JPH05112625A - Urethane resin composition for casting and production of moisture-proof insulated control substrate for electric washing machine - Google Patents

Abstract

PURPOSE:To obtain the subject composition containing a liquid polybutadienepolyol, etc., having excellent flame resistance, flexibility, resistance to wet heat and reliability and useful for a control substrate for electric washing machine. CONSTITUTION:The objective composition containing (A) 100 pts.wt. liquid polybutadienepolyol (preferably having 1000-3000 number-average molecular weight), (B) a bifunctional castor oil transesterified product, preferably of 60-90 pts.wt., (C) a phosphoric acid ester such as triphenyl phosphate, preferably of 80-100 pts.wt., (D) hydrated alumina, preferably of 400-500 pts.wt., (E) monofunctional castor oil transesterified product, preferably of 10-20 pts.wt. and (F) a polyisocyanate such as tolylene diisocyanate (the blend ratio is preferably 0.8-1.3 equivalent based on total amount of hydroxyl group of these components A to C). Furthermore, the composition is cast onto a control substrate for electric washing machine and cured to provide the objective moisture-proof insulated control substrate for electric washing machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a urethane resin composition for casting, which is suitable for a moisture-proof insulation treatment, and a method for producing a control board for a washing machine treated with the urethane resin composition.

[0002]

2. Description of the Related Art Electric equipment tends to be smaller and lighter and has more and more functions year by year, and control boards mounted on various electric equipment for controlling the electric equipment are subjected to an insulation treatment for the purpose of protecting it from moisture and dust. There is. As the insulation treatment method, a protective coating treatment with a paint such as an acrylic resin or a silicone resin or a casting treatment with a urethane resin is widely adopted. As described above, the control board is used in a harsh environment, particularly in high humidity, and is mounted and used in equipment such as a washing machine and an automobile.

However, there is a problem that the paint cannot completely protect the pin legs of the electronic parts mounted on the control board, resulting in poor water resistance. On the other hand, the urethane resin used for casting has excellent insulation and water resistance, but since the control board is cast, the influence of stress on various electronic components and base materials mounted There is a demand for a urethane resin composition for casting, which has flexibility to suppress the above and flame retardancy to improve the safety. Conventionally, in order to improve the flame retardancy of the urethane resin composition, a method of blending an inorganic filler with the urethane resin has been performed, but with this method, the viscosity of the urethane resin composition increases, which causes a problem in workability. Occurs, and the cured product becomes hard and flexibility decreases, so that there is a problem that crack resistance is inferior.

Further, in order to reduce the viscosity of the urethane resin composition containing an inorganic filler and improve the flexibility of the cured product, a certain amount of a diluent having a low viscosity and having no hydroxyl group may be added. However, there is a problem in this method that if the blending amount is too large, the insulating property and the moist heat resistance of the resin cured product decrease.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and is excellent in flexibility, flame retardancy and resistance to moist heat, and a casting urethane resin composition and these urethane resin compositions. (EN) Provided is a method for manufacturing a control board for a washing machine, which performs a moisture-proof insulation treatment with a product.

[0006]

The present invention comprises (a) liquid polybutadiene polyol, (b) difunctional castor oil transesterification product, (c) phosphate ester, (d) hydrated alumina, and (e) monofunctional. Castor oil transesterification product and (f)
The present invention relates to a casting urethane resin composition containing a polyisocyanate and a method for producing a moisture-proof insulated washing machine control substrate in which the casting urethane resin composition is cast and cured on a washing machine control substrate.

The liquid polybutadiene polyol (a) used in the present invention preferably has a number average molecular weight of 700.
1.4 polybutadiene polyols, which are ˜8000, more preferably 1000 to 3000, are preferably used. As this commercial product, for example, the product name Poly b
d R-45HT, R-45M (made by Idemitsu Petrochemical Co., Ltd.), etc. are mentioned.

The (b) bifunctional castor oil transesterification product used in the present invention is a transesterification reaction product of castor oil and natural fats and oils having substantially no hydroxyl group, and as a commercial product, for example, trade name URIC Y- 403 (made by Ito Oil Co., Ltd.) and the like. The mixing ratio of the bifunctional castor oil transesterification product (b) is 50 to 100 with respect to 100 parts by weight of the (a) from the viewpoint of casting workability and flexibility of the cured product.
The range of parts by weight is preferable, and the range of 60 to 90 parts by weight is more preferable.

Examples of the (c) phosphoric acid ester used in the present invention include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate and the like. The blending ratio of the component (c) is 100 from the component (a) from the viewpoint of casting workability, flexibility of the cured product and resistance to moist heat.
The amount is preferably 50 to 150 parts by weight, more preferably 80 to 100 parts by weight with respect to parts by weight.

Commercially available products of (d) hydrated alumina used in the present invention include, for example, trade names, C-303H and C-30.
8H, C-315H (manufactured by Sumitomo Chemical Co., Ltd.) and the like. The mixing ratio of the component (d) is from the above-mentioned component (a) 1 from the viewpoint of casting workability, flexibility of the cured product, resistance to moist heat and flame retardancy.
Preferably 360 to 650 parts by weight with respect to 00 parts by weight,
It is more preferably 400 to 500 parts by weight.

The (e) monofunctional castor oil transesterification product used in the present invention is a transesterification product of castor oil and a natural fat or oil having substantially no hydroxyl group, and the bifunctional castor oil transesterification product is further esterified. As a commercially available product, for example, product name URIC-H-31 (manufactured by Ito Oil Co., Ltd.)
And so on. From the workability of casting, the flexibility of the cured product and the resistance to moist heat, the blending ratio of the component (e) is the same as that of the component (a).
It is preferably 5 to 40 parts by weight, more preferably 10 to 20 parts by weight, relative to 100 parts by weight of the component.

The polyisocyanate (f) used in the present invention is used as a curing agent for the above components (a), (b) and (c). For example, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene. Diisocyanate, xylylene diisocyanate, diphenyl sulfone diisocyanate, triphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanate methyl-3,5,5
-Trimethylcyclohexyl isocyanate, 3-isocyanate ethyl-3,5,5-trimethylcyclohexyl isocyanate, 3-isocyanate ethyl-3,
5,5-triethylcyclohexyl isocyanate, diphenylpropane diisocyanate, phenylene diisocyanate, cyclohexylylene diisocyanate,
Polyisocyanates such as 3,3′-diisocyanate dipropyl ether, triphenylmethane triisocyanate and diphenyl ether-4,4′-diisocyanate, or the above-mentioned isocyanates with phenols, oximes, imides, mercaptans, alcohols, ε
-Caprolactam, ethyleneimine, α-pyrrolidone,
Examples thereof include those blocked with diethyl malonate, hydrogen sulfite, sodium, boric acid and the like. The blending ratio of the (f) polyisocyanate is such that the isocyanate groups in the polyisocyanate are based on the total amount of the hydroxyl groups of the components (a), (b) and (c) from the curability and characteristics of the urethane resin composition. It is preferably used so as to be 0.8 to 1.3 equivalents. The component (d) and the component (f) are
You may use 2 or more types together.

Further, the urethane resin composition of the present invention may be mixed with various additives such as known dehydrating agents, curing accelerators, pigments and dyes, if necessary.

A moisture-proof insulated washing machine control board is manufactured using the casting urethane resin composition according to the present invention. As a manufacturing method thereof, a generally known discharge casting method or the like is used. The composition may be cast on a control substrate and cured. Curing after casting is performed at room temperature or by heating.

[0015]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited thereto. "Part"
"Parts" means "parts by weight". Examples 1 to 3 and Comparative Examples 1 to 2 Liquid properties and cured physical properties of the urethane resin compositions obtained with the blending composition and blending amount (parts by weight) shown in Table 1 were measured by the methods described below. Further, the reliability was evaluated at the same time by using a washing machine control board equipped with a memory IC, a resistor, a condenser and the like. The results are shown in Table 1. (1) Viscosity: Measured using a B type rotational viscometer. (2) Hardness: 20 g of the composition is poured into a metal petri dish having a diameter of 60 mm and cured, and then the cured product is taken out from the metal petri dish. After completion of each deterioration test, the measurement was performed by allowing the sample to stand up to a measurement temperature of 25 ° C. and measuring with a Shore A hardness meter. (3) Flame retardancy: Test piece thickness 2 m according to UL-94 method
It was measured in m. (4) Volume resistivity: Measured according to JIS C-2105. (5) Coverability of pin feet: The control substrate was treated with the compositions of Examples and Comparative Examples, and the coated state was observed with the naked eye. (6) Water resistance: The soldering surface on the back surface of the control board for a washing machine was immersed in water, and a voltage of 100 V was applied at 25 ° C. for 75 hours to visually observe the corrosion state of the pin legs of each electronic component.

[0016]

[Table 1]

From the results shown in Table 1, the compositions of Examples 1 to 3 have UL-94V-0 flame retardancy, and the flame retardance does not decrease even if they are deteriorated by heating at 80 ° C. Hardness of cured product is 80
No significant change in hardness is observed even when deteriorated by heating at ℃. The pressure cooker test also shows that the composition of the comparative example has less change in hardness and is less likely to be hydrolyzed.

[0018]

The casting urethane resin composition of the present invention comprises:
It is possible to obtain a cured product having high flame retardancy and excellent heat and moisture resistance. By using this urethane resin composition for moistureproof insulation, a highly reliable control board for a washing machine can be obtained. ..

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area B29L 31:34 4F

Claims (2)

[Claims] 1. (a) Liquid polybutadiene polyol,
(B) Bifunctional castor oil transesterification product, (c) phosphate ester, (d) hydrated alumina, (e) monofunctional castor oil transesterification product, and (f) casting urethane containing Resin composition. 2. A method for producing a moisture-proof insulated washing machine control board, comprising casting and curing the casting urethane resin composition according to claim 1 on a washing machine control board.