JP2007332279A - One pack type moisture-curable coating agent, electric/electronic component insulated with the same agent and method for producing the same component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide one pack type curable coating agent excellent in moisture-proof insulating property and workability of electric/electronic components and electric/electronic components having high reliability, insulated with the coating agent and to provide a method for producing these components. <P>SOLUTION: The one pack type moisture-proof curable coating agent is obtained by reacting (a) an organic polyisocyanate with (b) a polycarbonate diol having 500-3,000 number-average molecular weight and (c) a polyester polyol containing a diol monomer having 6-12C alkylene group as a unit so that NCO/OH ratio of (a)/[(b)+(c)] becomes 1.8-2.3. The method for producing the electronic components comprises using the one pack type moisture-curable coating agent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a one-component moisture-curing coating agent excellent in moisture-proof insulating properties and workability for the purpose of moisture-proofing electrical / electronic components, and an insulated electrical / electronic component and a method for producing the same.

Recent electrical and electronic components are becoming smaller, lighter and higher in performance, and the mounting circuit boards used for various electrical and electronic components are mounted with high density to protect them from moisture, dust, etc. acrylic resin, silicone Protective coating with resin paint and casting sealing with urethane resin, epoxy resin, etc. are performed. Such a mounting circuit board is used in a severe environment, particularly at a high humidity, and is used by being mounted on a device such as a washing machine, an automobile, or a flat panel display.
However, the paint cannot completely protect the pin foot of the electronic component mounted on the mounting circuit board, resulting in a problem that the moisture resistance is inferior, and in the case of the silicone resin paint, it takes time to cure and there is a problem in productivity. there were.
On the other hand, urethane resin and epoxy resin used for casting treatment have excellent insulation and moisture and heat resistance, but when left for a long time under high temperature conditions, the cured product becomes hard due to oxidative degradation, and components and mounting circuits When stress is applied to a plate or the like, cracks and peeling occur, which may reduce reliability.

JP-A-11-49947 JP 2003-335936 A

  The present invention solves the above-mentioned problems of the prior art, is suitable for moisture-proof insulation and the like, and further, a one-component moisture-curing coating agent capable of forming a cured product excellent in workability, and a highly reliable electrical insulation treatment. -It aims at providing an electronic component and its manufacturing method.

The present invention provides [1] (a) an organic polyisocyanate, (b) a polycarbonate diol having a number average molecular weight of 500 to 3000, and (c) a number average having a diol monomer having an alkylene group having 6 to 12 carbon atoms as a structural unit. One-part moisture curable coating obtained by reacting a polyester polyol having a molecular weight of 1000 to 5000 so that the NCO / OH ratio of (a) / [(b) + (c)] is 1.8 to 2.3. It is an agent.
Further, the present invention is as described in [1] above, wherein [2] (b) polycarbonate diol and (c) polyester polyol have a hydroxyl group molar ratio ((b) / (c)) of 95/5 to 80/20. This is a one-component moisture-curing coating agent.
Furthermore, the present invention is [3] an electrical / electronic component that is insulated using the one-component moisture-curing coating agent described in [1] or [2].
Further, according to the present invention, [4] the one-component moisture-curing coating agent described in [1] or [2] is applied to an electric / electronic component and cured, and then the insulating treatment described in [3] is performed. This is a method for manufacturing electrical and electronic parts.

  The one-component moisture curable coating agent of the present invention is excellent in workability and can provide various highly reliable electric / electronic parts subjected to insulation treatment.

  As the organic polyisocyanate which is the component (a) used in the present invention, polyisocyanates such as diisocyanate compounds, triisocyanate compounds and tetraisocyanate compounds can be used. For example, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, diphenylsulfone diisocyanate, triphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 3-isocyanate ethyl-3 , 5,5-trimethylcyclohexyl isocyanate, 3-isocyanatoethyl-3,5,5-triethylcyclohexyl isocyanate, diphenylpropane diisocyanate, phenylene diisocyanate, cyclohexylylene diisocyanate, 3,3'-diisocyanate dipropyl ether, triphenylmethane triisocyanate , Diphenyl ether , 4'-diisocyanate, methylenebis (4-cyclohexyl isocyanate), polyisocyanates include such isophorone diisocyanate, it may be used in combination of these alone, or two or more.

The polycarbonate diol composed of the number average molecular weight 500 to 3000 of the component (b) used in the present invention can be obtained, for example, by reacting a carbonate compound and a diol. As the carbonate compound, dimethyl carbonate, diphenyl carbonate, ethylene carbonate and the like can be used.
Diols include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol, and other aliphatic diols, cyclohexanediol, and hydrogenated xylylene. One or a mixture of two or more of alicyclic diols such as length reels and aromatic diols such as xylylene glycol are used, among which aliphatic diols, especially butanediol, methylpentanediol, hexanediol, heptanediol, Suitable examples include one or a mixture of two or more aliphatic diols having a carbon chain length of 4 to 9, such as methyloctanediol and nonanediol. The number average molecular weight of the carbonate diol needs to be 500 to 3000. If this value is less than 500, the adhesion to the circuit board is poor, and if it exceeds 3000, the viscosity of the coating agent becomes high and the workability decreases.

The polyester polyol having a number average molecular weight of 1000 to 5000 having a diol monomer having an alkylene group having 6 to 12 carbon atoms as the component (c) used in the present invention is obtained, for example, by reacting a dibasic acid with a diol. be able to.
Dibasic acids include aliphatic dibasic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, and brassylic acid, and aromatic dibasic acids such as isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. One kind of basic acid or a combination thereof can be used. Of these, dibasic acids having a methylene chain length of 3 to 8 such as glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, and sebacic acid are more preferably used.
As the diol, it is necessary to use a diol monomer having an alkylene group having 6 to 12 carbon atoms, preferably 8 to 12 carbon atoms. Examples of such monomers include methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, and dodecanediol. If the alkylene group has less than 6 carbon atoms, it will be difficult to crystallize and the solidification time will be longer. On the other hand, when this value exceeds 12, the workability and the adhesion to the coating material are lowered due to the increase in viscosity. Examples of other diol monomers include aliphatic diols such as ethylene glycol, propylene glycol, butanediol and neopentyl glycol, which may be substituted with lower alcohols, cycloaliphatic diols such as hydrogenated xylylene glycol, One or a mixture of two or more aromatic diols such as xylylene glycol is used. The number average molecular weight of the polyester polyol needs to be 1000 to 5000. If this value is less than 1000, it is difficult to crystallize and the solidification time becomes long, and if it exceeds 5000, the viscosity of the coating agent increases and the workability decreases.

In the present invention, the NCO / OH ratio ((a) / [(b) + (c)]) of the organic polyisocyanate compound as the component (a) and the polyol mixture as the component (b) + (c) is 1.8 to It is determined to be in the range of 2.3. If it is less than 1.8, the viscosity of the resulting prepolymer becomes too high, resulting in poor workability and poor heat stability during the coating operation. This is because when the ratio exceeds 2.3, the resulting coating film becomes brittle, and the moisture-proof insulating property is deteriorated.
Moreover, the hydroxyl group molar ratio of the polycarbonate diol and the polyester polyol in the polyol mixture is preferably 95/5 to 80/20 (polycarbonate diol / polyester polyol). If the ratio of the polyester polyol is less than 5, the solidification time becomes long, and if it exceeds 20 the moisture and heat resistance is lowered.
In order to obtain a prepolymer from the above organic polyisocyanate compound and polyol mixture, a heat and defoaming mixer is used and several air is shut off by purging nitrogen gas in the range of 50 to 130 ° C. Heat and react for hours.

  In the present invention, a thermoplastic polymer (polyurethane, ethylene copolymer, propylene copolymer, vinyl chloride copolymer, acrylic copolymer, styrene-conjugated diene block copolymer, etc.) is optionally selected. Rubber type), tackifying resin (rosin resin, rosin ester resin, hydrogenated rosin ester resin, terpene resin, terpene phenol resin, hydrogenated terpene resin, petroleum resin, hydrogenated petroleum resin, coumarone resin, ketone resin, styrene resin, Modified resins such as modified styrene resins, xylene resins, epoxy resins), catalysts (dibutyltin dilaurate, dibutyltin dioctate, dimethylcyclohexylamine, dimethylbenzylamine, trioctylamine, etc.), pigments or dyes, antioxidants, Appropriate amounts of UV absorbers, surfactants, flame retardants, fillers, etc. It may be.

  Examples of the electrical / electronic components insulated using the one-component moisture curable coating agent according to the present invention include a microcomputer, a transistor, a capacitor, a resistor, a relay, a transformer, and a mounting circuit board on which these are mounted. Lead wires, harnesses, film substrates and the like joined to these electric / electronic components can also be included. Moreover, the signal input part of flat panel display panels, such as a liquid crystal display panel, a plasma display panel, an organic electroluminescent panel, a field emission display panel, etc. are mentioned.

  Examples of the method for producing an electrical / electronic component insulated using the one-component moisture-curing coating agent according to the present invention include, for example, heating and melting the one-component moisture-curing coating agent on the electrical / electronic component. After being applied to the substrate and solidified by cooling, it may be cured by moisture in the air.

  The present invention will be described more specifically with reference to the following examples and comparative examples. The results of these specific examples are shown in Table 1, but the present invention is not limited thereto.

Example 1
Polycarbonate diol (N-980, manufactured by Nippon Polyurethane Industry Co., Ltd., number of functional groups: 2.0, number average molecular weight: 2000) mainly composed of 1,6 hexanediol, which has been dehydrated in advance by a vacuum dryer, sebacic acid and 1,6- 100 parts by weight of a polyol component having a hydroxyl group molar ratio of 90/10 and diphenylmethane diisocyanate of a polyester polyol (Hitachi Kasei Polymer Co., Ltd. A-48, functional group number 2.0, number average molecular weight 5000) made mainly of hexanediol 22.3 parts by weight (NCO / OH ratio is 2.05) was charged into a reaction vessel capable of being heated and defoamed and stirred, and mixed and stirred in a nitrogen gas atmosphere for 2 hours at 110 ° C. Defoaming and stirring under reduced pressure at 110 ° C. for 2 hours gave a polyurethane prepolymer (viscosity: 7.0 Pa · s / 120 ° C.). .

(Example 2)
Polycarbonate diol (N-982, manufactured by Nippon Polyurethane Industry Co., Ltd., functional group number 2.0, number average molecular weight 2000), which is dehydrated in advance by a vacuum dryer, and 1,6-hexanediol as main components, sebacic acid and 1 100 parts by weight of a polyol component having a hydroxyl group molar ratio of 80/20 of a polyester polyol (A-48 manufactured by Hitachi Chemical Polymer Co., Ltd., functional group number 2.0, number average molecular weight 5000), which is mainly composed of 6 hexanediol, After putting 19.7 parts by weight of diphenylmethane diisocyanate (NCO / OH ratio is 2.05) into a reaction vessel capable of being heated and defoamed and stirred for 2 hours at 110 ° C. with mixing and stirring in a nitrogen gas atmosphere. Further, the mixture was stirred under reduced pressure at 110 ° C. for 2 hours under reduced pressure to give a polyurethane prepolymer (viscosity: 6.0 Pa · s). To obtain a 120 ℃).

(Comparative Example 1)
100 parts by weight of polycarbonate diol (N-980, manufactured by Nippon Polyurethane Industry Co., Ltd., functional group number 2.0, number average molecular weight 1000) mainly composed of 1,6-hexanediol dehydrated in advance by a vacuum dryer and 25 diphenylmethane diisocyanate .6 parts by weight (NCO / OH ratio is 2.05) was charged into a reaction vessel capable of being heated and degassed and stirred and reacted at 110 ° C. for 2 hours with mixing and stirring in a nitrogen gas atmosphere. Defoaming and stirring under reduced pressure at 2 ° C. for 2 hours gave a polyurethane prepolymer (viscosity: 2.0 Pa · s / 120 ° C.).

(Comparative Example 2)
Polyester polyol (A-48 manufactured by Hitachi Chemical Co., Ltd., functional group number 2.0, number average molecular weight 5000) and adipic acid, which are mainly composed of sebacic acid and 1,6-hexanediol when dehydrated in advance by a vacuum dryer Polyol component 100 having a hydroxyl group mole ratio of 85/15 of polyester polyol (A-43, manufactured by Hitachi Chemical Polymer Co., Ltd., functional group number 2.0, number average molecular weight 5000) mainly composed of 1,6-hexanediol Part by weight and 10.3 parts by weight of diphenylmethane diisocyanate (NCO / OH ratio is 2.05) are placed in a reaction vessel capable of heating and defoaming and stirring, and the reaction is carried out at 110 ° C. for 2 hours while mixing and stirring in a nitrogen gas atmosphere. And then defoaming and stirring under reduced pressure at 110 ° C. for 2 hours to produce a polyurethane prepolymer (viscosity: 20.0 Pa · s / 12). ℃) was obtained.

(Comparative Example 3)
Polycarbonate diol (N-980, manufactured by Nippon Polyurethane Industry Co., Ltd., number of functional groups: 2.0, number average molecular weight: 2000) mainly composed of 1,6 hexanediol, which has been dehydrated in advance by a vacuum dryer, sebacic acid and 1,6- 100 parts by weight of a polyol component having a hydroxyl group molar ratio of 90/10 and diphenylmethane diisocyanate of a polyester polyol (Hitachi Kasei Polymer Co., Ltd. A-48, functional group number 2.0, number average molecular weight 5000) made mainly of hexanediol 17.4 parts by weight (NCO / OH ratio is 1.60) was charged into a reaction vessel capable of heating and defoaming and stirred for 2 hours at 110 ° C. with mixing and stirring in a nitrogen gas atmosphere. Defoaming and stirring under reduced pressure at 110 ° C. for 2 hours, polyurethane prepolymer (viscosity: 24.0 Pa · s / 120 ° C.) It was.

(Comparative Example 4)
Polycarbonate diol (N-980, manufactured by Nippon Polyurethane Industry Co., Ltd., number of functional groups: 2.0, number average molecular weight: 2000) mainly composed of 1,6 hexanediol, which has been dehydrated in advance by a vacuum dryer, sebacic acid and 1,6- 100 parts by weight of a polyol component having a hydroxyl group molar ratio of 90/10 and diphenylmethane diisocyanate of a polyester polyol (Hitachi Kasei Polymer Co., Ltd. A-48, functional group number 2.0, number average molecular weight 5000) made mainly of hexanediol 27.1 parts by weight (NCO / OH ratio is 2.50) was placed in a reaction vessel capable of being heated and degassed and stirred and reacted at 110 ° C. for 2 hours with mixing and stirring in a nitrogen gas atmosphere. Defoaming and stirring under reduced pressure at 110 ° C. for 2 hours gave a polyurethane prepolymer (viscosity: 2.0 Pa · s / 120 ° C.). .

  The following tests were conducted using the one-part moisture curable coating agent of the present invention obtained in Examples 1 and 2 and the one-part moisture curable coating agent obtained in Comparative Examples 1 to 4.

(Solidification time)
Apply the above one-component moisture-curing coating agent on a PET sheet (thickness: 30 μm) in a 20 ° C. atmosphere at 120 ° C. for 1-2 hours with a spatula in a bead shape (width: about 2 mm × height: about 2 mm) Then, the time until the coating agent did not adhere to the finger when allowed to stand and the time when no deformation was observed even when the coating agent was pressed with the finger were measured as the solidification time.

(Moisture and heat resistance)
A piece of tin plate (size: 50 mm x 180 mm x 0.25 mm) with 3 layers of polyester tape (width: 10 mm, thickness: about 50 μm) was prepared and left at 120 ° C for 1-2 hours. The liquid moisture curable coating agent was applied with a glass rod while adjusting the thickness to be about 100 to 150 μm, and allowed to stand at room temperature (25 ° C.) for 24 hours to obtain a test piece. This test piece was placed vertically in a constant temperature and humidity chamber at 90 ° C. and 85% RH, and the state of the coating agent was observed and evaluated. Evaluation was made as “◯” for those that were not softened, “Δ” for those that were slightly softened, and “X” for those that were softened.

(Heat-resistant)
A piece of tin plate (size: 50 mm x 180 mm x 0.25 mm) with 3 layers of polyester tape (width: 10 mm, thickness: about 50 μm) was prepared and left at 120 ° C for 1-2 hours. A liquid moisture curable coating agent was applied with a glass rod while adjusting the thickness to be about 100 to 150 μm, and allowed to stand at room temperature for 24 hours to obtain a test piece. This test piece was placed vertically in a hot air circulating dryer at 125 ° C. to evaluate the dripping of the coating agent. The case where there was no dripping was evaluated as “◯”, the case where there was slight dripping was evaluated as “Δ”, and the case where there was dripping was evaluated as “×”.

(Moisture-proof insulation)
Using a glass Ag electrode comb substrate (100 μm between lines), a voltage of DC 60 V was applied to a test piece obtained by applying and curing a coating agent on a circuit board with a coating thickness of about 150 μm at 60 ° C. and 90% RH. The time until energization was measured. Those that were not energized until 500 hours were defined as 500 <.
These measurement results are summarized in Table 1.

From the results shown in Table 1, Comparative Example 1 using only polycarbonate diol has good heat and moisture resistance and moistureproof insulation, but has a long solidification time. Further, in Comparative Example 2 using only two types of polyester polyols, the solidification time is short and the curability is good, but the moisture and heat resistance and moisture proof insulation are poor. In contrast, Examples 1 and 2 in which the polycarbonate diol and the polyester polyol of the present invention are used in combination are excellent in solidification time, heat and moisture resistance, and moisture-proof insulating properties. Suitable for moisture-proof insulation of mounted circuit boards used for parts, and excellent workability.

Claims (4)

(A) Organic polyisocyanate, (b) Polycarbonate diol having a number average molecular weight of 500 to 3000, and (c) Polyester having a number average molecular weight of 1000 to 5000 having a diol monomer having an alkylene group having 6 to 12 carbon atoms as a structural unit. A one-component moisture-curable coating agent obtained by reacting a polyol such that the NCO / OH ratio of (a) / [(b) + (c)] is 1.8 to 2.3. The one-component moisture curable coating agent according to claim 1, wherein the hydroxyl group mole ratio ((b) / (c)) of (b) polycarbonate diol and (c) polyester polyol is 95/5 to 80/20. An electrical / electronic component that is insulated using the one-component moisture-curing coating agent according to claim 1. The method for producing an insulated electrical / electronic component according to claim 3, wherein the one-component moisture curable coating agent according to claim 1 or 2 is applied to an electrical / electronic component and cured.