplified in JP-A-8-225511 can be added.

  The biuretization reaction temperature is preferably 70 ° C. or higher and 200 ° C. or lower, and more preferably 90 ° C. or higher and 180 ° C. or lower.

  After completion of the reaction, unreacted diisocyanate and solvent may be separated from the polyisocyanate. From the viewpoint of safety, it is preferable to separate the unreacted diisocyanate. Although it does not specifically limit as a method of isolate | separating an unreacted diisocyanate and a solvent, For example, a thin film distillation method and a solvent extraction method are mentioned.

  The polyisocyanate component having a uretdione group can be obtained using a uretdione-forming reaction catalyst. Although it does not specifically limit as a uretdione-ized reaction catalyst, Specifically, Tris phosphines, such as trialkyl phosphine, such as tri-n-butylphosphine and tri-n-octylphosphine, and tris- (dimethylamino) -phosphine ( And tertiary phosphine such as cycloalkylphosphine such as dialkylamino) phosphine and cyclohexyl-di-n-hexylphosphine. These compounds can also serve as allophanatization reaction catalysts. In addition, many of these compounds simultaneously promote the isocyanuration reaction, and in addition to uretdione group-containing polyisocyanates such as uretdione dimers, isocyanurate group-containing polyisocyanates such as isocyanurate trimers are produced.

  The polyisocyanate component having a uretdione group can also be obtained by heating without using a uretdione reaction catalyst. The uretdione group-containing polyisocyanate such as a uretdione dimer used in the present invention is preferably produced by heating from the viewpoint of storage stability.

  Furthermore, you may add another polyisocyanate which consists of a diisocyanate or more of diisocyanate to the said polyisocyanate component in arbitrary ratios. The bonding group constituting the other polyisocyanate is not particularly limited as long as the final polyisocyanate composition contains a biuret group.

B agent The polyurethane resin composition for electrical insulation of this invention contains B agent containing a polyol component.

Polyol Component The polyol component is not particularly limited, and various types of conventional polyol components can be used. As the polyol component, for example, a polyol having a hydroxyl group at the terminal represented by the following general formula (1) can be used.

(In the formula, R ₄ is a C 3-20 linear or branched, saturated or unsaturated, divalent hydrocarbon group which may have a hydroxyl group, and m is , Represents an integer of 1 to 20.)

  As the polyol represented by the general formula (1) having a hydroxyl group at the terminal, polybutadiene polyol is more preferably used. Examples of the polybutadiene polyol include polybutadiene polyol having 1,4 bonds of 60 mol% or more, preferably 80 mol% or more. The polybutadiene polyol has, for example, a repeating unit composed of polybutadiene having 60 to 90 mol% of 1,4 bonds and 10 to 40 mol% of 1,2 bonds, and the number of repetitions is 10 to 14. And polyols having hydroxyl groups at both ends.

  The molecular weight of the polybutadiene polyol is preferably 800 to 4800, and more preferably 1200 to 3000.

  Specific examples of the polyol component include polybutadiene polyol, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 2methyl 1,3-propanediol, 1,4-butanediol, 1,3 -Butanediol, 1,4-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,2-hexanediol, 2,5-hexanediol, octanediol, nonanediol Decanediol, diethylene glycol, triethylene glycol, dipropylene glycol, cyclohexanediol, trimethylolpropane, glycerin, 2-methylpropane-1,2,3-triol, 1,2,6-hexanetriol, pentaerythrit, poly Lactone geo Hydrogen, polylactone triol, ester glycol, polyester polyol, polyether polyol, polycarbonate polyol, acrylic polyol, silicone polyol, fluorine polyol, polytetramethylene glycol, polypropylene glycol, polyethylene glycol, polycaprolactone polyol, hydroxyl-containing liquid polyisoprene And hydrides of liquid polybutadiene containing hydroxyl groups.

As the polyol component, a castor oil-based polyol can be used. Examples of the castor oil-based polyol include castor oil or castor oil derivatives.
Castor oil fatty acid: castor oil fatty acid; castor oil or hydrogenated castor oil hydrogenated to castor oil fatty acid; transesterification product of castor oil and other fats and oils; reaction product of castor oil and polyhydric alcohol; esterification of castor oil fatty acid and polyhydric alcohol Reaction products: those obtained by addition polymerization of alkylene oxides.
As the castor oil-based polyol, castor oil is preferably used.

  The polyol component preferably contains at least one polyol selected from the polyol represented by the general formula (1) and a castor oil-based polyol. Moreover, it is preferable that the said polyol component contains at least 1 sort (s) of polyol selected from the polybutadiene polyol which has a 1, 4 bond 80 mol% or more, and a castor oil-type polyol.

  More preferably, the polyol component contains a polybutadiene polyol and a castor oil-based polyol. In this case, the compounding ratio of the polybutadiene polyol and the castor oil-based polyol is such that the total amount of the polybutadiene polyol and the castor oil-based polyol is 100% by mass, (polybutadiene polyol) :( castor oil-based polyol) = 90: 10% by mass to 50: It is preferably 50% by mass, and more preferably 90: 10% by mass to 70: 30% by mass. When the polyol component having the above blending ratio is used, the compatibility with the polyisocyanate component is excellent, the viscosity of the polyurethane resin composition for electrical insulation is lowered, and the workability is excellent.

  More preferably, the polyol component includes polybutadiene polyol and castor oil.

  More specifically, the polyol component used preferably is a hydroxyl group-containing liquid polybutadiene (hydroxyl group content = 1.83 mol / kg, viscosity = 1500 mPa · s (manufactured by Idemitsu Kosan Chemical Co., Ltd.) as a polyol having a hydroxyl group at the terminal. 30 ° C.), trade name: Poly bd (registered trademark) R-15HT, 1,4 bond: 80 mol%), and castor oil manufactured by Ito Oil Co., Ltd. (viscosity = 690 mPa · s (25 ° C.)) : Castor oil), and a polyol component obtained by mixing them.

  The equivalent ratio NCO / OH between the hydroxyl group (OH) of the polyol component and the isocyanate group (NCO) of the polyisocyanate component is preferably 0.70 to 1.40. By setting the equivalent ratio NCO / OH in the above range, a function as a moisture-proof insulating agent can be exhibited. The equivalent ratio NCO / OH is more preferably 0.80 to 1.20, and still more preferably 0.85 to 1.05.

(Other ingredients)
The polyurethane resin composition for electrical insulation of the present invention may contain a plasticizer in addition to the polyisocyanate component and the polyol component described above.
It does not specifically limit as said plasticizer, A conventionally well-known thing can be used. As the plasticizer, it is preferable to use a plasticizer having no hydroxyl group from the viewpoint of imparting elasticity to the cured product and reducing the viscosity at the time of preparing the composition. Such plasticizers include phthalates such as dioctyl phthalate, diisononyl phthalate, diundecyl phthalate, trimellitate plasticizers such as triethylhexyl trimellitate, triisodecyl trimellitate, tricresyl phosphate, trisoxy Examples thereof include phosphate esters such as rhenyl phosphate, cresyl diphenyl phosphate, xylenyl phosphate, triphenyl phosphate.

  The plasticizer may be contained in either agent A or agent B, but is preferably contained in agent B.

  In order not to inhibit the adhesiveness, heat resistance, moisture resistance, and insulation of the polyurethane resin composition for electrical insulation of the present invention, the content of the plasticizer is 100 masses of the total of the polyisocyanate component and the polyol component. It is preferable that it is 1-50 mass parts as a part. By making content of a plasticizer into the said range, the compatibility of the polyurethane resin composition for electrical insulation is excellent, and stickiness of a resin cured material can be suppressed. Moreover, when there is too much content of a plasticizer, there exists a possibility that the insulation of a resin cured material and moisture resistance may fall.

  The polyurethane resin composition for electrical insulation of the present invention may further contain other additives. Other additives include low molecular weight polyols for improving physical properties (such as bisphenol polyols, aniline polyols, hydrocarbon low molecular weight polyols such as octanediol), polymerization catalysts, viscosity modifiers (phthalic acid / fatty acid plasticizers, Process oils, silicone oils, paraffinic oligomers, olefinic oligomers, etc.), inorganic and organic fillers, anti-aging agents, antioxidants, stabilizers such as UV absorbers, flame retardants (phosphorus, halogen, antimony oxide) , Foam inhibitors, surface treatment agents, curing catalysts (such as tin-based, imidazole-based, and amine-based).

The total amount of the above other additives is 100 mass of the total of the polyisocyanate component and the polyol component in order not to inhibit the adhesion, heat resistance, moisture resistance, and insulation of the polyurethane resin composition for electrical insulation of the present invention. It is preferable that it is 0.1-10.0 mass parts as a part. It is more preferable that it is 0.1-5.0 mass parts at the point which can demonstrate heat resistance, moisture resistance, and insulation more.
Although the said other additive may be contained in any of A agent or B agent, it is preferable to be contained in B agent.

Since the polyurethane resin composition for electrical insulation described above is excellent in adhesion, heat resistance, moisture resistance, and insulation, it is useful as a sealing material for electrical components.
In addition, a resin-sealed electrical component can be manufactured using the sealing material. An electrical component resin-sealed using the sealing material is excellent in product stability, heat resistance, moisture resistance, and insulation.

  As a method of manufacturing the electrical component, the polyurethane resin composition for electrical insulation is injected and applied to a desired location of an adherend such as an electrical substrate, and is, for example, 30 to 90 at a temperature of 60 to 80 ° C. The method of heating for a minute is mentioned.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

(Synthesis example)
Below, the synthesis example of a polyisocyanate component is shown. For the synthesized polyisocyanate component, the viscosity, NCO group content, and the molar ratio of biuret group, uretdione group, and isocyanurate group were measured by the following methods.

<Viscosity of polyisocyanate component>
The viscosity at 25 ° C. of the polyisocyanate component was measured using an E-type viscometer RE-85R (manufactured by Toki Sangyo Co., Ltd.). The rotor used was a standard rotor (1 ° 34 ′ × R24). The number of rotations was as follows.
100r. p. m. (If less than 128 mPa · s)
50r. p. m. (In the case of 128 mPa · s or more and less than 256 mPa · s)
20r. p. m. (In the case of 256 mPa · s or more and less than 640 mPa · s)
10r. p. m. (In the case of 640 mPa · s or more and less than 1,280 mPa · s)
5r. p. m. (In the case of 1,280 mPa · s or more and less than 2,560 mPa · s)
2.5r. p. m. (In the case of 2,560 mPa · s or more and less than 5,120 mPa · s)
1.0r. p. m. (In the case of 5,120 mPa · s or more and less than 12,800 mPa · s)
0.5r. p. m. (In the case of 12,800 mPa · s or more and less than 25,600 mPa · s)

<NCO group content of polyisocyanate component>
2 to 3 g of the polyisocyanate component was dissolved in 20 mL of toluene, 20 mL of 2N di-n-butylamine toluene solution was added and mixed, and the mixture was allowed to stand for 15 minutes. 70 ml of isopropanol was added and back titrated with 1N hydrochloric acid. The NCO group content (mass%) of the polyisocyanate component was measured from the result of this back titration.

<Molar ratio of biuret group, uretdione group, and isocyanurate group>
The molar ratio of biuret group and uretdione group in the polyisocyanate component obtained in the synthesis example and in the polyisocyanate obtained in the examples was measured by 13C-NMR (manufactured by Bruker, FT-NMRDPX-400).

An example of a method for measuring polyisocyanate using HDI as a raw material by 13 C-NMR is shown below.
Measurement method example of 13C-NMR: The polyisocyanate component prepared in Synthesis Examples 1 to 7 was dissolved in deuterium chloroform at a concentration of 10% by mass. As a chemical shift standard, the carbon atom signal of deuterium chloroform was 77.0 ppm. The area of the carbon atom signal of the biuret group near 156.4 ppm and the area of the carbon atom signal of the uretdione group near 157.8 ppm were measured. Based on the obtained area, the molar ratio of biuret group and uretdione group in the polyisocyanate component and in the blocked isocyanate composition was calculated by the following formula.
(Biuret group / uretdione group) = (signal area around 156.4 ppm / 2) / (signal area around 157.8 ppm / 2)

Furthermore, the signal area of the carbon atom of the isocyanurate group around 149.0 ppm was measured. Based on the obtained area, the molar ratio of biuret group, uretdione group and isocyanurate group in the polyisocyanate component was calculated by the following formula.
(Biuret group / uretdione group / isocyanurate group) = (signal area around 156.4 ppm / 2) / (signal area around 157.8 ppm / 2) / (signal area around 149.0 ppm / 3)

Synthesis example 1
(Synthesis of polyisocyanate component A-1)
After making the inside of the flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen blowing tube into a nitrogen atmosphere, HDI: 700 parts by mass, trimethyl phosphoric acid: 150 parts by mass, methyl cellosolve acetate: 150 parts by mass, and water: 12 .5 parts by mass (HDI / water molar ratio = 6) was charged, and the liquid temperature was maintained at 160 ° C. for 1 hour. Polyisocyanate component A-1 was obtained by feeding the obtained reaction liquid to a thin film distiller. The obtained polyisocyanate component A-1 had a viscosity at 25 ° C. of 9700 mPa · s and an isocyanate group (NCO group) content of 21.5%. Moreover, when polyisocyanate component A-1 measured 13C-NMR, biuret group / uretdione group (molar ratio) was 95/5.

Synthesis example 2
(Synthesis of polyisocyanate component A-2)
In Synthesis Example 1, synthesis was performed in the same manner as in Synthesis Example 1 except that the amount of water charged was 4.2 parts by mass (HDI / water molar ratio = 18) to obtain polyisocyanate component A-2. The obtained polyisocyanate component A-2 had a viscosity at 25 ° C. of 2300 mPa · s and an isocyanate group (NCO group) content of 23.3%. Moreover, when the polyisocyanate component A-2 measured 13C-NMR, biuret group / uretdione group (molar ratio) was 90/10.

Synthesis example 3
(Synthesis of polyisocyanate component A-3)
In Synthesis Example 1, synthesis was performed in the same manner as in Synthesis Example 1 except that the amount of water charged was 1.5 parts by mass (HDI / water molar ratio = 50) to obtain polyisocyanate component A-3. The obtained polyisocyanate component A-3 had a viscosity at 25 ° C. of 360 mPa · s and an isocyanate group (NCO group) content of 23.9%. Moreover, when the polyisocyanate component A-3 was measured by 13 C-NMR, the biuret group / uretodione group (molar ratio) was 75/25.

Synthesis example 4
(Synthesis of polyisocyanate component A-4)
In Synthesis Example 1, synthesis was performed in the same manner as in Synthesis Example 1 except that the amount of water charged was 0.9 parts by mass (HDI / water molar ratio = 83) to obtain polyisocyanate component A-5. The obtained polyisocyanate component A-4 had a viscosity at 25 ° C. of 120 mPa · s and an isocyanate group (NCO group) content of 24.1%. Moreover, as for polyisocyanate component A-4, when 13 C-NMR was measured, biuret group / uretdione group (molar ratio) was 60/40.

Synthesis example 5
(Synthesis of polyisocyanate component A-5)
In Synthesis Example 1, synthesis was performed in the same manner as in Synthesis Example 1 except that the amount of water charged was 0.6 parts by mass (HDI / water molar ratio = 120) to obtain polyisocyanate component A-5. The obtained polyisocyanate component A-6 had a viscosity at 25 ° C. of 20 mPa · s and an isocyanate group (NCO group) content of 24.3%. Moreover, when polyisocyanate component A-5 measured 13C-NMR, biuret group / uretdione group (molar ratio) was 40/60.

Synthesis Example 6
(Synthesis of polyisocyanate component A-6)
In the same apparatus as in Synthesis Example 1, 1000 g of HDI was charged, and the temperature in the reactor was kept at 60 ° C. with stirring. Then, 2.1 g of tetramethylammonium acetate (2-butanol 5.0% by mass solution) was added as an isocyanuration reaction catalyst to carry out the reaction. After 4 hours, the reaction end point was confirmed by measuring the refractive index of the reaction solution, and 0.2 g of phosphoric acid (85 mass% aqueous solution) was added to stop the reaction. After filtering the reaction solution, unreacted HDI was removed using a thin film distillation apparatus to obtain polyisocyanate component A-6 having an isocyanurate group. The obtained polyisocyanate component A-6 had a viscosity at 25 ° C. of 2,500 mPa · s and an isocyanate group (NCO group) content of 22.2% by mass.

Synthesis example 7
(Synthesis of polyisocyanate component A-7)
100 parts by mass of the polyisocyanate component A-2 synthesized in Synthesis Example 2 and 21.1 parts by mass of the polyisocyanate A-6 synthesized in Synthesis Example 6 were collected in the same apparatus as in Synthesis Example 1, 40 The mixture was mixed at 0 ° C. to obtain polyisocyanate component A-7. The obtained polyisocyanate component A-7 had a viscosity at 25 ° C. of 2,300 mPa · s and an isocyanate group (NCO group) content of 23.0% by mass. Moreover, when 13 C-NMR was measured, it was found that the biuret group / uretdione group / isocyanurate group (molar ratio) was 72/8/20. The biuret group / uretdione group (molar ratio) was 90/10.

Example 1
As a polyol having a hydroxyl group at the end, a product name: Poly bd (registered trademark) R-15HT manufactured by Idemitsu Kosan Co., Ltd., which is a polybutadiene polyol having an average hydroxyl value of 103 mgKOH / g, was prepared. Furthermore, dioctyltin dilaurate (trade name: Neostan U-810, manufactured by Nitto Kasei Co., Ltd.) was prepared as a polymerization catalyst.
These were charged into a reaction kettle equipped with a heating, cooling, and decompression device at the blending amounts shown in Table 1, dehydrated at 100 ° C. under a pressure of 10 mmHg or less for 2 hours, and a polyol component (B agent) and did.

  As the polyisocyanate component, the polyisocyanate component A-1 synthesized in Synthesis Example 1 was prepared and used as A agent.

  A polyurethane resin composition for electrical insulation was obtained by adding the A agent to the B agent and stirring and defoaming in the blending amounts shown in Table 1. In addition, the compounding ratio of A agent and B agent was prepared so that the active hydrogen in a polyol component might be 1 equivalent with respect to 1 equivalent of isocyanate groups in a polyisocyanate component.

(Production of test piece)
The electrically insulating polyurethane resin composition obtained as described above was poured into a molding die having a size of 130 × 130 × 3 mm and a molding die having an inner diameter of 30 mm and a height of 10 mm. When the polyurethane resin composition for electrical insulation was cured, the injected polyurethane resin composition for electrical insulation was heated at 60 ° C. for 16 hours and then allowed to stand at room temperature for 1 day to cure.

Examples 2-9, Comparative Examples 1-5
A polyurethane resin composition for electrical insulation was prepared in the same manner as in Example 1 except that the A agent was added to the B agent with the formulation shown in Table 1. Of the raw materials used in these Examples and Comparative Examples, the raw materials other than the raw materials used in Example 1 are as follows.
Castor oil: castor oil (trade name: castor oil, manufactured by Ito Oil Co., Ltd.)
-TPA-100: Hexamethylene diisocyanate (HDI) -based isocyanate (trade name: Duranate TPA-100, manufactured by Asahi Kasei Chemicals Corporation)
MTL: Diphenylmethane diisocyanate (MDI) isocyanate (trade name: Millionate MTL, manufactured by Tosoh Corporation)

  The characteristics were evaluated by the following evaluation methods using the polyurethane resin compositions prepared according to the above-described Examples and Comparative Examples, and test pieces prepared using the polyurethane resin compositions.

(Adhesion evaluation)
A polyurethane resin composition was applied to the surface of an adherend made of polyphenylene sulfide resin (PPS) in an area of 25 mm × 12.5 mm, and the adhesive strength was measured by a measuring method based on JIS K6850. Based on the measurement results, adhesion was evaluated according to the following evaluation criteria.
○: Adhesive strength is 5 MPa or more Δ: Adhesive strength is 4 MPa or more and less than 5 MPa X: Adhesive strength is less than 4 MPa

(Initial hardness)
Using the test pieces prepared according to the above-described examples and comparative examples, the measurement was performed using a type A hardness meter in accordance with JIS K6253.

(Heat resistance evaluation (hardness after heat resistance test))
Using the test pieces produced according to the above-described examples and comparative examples, the test pieces were allowed to stand for 500 hours under a temperature condition of 100 ° C., and then the type A hardness was measured according to JIS K6253. Based on the rate of change in hardness from the initial hardness, heat resistance was evaluated according to the following evaluation criteria.
○: Hardness change rate from initial hardness is 20% or less Δ: Hardness change rate from initial hardness is more than 20 and 30% or less ×: Hardness change rate from initial hardness is more than 30%

(Moisture resistance evaluation (hardness after moisture resistance test))
The test pieces prepared according to the above-described examples and comparative examples were treated with a pressure cooker at 121 ° C. and 100% RH for 100 hours, and then the type A hardness was measured according to JIS K6253. Based on the rate of change in hardness from the initial hardness, moisture resistance was evaluated according to the following evaluation criteria.
○: Hardness change rate from initial hardness is 50% or less Δ: Hardness change rate from initial hardness is more than 50% and 80% or less ×: Hardness change rate from initial hardness is more than 80%

(Insulation evaluation)
The volume resistivity at 23 ° C. of the test pieces produced according to the above examples and comparative examples was measured. Based on the measurement results, the insulation was evaluated according to the following evaluation criteria.
○: Volume resistivity is 1.0 × 10 ¹⁰ Ω · m or more ×: Volume resistivity is less than 1.0 × 10 ¹⁰ Ω · m

  The evaluation results of the above evaluation are shown in Table 1.

Claims (7)

(1) A agent containing a polyisocyanate component obtained from at least one selected from an aliphatic diisocyanate and an alicyclic diisocyanate and containing a biuret group and a uretdione group ;
(2) A polyurethane resin composition for electrical insulation comprising a B agent containing a polyol component. Before Symbol molar ratio of biuret groups of the polyisocyanate component (a) and uretdione groups (b) (a) / ( b) is a 95 / 5-60 / 40, polyurethane for electrical insulation according to claim 1 Resin composition. Wherein the molar ratio of biuret groups of the polyisocyanate component (a) and uretdione groups (b) (a) / ( b) is 95 / 5-70 / 30 are, for electrical insulation polyurethane resin according to claim 1 Composition. The polyol component has the following general formula (1):

(In the formula, R ₄ is a C 3-20 linear or branched divalent unsaturated aliphatic hydrocarbon group which may have a hydroxyl group, and m is 1-20. The polyurethane resin composition for electrical insulation according to any one of claims 1 to 3, comprising at least one polyol selected from a polyol represented by (2) and a castor oil-based polyol.   5. The polyurethane resin for electrical insulation according to claim 1, wherein the polyol component includes at least one polyol selected from polybutadiene polyol having 1,4 bonds of 60 mol% or more and castor oil-based polyol. Composition.   The sealing material which consists of a polyurethane resin composition for electrical insulation in any one of Claims 1-5.   An electrical component sealed with a resin using the sealing material according to claim 6.