JP2003246834A - One-part composition for insulating polyurethane resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-part composition for an insulating polyurethane resin which can be easily handled and yields an insulating cured product wherein the hardness is substantially unchanged and the insulation performance is substantially not reduced, even upon exposing to high temperatures or high- temperature/high-humidity conditions. <P>SOLUTION: The one-part composition for the insulating polyurethane resin comprises a urethane prepolymer obtained by allowing a polyisocyanate to react with a polyol having an oxygen content of ≤22 wt.% and an iodide value of ≤155 mg KOH/g. Here, the terminal isocyanate groups of the urethane prepolymer are blocked. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composition for one-pack type insulating polyurethane resin.

[0002]

Curing with excellent heat resistance (hardness and other physical properties do not change even when exposed to high temperature) and wet heat resistance (hardness and other physical properties that do not change even when exposed to high temperature and high humidity) As a polyurethane resin that can provide products, iodine value is 11
Oxygen atom content is 20 wt% at 0 mgKOH / g or less
There is a polyurethane resin obtained by reacting the following polyol and polyisocyanate, and the polyurethane resin is used as a filter seal material in a clean room of a food factory, a precision parts factory, a nuclear power plant, etc. 2001-270927). When a polyurethane resin having excellent heat resistance and moist heat resistance is used as an electrically insulating material, for example, as a sealant that protects an electric circuit from impact, dust, etc., heat generated by electricity flows in a cured product of the polyurethane resin. Even if it is trapped in a sheet or exposed to high temperature and high humidity by using it around water, the hardness of the cured product, which is adjusted to effectively protect the electric circuit from impact, hardly changes. Therefore, the electric circuit can be effectively protected from a shock.

[0003]

However, in order to use a polyurethane resin as an insulating material, it is not enough that the hardness of the cured product of the polyurethane resin used hardly changes even when exposed to high temperature or high temperature and high humidity. Enough
It is required that the cured product has an insulating property and that the hardness and the insulating property hardly decrease even when the insulating cured product is exposed to high temperature or high temperature and high humidity. In addition, in recent years, with the increasing demand for insulating polyurethane resins, it has become necessary to perform insulating work in various places or under conditions, and it has also been demanded that insulating materials be easily handled. Is coming.

The present invention can provide an insulative cured product whose hardness hardly changes even when exposed to high temperature or high temperature and high humidity, and its insulating property hardly deteriorates, and the one-component type insulation which is easy to handle. An object is to provide a composition for a hydrophilic polyurethane resin.

[0005]

Means for Solving the Problems In view of the above problems, the present inventor has conducted diligent research, and as a result, as a polyol constituting an insulating polyurethane resin, a polyol having an iodine value and an oxygen content rate adjusted to be equal to or lower than a certain value was selected. When used, the obtained cured product of the insulating polyurethane resin not only has little change in hardness even when exposed to high temperature or high temperature and high humidity,
The present invention has been completed by discovering that the insulating property also hardly deteriorates.

That is, according to the present invention, a urethane prepolymer obtained by reacting a polyol having an oxygen content of 22% by weight or less and an iodine value of 155 mgKOH / g or less with a polyisocyanate is contained. There is provided a composition for a one-pack type insulating polyurethane resin, characterized in that the terminal isocyanate group is blocked. When such a one-pack type insulating polyurethane resin composition is used as an insulating material for an electric circuit, the hardness and the hardness of the insulating cured material encapsulating the electric circuit can be improved even when exposed to high temperature or high temperature and high humidity. Insulation properties are hardly deteriorated together. Moreover, since the isocyanate group is blocked by the blocking agent, it is a one-pack type, and therefore one-pack type.
When forming an insulating cured product, like a two-part composition,
Physical properties such as hardness of the obtained insulating cured product can be determined at the stage of obtaining the composition for an insulating polyurethane resin without requiring equipment and labor for mixing the two liquids, and desired physical properties of the cured product can be obtained. Easy to handle, such as easy to obtain. Therefore, the composition can be used as it is even for difficult requirements, for example, when it is required to insulate a predetermined portion of a complicated electric circuit. Therefore, the work is relatively easy.

Further, according to the present invention, there is provided the above-mentioned composition for one-component insulating polyurethane resin for insulating electric or electronic parts.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyol used in the present invention has an oxygen content of 22% by weight or less and an iodine value of 155 mg.
KOH / g or less. Oxygen content of polyol is 22
When the content is more than 5% by weight, the obtained insulating cured product is inferior in wet heat resistance, the hardness is greatly reduced in a high temperature and high humidity state, and the insulation property is also deteriorated. On the other hand, when the iodine value exceeds 155 mgKOH / g, the heat resistance of the insulating cured product is poor and it becomes hard and brittle at high temperature. The oxygen content of the polyol is preferably 1
~ 15% by weight. When the oxygen content is in this range,
The wet heat resistance of the insulating cured product is particularly improved. The iodine value is preferably 1 to 120 mgKOH / g. When the iodine value is in this range, the heat resistance of the insulating cured product is particularly improved. Here, the oxygen content (% by weight) is

[0009]

[Formula 1]

It is calculated by Iodine value (mgKOH /
g) is measured according to JIS K 3331 ^-1995.

As the polyol to be used in the present invention, a polyester resin using a polyester polyol, a polyether resin using a polyether polyol, and other polyols are used as long as the obtained cured product exhibits insulating properties. Any resin or mixture of these can be used.

Polyester polyol is a reaction product of a fatty acid and a polyol, and examples of the fatty acid include:
Ricinoleic acid, oxycaproic acid, oxycapric acid,
Examples thereof include hydroxy-containing long-chain fatty acids such as oxyundecanoic acid, oxylinoleic acid, oxystearic acid, and oxyhexanedecenoic acid. Examples of polyols that react with fatty acids include ethylene glycol, propylene glycol,
Butylene glycol, glycols such as hexamethylene glycol and diethylene glycol, trifunctional polyols such as glycerin, trimethylolpropane and triethanolamine, tetrafunctional polyols such as diglycerin and pentaerythritol, 6 functional polyols such as sorbitol, and 8 functionalities such as sugar. Polyols, addition polymers of alkylene oxides and aliphatics, alicyclics, aromatic amines corresponding to these polyols and addition polymers of the alkylene oxides and polyamide polyamines, for example,
Examples thereof include phthalic acid dihydrazide, ethylenediamine, adipic acid dihydrazide, hydrogenated methylenediphenyldiamine, or a polypropylene oxide adduct with aniline.

Of these, glyceride ricinoleate, polyester polyol of ricinoleic acid and 1,1,1-trimethylolpropane, and the like are preferable.

Examples of the polyether polyol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 4,4'-dihydroxyphenylpropane, 4,4'-dihydroxy. Dihydric alcohols such as phenylmethane and glycerin, 1,1,1-
Trimethylolpropane, 1,2,5-hexanetriol, pentaerythritol and other trihydric or higher polyhydric alcohols and addition polymers of ethylene oxide, propylene oxide, butylene oxide, and alkylene oxides such as α-olefin oxide. To be

As other polyols, the main chain is carbon-
Carbon polyols such as acrylic polyols, polybutadiene polyols, polyisoprene polyols, hydrogenated polybutadiene polyols, polyols obtained by graft polymerizing AN (acrylonitrile) or SM (styrene monomer) with the above-mentioned polyols, polycarbonate polyols, PTMG (polytetramethylene). Glycol), dimer acid / polyol polyester polyol, and the like.

As the polyisocyanate used in the present invention, aromatic polyisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate and the like can be used. Examples of aromatic polyisocyanates include diphenylmethane diisocyanate (4,4-MDI,
2,4-MDI / 4,4-MDI mixture, etc.), polymethylene polyphenylene polyisocyanate (crude MDI),
Tolylene diisocyanate (TDI), polytolylene polyisocyanate (crude TDI), xylene diisocyanate (XDI), naphthalene diisocyanate (ND)
I) and the like. Hexamethylene diisocyanate (HDI) etc. are mentioned as an aliphatic polyisocyanate. Examples of the alicyclic polyisocyanate include isophorone diisocyanate (IPDI) and the like. In addition to the above, polyisocyanate obtained by modifying the above polyisocyanate with carbodiimide (carbodiimide modified polyisocyanate), isocyanurate modified polyisocyanate, urethane prepolymer (for example, a reaction product of polyol and excess polyisocyanate and having an isocyanate group as a molecule) It can also be used. These are used alone or as a mixture. Among these, diphenylmethane diisocyanate, polymethylene polyphenylene polyisocyanate, and carbodiimide-modified polyisocyanate are preferable.

The insulating polyurethane resin in the present invention means a cured product having a volume resistivity value (Ω · cm) of 10 ¹⁰ Ω · cm or more measured at 25 ± 5 ° C. and 65 ± 5% RH. What can be done. Furthermore, the dielectric constant is 6 or less (1
MHz), and the dielectric breakdown voltage is preferably 15 KV / mm or more. The insulating polyurethane resin has a volume resistivity value of 10 ¹⁰ Ω · cm or more, preferably 10 ¹⁰ Ω · cm or more, which is obtained by adjusting the oxygen content of the polyol, the concentration of eluted ions or the number of types of eluted ions. Is 10 ¹¹ Ω
・ It can be obtained by adjusting to cm or more. In particular, when the volume resistivity is 10 ¹¹ Ω · cm or more, the insulating property of the cured product is maintained, and for example, a transformer, an electric wire, a coil, a ceramic printed circuit board, an epoxy / acrylate printed circuit board, an optical cable joint, an electric wire cable joint,
It can be suitably used as an insulating material used for capacitors, paper phenol printed boards, polyimide printed boards, etc., and a sealant for electronic parts. To measure the volume resistivity,
It is performed according to JIS C 2105. Specifically, using SE-10E manufactured by Toa Denpa Kogyo KK, 25 ± 5 ° C., 65 ±
A measurement voltage of 500 V is applied to the sample (thickness: 3 mm) at 5% RH, and the value after 60 seconds is measured.

The one-pack type insulating polyurethane resin composition of the present invention has an excess of the polyisocyanate in the polyol, preferably an NCO / OH equivalent ratio of 1.4 to.
A urethane prepolymer obtained by reacting at 2.5, in which the terminal isocyanate group is blocked with a blocking agent, is contained. The urethane prepolymer can be manufactured by an ordinary manufacturing method.

The content of terminal isocyanate groups in the urethane prepolymer is preferably 1 to 10% by weight,
More preferably, it is 1 to 5% by weight. When the terminal isocyanate group content is 1 to 10% by weight, the insulating cured product tends to be flexible and have a low glass transition temperature.

Examples of the blocking agent include oxime compounds such as methyl ethyl ketoxime and methyl isobutyl ketoxime, lactams such as ε-caprolactam, and the like.
Active methylene compounds, phenols, imidazoles,
Dicyclohexylamine, dimethylamine, diethylamine, ethylbutylamine, dibutylamine, diphenylamine, dipropylamine, diisopropylamine,
Dioctylamine, ethylphenylamine, ethylcyclohexylamine and the like can be mentioned. These are used alone or as a mixture. Among these, oxime compounds and lactams are preferable, and methyl ethyl ketoxime is particularly preferable.

The addition amount of the blocking agent is usually preferably 1 equivalent or more and less than 2 equivalents, more preferably 1.05 equivalent to the terminal isocyanate group of the urethane prepolymer.
~ 1.5 equivalents. The reaction between the urethane prepolymer and the blocking agent is performed at 25 to 100 ° C. until the NCO group disappears. As the reaction solvent, solvent naphtha, paraffin compounds, methyl ethyl ketone, toluene, ethyl benzene and mixtures thereof can be used. If the composition obtained has a high viscosity, it may be diluted with a diluent.

As the solvent for the one-pack type insulating polyurethane resin composition of the present invention, for example, polyol, monool, hydrocarbon, etc. can be used, and as the plasticizer, diisononyl phthalate (DINP), diundecyl phthalate, etc. (DUP), Triisodecyl trimellitate (TIT
M), trioctyl trimellitate (TOTM), soybean oil epoxy compound and the like may be added.

When a cured product of an insulating polyurethane resin is obtained from the one-pack type insulating polyurethane resin composition of the present invention,
It is preferable to use a curing agent so that the obtained cured product has a desired hardness. The curing agent may be added to the one-component type insulating polyurethane resin composition during curing, or may be added in advance to the one-component type insulating polyurethane resin composition.

As the curing agent, for example, ricinoleic acid glyceride, adipic acid dihydrazide (ADH), polyol compounds such as polybutadiene polyol, polyisoprene polyol, aromatic and alicyclic polyol, polyethylene polyamine, metaxylene diamine (MXDA),
Xylene diamine (XDA), isophorone dian (IP
DA), hexamethylenediamine (HDA), ethylenediamine (EDA), diethylenetriamine (DET)
A), triethylenetetraamine (TETA), tetraethylenepentamine (TEPA), polyamide polyamine, ketimine, diethanolamine, and other amine compounds, and 1 to 3 times equivalent of EDA with ethylene oxide or propylene oxide adduct, aliphatic , Alicyclic,
Addition products of alkylene oxides with aromatic amines and ethylene oxide, propylene oxide, phthalic acid dihydrazide, maleic acid dihydrazide, carbon dihydrazide, sebacic acid dihydrazide, dodecane nitric acid dihydrazide, isophthalic acid dihydrazide, phthalic acid diethylenediamine, adipic acid diethylenediamine Polyamide polyamines such as dimethaxylenediamine phthalate and dimetaxylenediamine adipate. These curing agents may be used as a mixture.

The curing agent is preferably mixed in an amount of 0.5 to 2 equivalents based on the blocked isocyanate group of the urethane prepolymer. Further, if necessary, in order to promote the dissociation of the blocked isocyanate group and the reaction between the free isocyanate group and the hydroxyl group of the polyol, an organometallic (Sn, Zn) compound, a tertiary amine compound or the like is used as an activation catalyst. The above-mentioned amine compound (can be used in combination).

The one-component insulating polyurethane resin composition of the present invention further comprises, if necessary, a flame retardant, a filler, a colorant, a plastic powder, an aliphatic, an alicyclic, an aromatic hydrocarbon, an insect repellent. , An antifungal agent, an antibacterial agent, an ultraviolet absorber, an antioxidant, starches, and celluloses may be added.

From the one-pack type insulating polyurethane resin composition of the present invention, preferably 10 to 60 at 120 to 170 ° C.
An insulating cured material is obtained by heating for a minute.

The one-component insulating polyurethane resin composition of the present invention is used in an electric washing machine, a toilet seat, a water heater, a water purifier, a bath,
Electronic used in switch parts and electric tools of dishwashers, etc., sealant for sealing electric / electronic circuits contained in electric parts from moisture and humidity, electricity,
It is preferably used as a sealing agent or coating agent for electronic devices, and as an insulating material for capacitors, converters, transformers, electric wires, coils, and electrical components (electronic components of automobiles).

[0029]

EXAMPLES The present invention will be described in more detail based on the following examples. However, the present invention is not limited to these examples. First, the test methods used in Examples and Comparative Examples will be described below.

Measurement of volume resistivity (Ω · cm) Using SE-10E manufactured by Toa Denpa Kogyo KK, 25 ± 5 ° C., 6
A measurement voltage of 500 V is applied to the sample (50 mm × 50 mm, thickness: 3 mm) at 5 ± 5% RH, and the numerical value after 60 seconds is measured.

Hardness measurement Two samples (50 mm × 50 mm, thickness: 3 mm) were stacked (thickness: 6 mm), and the hardness was measured according to JIS K 6253.
Measure according to. As a hardness tester, Asker A type manufactured by Kobunshi Keiki Co., Ltd. is used.

Example 1 The polyols and tolylene diisocyanates (T
DI-100, 2,4-TDI 100% by weight)
The reaction was carried out at a ratio of H: NCO = 1: 1.6 and the terminal isocyanate group of the obtained urethane prepolymer was methylethylketoxime (MEKO) (R (alkyl group)-
H: NCO = 1.05: 1 (equivalent ratio)) to obtain a one-component insulating polyurethane resin composition containing a blocked isocyanate group-containing urethane prepolymer. Using the obtained composition as a curing agent, adipic acid dihydrazide (ADH) and ricinoleic acid glyceride (0.5
/0.5 equivalent) to block NCO against block N
CO / R-H = 1/1 equivalent, 120-170 ° C,
It was cured in 10 to 30 minutes to obtain a sample.

The samples thus obtained were subjected to the heat treatment and moisture heat treatment described below, and the volume resistivity, hardness and weight before and after these treatments were measured. The results are shown in Table 2. The hardness and weight are shown as the rate of decrease relative to the value (initial value) before treatment. Further, in Table 2, VR indicates the volume resistivity value, WT indicates the weight reduction rate with respect to the initial value, and HA indicates the hardness reduction rate with respect to the initial value. The physical properties of the polyol used are shown in Table 3.

Heat resistance treatment The sample is left at 150 ° C. for 4 hours in a DN-62 thermostat manufactured by Yamato Scientific Co., Ltd.

Moisture-resistant heat treatment Co., Ltd. Hirayama Seisakusho Pressure Cooker PC-2
Samples in 42HS-A at 121 ° C, 100% RH,
Leave for 24 hours under the condition of 2 atm.

Examples 2 to 8 and Comparative Examples 1 to 3 Using the polyols shown in Table 1, a one-pack type insulating polyurethane resin composition containing a blocked isocyanate group-containing urethane prepolymer was obtained according to Example 1. A sample was obtained from the obtained composition according to Example 1. The volume resistivity, hardness and weight of the obtained sample were measured before and after heat treatment and moisture resistance heat treatment. The results are shown in Table 2.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

As is clear from Table 2, the oxygen content is 2
A cured product of an insulating polyurethane resin obtained by reacting a polyol having a weight ratio of 2% by weight or less and an iodine value of 155 mgKOH / g or less with polyisocyanate is 121 ° C., 1
Even after standing for 24 hours under the condition of 00% RH and 2 atm,
Even after being left for 24 hours in a constant temperature bath of 50 ° C., the rate of decrease in hardness and weight could be suppressed to 10% or less, and there was almost no deterioration in insulation.

[0041]

INDUSTRIAL APPLICABILITY The one-pack type insulating polyurethane resin of the present invention can give an insulating cured product whose hardness hardly changes even when exposed to high temperature or high temperature and high humidity, and whose insulating property does not decrease. Moreover, it is easy to handle.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J034 BA01 CA03 CA04 CA05 DC50                       DF01 DF02 DG03 DG04 DG05                       DG06 DL01 DQ08 GA05 GA06                       HA01 HA07 HC12 HC13 HC61                       HC64 HC67 HC71 HD02 HD03                       HD04 HD07 HD12 QB06 QB19                       RA14                 5G305 AA11 AB26 BA09 BA26 CA18                       CA55 CA56

Claims (2)

[Claims] 1. A urethane prepolymer obtained by reacting a polyol having an oxygen content of 22% by weight or less and an iodine value of 155 mgKOH / g or less with a polyisocyanate, wherein a terminal isocyanate group of the urethane prepolymer is blocked. A composition for a one-component insulating polyurethane resin, characterized by comprising: 2. The composition for one-component insulating polyurethane resin according to claim 1, which is for insulating electrical or electronic parts.