JPS62100513A - Curable composition - Google Patents

Abstract

PURPOSE:To obtain a composition of low viscosity and good workability, capable of giving coating film flexible at any temperatures, useful for protective film for printed-wiring board, by blending a polyol, polyisocyanate and, as a plasticizer, highly-acrylated castor oil. CONSTITUTION:(A) A polyol [pref. high-viscosity hydrocarbon-based are (e.g., polybutadiene polyol), especially with a OH value <=70mgKOH/g, castor oil or its derivative (e.g., partially acylated castor oil)] and (B) a polyisocyanate (e.g., tolylene diisocyanate) are blended in a preferable ratio of the NCO group of the component B to the OH group of the component A 0.8-1.4. The resulting blend is incorporated with (C) as a plasticizer, highly-acylated castor oil (pref. with a OH value <20mgKOH/g) in such an amount as to be pref. 2-50wt% based on the total amount of the components A and B, thus obtaining the objective two-pack nonsolvent polyurethane-based curable composition.

Description

Detailed Description of the Invention In industrial application field 2, the invention is directed to a two-component solvent-free polyurethane-based curable M
In particular, polyol component (A) used to protect printed wiring boards, B1) Isocyanate component (
The present invention relates to a two-component solvent-free polyurethane curable composition comprising B) and a plasticizer component (C).

Conventional technologyProtective coatings for printed wiring boards were first used in the United States for military purposes, but in recent years the scope of use of printed wiring boards has rapidly expanded and the conditions under which they are used have become more diverse. In addition, as requirements for maintaining the performance of printed wiring boards have become more stringent, protective coatings have also been applied to printed wiring boards used in automatic vending machines, electric washing machines, automotive electrical equipment, and rx machine tools. It is becoming common to do this.

Resins used for protective coatings for printed wiring boards include:
There are solvent-based acrylic resins, solvent-based urethane resins, two-part urethane resins, solvent-based epoxy resins, and silicone resins, but two-part solvent-free urethane systems are advantageous when considering price, working environment, and performance. It can be said that.

Conventionally, a method using polybutadiene polyol as a polyol component has been proposed as a urethane system for this purpose. When polybutadiene polyol is reacted with polyisocyanate, it exhibits flexibility even at low temperatures and has excellent electrical properties.

A method using castor oil as a polyol component has also been proposed. By reacting castor oil with polyisocyanates, protective coatings with excellent electrical properties are obtained.

Furthermore, attempts have also been made to use the above-mentioned polybutadiene polyol and castor oil in combination as polyol components.

Problems to be Solved by the Invention However, since polybutadiene polyol has an extremely high viscosity, it has a serious drawback of extremely poor workability when handling it, and the use of this resin alone has limited its widespread use. be. Therefore, in order to overcome this drawback, considerable amounts of solvents are added to polybutadiene polyols, and mineral oils and plasticizers (such as dioctyl phthalate) are added to polybutadiene polyols, but the use of solvents worsens the working environment. , is unsuitable as it poses a fire hazard, and the use of mineral oil and ordinary plasticizers will lower the physical properties of the cured product.I-1 If the cured product is placed under high temperature conditions, the mineral oil and plasticizer will volatilize. However, as the cured product decreases and shrinks, its hardness increases, causing the problem of damaging the wiring.

Furthermore, when castor oil is used, the hardness of the cured product is too high and it lacks stretchability, especially at low temperatures, so that L2 is still unsatisfactory as a printed wiring board protective coating.

Furthermore, even in systems using polybutadiene polyol and castor oil in combination, the above-mentioned drawbacks of each component cannot be overcome.

After all, in addition to the generally required properties such as electrical properties and mechanical strength, a protective coating for a printed wiring board must have (1) low viscosity and easy handling, and (2) does not cause weight loss or increase in hardness at high temperatures. It is required to maintain flexibility even in low-temperature environments, but until now it has not been possible to find a urethane system that satisfies all of these properties.

In view of the above-mentioned circumstances, the present invention has been developed to provide a cured product that has low viscosity before curing, electrical insulation and elasticity after curing, and does not cause weight loss or increase in hardness even under high temperature conditions. Moreover, the purpose is to provide a urethane system that maintains flexibility even in low-temperature environments.

Means for Solving the Problems The present invention comprises [polyol component (A), polyisocyanate I component (
A two-component solvent-free polyurethane system 1 comprising B) and a plasticizer component (C), wherein the plasticizer component (C) comprises highly acylated castor oil. curable composition. '', and by discovering the use of a specific plasticizer component, the above objective has been achieved.

A detailed explanation of the invention will be given below.

As the polyol component (A) in the present invention, a wide range of polyols can be used as long as they are ordinary polyols for producing polyurethane, but from the viewpoint of electrical properties and mechanical strength, high viscosity hydrocarbon polyols, castor oil, It is also particularly desirable to use a tenon inviting body.

Here, the high viscosity hydrocarbon polyol is a hydrocarbon polyol with a large hydroxyl equivalent.

In particular, hydrocarbon polyols with a hydroxyl value of 70 mg KO) (/g or less) are used, and specific examples include polybutadiene polyol, its hydrogenated product, and polyolefin polyol. (above) may be a Kyodo union with -. Commercially available products include, for example, rPB R-45HT J manufactured by Idemitsu Petrochemical Co., Ltd., which is a polybutadiene polyol, rG-1000J manufactured by Memoto Soda Co., Ltd., and " Examples include Polytail HAJ.

Castor oil, as is well known, is a triglyceride whose main component is ricinoleic acid.

Examples of castor oil derivatives include partially acylated castor oil, partially dehydrated castor oil, and castor oil-hydroxyl group-free natural oil and fat transesterification products.

Among these, partially acylated castor oil refers to castor oil partially acylated to the extent that the hydroxyl value does not fall below 20 mgKOH/g. Among acylations, acetylation is important.

Partially dehydrated castor oil is made by extracting castor oil from sulfuric acid, phosphoric acid, p-1
Partially dehydrated by heating in the presence of an acidic catalyst such as luenesulfonic acid until the hydroxyl value does not fall below 20 mg KCDI/g.

The castor oil-hydroxyl group-free natural oil and fat transesterification reaction product is obtained by transesterifying castor oil and hydroxyl group-free natural oil and fat at an appropriate ratio, such as a weight:ratio of 90 to 30:10 to 70. Things:? -Uh. During the esterification reaction, 1. Small amounts of low molecular weight polyols may also be present. Examples of natural fats and oils that do not contain hydroxyl groups include linseed oil, tung oil, →-seed oil, soybean oil, coconut oil, balm oil, palm kernel oil, arachis oil, sunflower oil, safflower oil, lard, and other vegetable oils. Or animal oil is used.

Next, as the polyisocyanate component (B), tolylene diisocyanate, diphenylmethane diisocyanate or carbodiimide-modified diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, diphenylsulfone diisocyanate,
Triphenylmethane diisocyanate, hexamethylene diisocyanate, 3-incyanate ethyl 3゜5
．． 5-4 Limethylcyclohexyl isocyanate, 3-
Incyanate ethyl-3,5,5-trimethylcyclohexyl isocyanate, 3-incyanate ethyl-
3,5,5-trimethylcyclohexyl isocyanate, diphenylpropane diisocyanate, phenylene diisocyanate, cyclohexylylene diisocyanate, 3゜3-diisocyanate dipropyl ether, triphenylmethane triisocyanate, diphenyl ether-4,4-diisocyanate, isofo-C diisocyanate, etc. can give. Prepolymers having terminal incyanate groups derived from these polyisocyanates and various polyols can also be used. Incidentally, inactive process oil, fatty acid ester, etc. may be added to the polyincyanate component (B) in order to adjust the viscosity and improve storage stability.

As the plasticizer component (C) which is a characteristic component of the present invention, highly acylated castor oil is used. Here, highly acylated castor oil refers to castor oil that has been completely or nearly completely acylated, and has a hydroxyl value of 20 mgKOH/
Refers to less than g.

Acylation of castor oil is carried out by ordinary acylation means, and among the acylations, acetylation is the most important, and industrially it is mainly limited to this acetylation, but in some cases partial propionylation etc. Sometimes I do. As the acetylation method, a method of reacting with ketene and a method of reacting with glacial acetic acid are also employed, but acetylation with butyric anhydride is industrially most advantageous. Acylation is performed when the hydroxyl value is less than 20 mgKOH/g or Om
Proceed until gKOH/3.

The blending ratio of the above-mentioned polyol component (A), polyisocyanate component (B) and plasticizer component (C) is selected from the following range.

First, the blending ratio of the polyol component (A) and the polyinsocyanate component (B) is as follows:
It is preferable that the amount of incyanate groups in the polyol component (A) be 0.8 to 1.4 equivalents tt- to the total amount of hydroxyl groups in the polyol component (A), since sufficient curing can be achieved.

Next, 1) The highly aba/lylated castor oil which is the plasticizer component (C) is combined with the polyol component (A) and the polyisocyanate component (
1 to 60 parts by weight 6, preferably 2 parts per total amount of B)
It is desirable to use up to 50% by weight. If the amount is too small, the desired layering effect cannot be obtained, while if the amount i is too large, the cured product will lack mechanical strength.

Highly acylated castor oil, which is the plasticizer component (C), reduces the viscosity of the polyol component (A), so it is usually blended into the polyol component (A). ), it may be blended with both the polyol component (A) and the polyisocyanate component (B), or it may be blended simultaneously when both components (A) and (B) are mixed. good. Furthermore, when the polyisocyanate component (B) is a prepolymer, the plasticizer component (C) may be added as a diluent during the production of the prepolymer.

By blending agent component (C), the viscosity of the thread is reduced, making it easier to perform tasks ranging from mixing to coating on wiring boards, etc. j interval is also shortened.

In addition, ten silk acids (:, fillers, pigments, flame retardants, other plasticizers, curing accelerators, crosslinking agents, reinforcing materials,
Various additives such as antioxidant LIx agents, ultraviolet absorbers, moisture absorbers, etc. can be blended. However, substantially no solvent is used.

The uninvented composition is a two-component solvent-free solution for protecting printed wiring boards in vending machines, air washers, hot water toilet seats, near conditioners, automatic accessories, machine tools, etc. It is particularly useful when combined with tanning acids, and can be used by methods such as coating, casting, dipping, botting, and botting. In addition, we also provide sealing for electronic components such as capacitors, coils, and HICs (coating for L, casting, positing,
It can also be used for dipping, encabbing/eating, sealing, etc. purposes.

Function The highly acylated castor oil constituting the plasticizer component (C) in the present invention has a high viscosity of the polyol component (A) or the viscosity of the system after mixing the polyol component (A) and the polyisocyanate component (B). plays a role in significantly reducing

Then, since sufficient [iJ plastic effect is produced, I′I3I
! It maintains the flexibility of the compound and effectively suppresses the increase in hardness of the cured product even under low temperature conditions.

In addition, it has low water absorption and excellent electrical insulation properties, so it does not deteriorate the electrical properties of the cured product.

Furthermore, since highly acylated castor oil has a molecular weight of 900 or more and low volatility, even if the cured product is kept under high temperature conditions for a long period of time, there is little loss due to volatilization and there is no risk of hardness decreasing.

EXAMPLES Next, the curable composition of the present invention will be further explained with reference to Examples.

Pass 71 multi-second A4 go benear? Koyu! Synthesis Example 1 Castor oil (hydroxyl value: 160 ll1gKDH/g
, viscosity near 00 cps/25°C) and 915 g of acetic anhydride in a flask equipped with a thermometer, a stirrer, and a reflux condenser.
The reaction was continued for about 2.5 hours by heating to 150°C.

Then, the reflux condenser was replaced with a distillation condenser, and the temperature was gradually increased to recover by-produced acetic acid and unreacted acetic anhydride as an external distillate.

During this time, the degree of depressurization was gradually increased using the aspirator. The temperature of the system reached 200°C after 1 hour, so it was kept at this temperature for 15 minutes and then cooled.

As a result, highly acetylated castor oil having a wood M base value: Q mgKOH/g and a viscosity of 230 cps/25°C was obtained.

Synthesis Example 2 120 g of castor oil and 750 g of acetic anhydride
The reaction was continued for about 25 hours by heating to ~150°C, and the same procedure as in Synthesis Example 1 was carried out to obtain highly acetylated castor oil.

Water Sj, L value is 18mgkOH/g, viscosity is 240
eps/25°C.

Preparation of polyurethane group '1 Polyol component (A), polyisocyanate component (B)
The following were prepared as the plasticizer component (C).

Polyol component (A) (A1) Polybutadiene polyol (PI3 R-45HT manufactured by Idemitsu Petrochemical Co., Ltd., several thousand equivalents - f amount 28 (
10, number of functional groups: 2.2-2.4, iodine value = 398,
Hydroxyl value: 4cmgKOH/g, viscosity: e800c
ps/25℃) (A2) Castor oil (Hydroxyl value: IHm
gKOH/g, viscosity: 700 cps/25°C) (A3) Partially acetylated castor oil (produced according to Synthesis Example 1 above, hydroxyl value: 140 mgKOH/g, viscosity: 550 cps/25°C) (A4) Partially dehydrated castor oil (produced by heating and reacting castor oil at 190 to 250°C under reduced pressure in the presence of acidic sodium sulfate, hydroxyl value: 137 mgKDH/g, viscosity =
490 cps/25°C) (A5) Castor oil - hydroxyl group-free natural fat and oil transesterification reaction product (100 g of castor extract and 100 g of rapeseed yuzu) in the presence of sodium sodium carbonate methylate at 180 to 230°C in a stream of nitrogen gas to approx. Manufactured by reacting for 2 hours, hydroxyl value = 84 KOH/g, viscosity 172 cps/25
℃) Polyisocyanate-1・Component (B) (B1) Carbodiimide-modified 4.4゛-diphenylmethane diisocyanate (Memoto Boliu L/Tan Co., Ltd. Millionate MTL) (B2) Carbodiimide-modified 4.4 of J bipod (B1)
Prepolymer of '-diphenylmethane diincyanate and castor oil (B3) l-diisocyanate-1-tobo) butadiene boriol (manufactured by Idemitsu Petrochemical Co., Ltd. HTP
-9) Highly acylated castor oil (C) (C1) Highly acetylated castor oil (obtained in the above Synthesis Example 1, hydroxyl value: Om3KOH/g, viscosity IW: 23
0 cps/25°C) (C2) Highly acetylated castor oil (obtained in Synthesis Example 2, hydroxyl value: 18 mgKOH/g, viscosity: 2
40eps/25°C) Examples 1 to 6 Of the above components, first combine component (A) and component (C) and check the viscosity, then mix this with component (B) and check the viscosity. At the same time, the hardness (at room temperature and low temperature), tensile strength, volume resistivity, It was used to measure water absorption. Among the measurement items, hardness and tensile strength were measured based on JIS K [3301], and volume resistivity and water absorption were measured based on JIS KS911.

In addition, the cured product -1- was kept at a temperature of 100°C for 120 hours, and the weight loss on heating was measured.

Table 1 shows the types and blending ratios of each component, and the results.

Note that Comparative Examples that do not use component (C) are also shown in Table 1.

As is clear from Table 1, in the composition of the present invention using highly acylated castor oil as the plasticizer component (C), the viscosity of the system is low, the cured product has high elongation, and It can be seen that flexibility is maintained under both low-temperature conditions, and there is no increase in hardness due to volatilization and dissipation even under high-temperature conditions.

On the other hand, it can be seen that in Comparative Example 1, in which polypolybutadiene polyol was used as the polyol component (A) and no plasticizer component (C) was blended, the viscosity was extremely high.

In addition, in Comparative Example 2 in which castor oil was used as the polyol component (A) and no plasticizer component (C) was blended, the hardness of the cured product, especially at low temperatures, was high, making it suitable as a protective coating for printed wiring boards, etc. Not yet.

Furthermore, in Comparative Example 3, in which polybutadiene polyol and castor oil were used together as the polyol component (A) and no plasticizer component (C) was blended, the viscosity was high.
High hardness at low temperatures.

On the other hand, in Comparative Example 4, in which process oil was blended into the polyol component (A) and dibutyl phthalate was blended into the polyisocyanate component (B), the hardness at low temperatures was high, and the weight loss under high temperature conditions was ignored. I can't do it.

Similarly, polyol component (A) and polyisocif; *
In Comparative Example 5, in which process oil was blended into both component (B), the weight loss was remarkable under high temperature conditions.

As mentioned above, all of the comparative examples are inferior in viscosity, hardness at low temperatures, and change at high temperatures, and are therefore unsatisfactory as protective coatings for printed wiring boards and the like.

Effects of the Invention Since the Mi oxide of the present invention has a low viscosity, it is easy to work and the working time can be significantly shortened.

In addition, the obtained cured product has good flexibility, and even if it is kept under low temperature conditions, the hardness will not increase any further, and furthermore, the plasticizer component will volatilize even under high temperature conditions.

There is no escaping, and therefore it remains flexible even when used under any temperature conditions, so the object coated with this cured product will not be damaged.Moreover, the cured product has a low water absorption rate and can be used at high temperatures. Excellent electrical insulation during high humidity.

Claims (1)

[Claims] 1. Polyol component (A), polyisocyanate component (
Curing of a two-component solvent-free polyurethane system comprising B) and a plasticizer component (C), the plasticizer component (C) comprising highly acylated castor oil. sexual composition. 2. The composition according to claim 1, wherein the polyol component (A) is a high viscosity hydrocarbon polyol, castor oil or a derivative thereof. 3. The composition according to claim 2, wherein the castor oil derivative is partially acylated castor oil, partially dehydrated castor oil, or a castor oil-hydroxyl group-free natural oil or fat transesterification product. Composition according to item 1. 4. The composition according to claim 1, wherein the highly acylated castor oil constituting the plasticizer component (C) is a highly acylated castor oil having a hydroxyl value of less than 20 mgKOH/g. 5. The composition according to claim 1, which is a composition for protecting printed wiring boards.