JPS59152919A - Resin composition curable with microwave radiation - Google Patents

Abstract

PURPOSE:To provide the titled composition containing an unsaturated polyester prepolymer and diallyl phthalate, curable in a short time, and effective to energy saving. CONSTITUTION:The objective composition is prepared by mixing (A) an unsaturated polyester prepolymer obtained by the polycondensation of generally an unsaturated polybasic acid, a saturated polybasic acid and a glycol, (B) a polymerizable monomer (e.g. styrene) containing preferably 15-90% of diallyl phthalate and (C) a polymerization initiator. The polymerization initiator (C) is preferably a mixture of plural polymerization initiators (e.g. benzoyl peroxide, dicumyl peroxide) having different half-life times from each other.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to microwave curable unsaturated polyester resin compositions.

Usually, the curing reaction of thermosetting resins such as unsaturated polyester resins involves thermosetting by heating. In this method, an uncured resin composition is placed in a furnace heated to 100 to 150°C and cured, and is widely used as a method for curing thermosetting resins such as unsaturated polyester resins. .

Although curing the resin by external heating is an easy method, it has the following drawbacks.

In other words, since the heating furnace must be constantly heated, there is a lot of waste in energy consumption. In other words, since it takes a considerable amount of time to raise the temperature of the furnace, the furnace must be constantly heated, and the inner cone must be used at the appropriate time when the power is turned off. In addition, if the resin to be cured is in contact with a metal with a large heat capacity, most of the heat will be taken away by the metal with a large heat capacity even if it is put into the furnace, so it will have to be heated more than necessary. , which goes against energy conservation.

In order to solve the above-mentioned drawbacks, an internal heating method using microwaves based on the molecular motion of the resin is a convenient heating means. Microwave curing is an internal heating method, and it has long been known that it heats the resin part efficiently, but in order to cure it efficiently in a short time, it is necessary to have a resin composition suitable for microwave heating. be.

Unsaturated polyester resin, which is a commonly used thermosetting resin, is a prepolymer obtained by polycondensation reaction of glycol, unsaturated polybasic acid, and saturated polybasic acid.
A peroxide is added as a polymerization initiator to a resin composition containing a polymerizable vinyl monomer, and a polymerization reaction and a crosslinking reaction are performed by heating to form a three-dimensional structure. Conventional unsaturated polyester resin compositions mainly composed of styrene monomer and unsaturated polyester prepolymer have no heating effect with microwaves, and (i
There was a drawback that microwave heating could not be used for curing fat.

This invention was made to eliminate the drawbacks of the conventional products as described above, and by using a polymerizable monomer containing diallyl phthalate and an unsaturated polyester polymer as composition components, heating by microwaves is possible. The object of the present invention is to provide a microwave-curable resin composition that can be cured in a short time.

Generally, unsaturated polyester resin compositions include glycol,
The composition includes a prepolymer obtained by polycondensation reaction of an unsaturated polybasic acid and a saturated polybasic acid, and a polymerizable vinyl monomer.

Examples of unsaturated polybasic acids include maleic anhydride, fumaric acid, citraconic acid, and itaconic acid. Examples of saturated polybasic acids include tetrachlorophthalic anhydride, head acid, tetrabromo phthalic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, endomethylenetetrahydrophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and amber. acids, adipic acid, azelaic acid,
Examples include sebacic acid.

Examples of glycols include ethylene glycol, phlopylene gelol, butanediol 1,4, butanediol 1,3, butanediol 2゜3, diethylene glycol, cyphropylene glycol, triethylene glycol, and bentanediol 1.5. , hexanediol 1,6, neotinthyl glycol, 2,2.4 trimethyl ntandiol-1.3, hydrogenated bisphenol A
, 2.2-di(4-hydroxypropoxyphenyl)propane, R-ntaerythritol diallyl ether, glycerin, trimethylene glycol, 2-ethyl-1,3
-hexanediol, phenyl glycidyl ether, 7
1J/l/glycidyl ether, etc.

These polybasic acids and glycols are combined in an appropriate vortex, the amount of glycol is slightly excessive (approximately 10% more glycol), and a polycondensation reaction is performed at 150 to 200"C to produce a prepolymer with an acid value of 50 or less. are synthesized.

Styrene monomer is normally used as the polymerizable vinyl monomer, but in the present invention, diallylphthalate is added to enable polymerization reaction by microwave irradiation. Although diallyl phthalate may be used alone as the polymerizable vinyl monomer, it is preferable to use it in combination with a styrene monomer. In this case, the proportion of diallyl phthalate in the total polymerizable monomers is preferably 15 to 90%, preferably 25 to 80%. .

The unsaturated polyester resin composition of the present invention contains the prepolymer and these polymerizable monomers, and the composition ratio of the polymerizable monomers is 30 to 80%. The amount of polymerizable monomer added depends on the concentration of unsaturated groups in the prepolymer and the viscosity used. Such a resin composition is cured by adding an organic peroxide catalyst such as benzoyl peroxide as a polymerization initiator, and irradiating it with microwaves and heating it (generally 100 to 150 degrees O).

It is desirable to use a plurality of different types.

Microwaves are electromagnetic waves that occupy a range between radio waves and infrared waves, and have a frequency of 300 MH2 to 300 GT (z
.

The wavelength is 1 to 10'''3m, but the frequency band that can be used industrially is regulated by the Radio Law, and is 2453 to 245.
A frequency of 4 MHz can be used. When a resin composition containing a polymerization initiator is placed in such a microwave heating curing furnace and heated, the resin composition is efficiently heated.
Hardens in a short time (several minutes). Since diallylphthalate-based unsaturated polyester is rapidly heated and boiled by microwave irradiation, bumping or foaming may occur, in which case it is necessary to irradiate it with microwaves intermittently.

Figure 1 shows the results of an experiment in which diallyl phthalate monomer, styrene monomer, unsaturated polyester prepolymer (from Example 2), and water were heated in a 2453 MHz household microwave oven. This is a relationship curve diagram of temperature rise. From this result, the temperature of styrene hardly rises, but diallyl phthalate rises to 110-120°C by just irradiating it with microwave for 10 seconds.
The temperature rose to , and a significant microwave irradiation effect was observed. Therefore, when the unsaturated polyester composition contains diallyl phthalate, the temperature of the unsaturated polyester rapidly rises due to the remarkable heating effect of microwave irradiation, and the polymerization reaction due to heating proceeds. As described above, since the temperature of the unsaturated polyester composition is increased in a short time by adding the diallyl 7-thalerate monomer, it can be effectively cured by microwave heating.

However, since diallyl phthalate has a slower polymerization rate than styrene, it is necessary to raise the curing temperature to achieve the same curing conditions as styrene, which reduces the advantage of the fast temperature rise speed that can be achieved by adding diallyl phthalate. You end up doing it. On the other hand, the curing rate of unsaturated polyesters can be adjusted by increasing or decreasing the amount of peroxide, which is a polymerization initiator. Since diallyl phthalate is polymerized at a relatively high temperature, those with a long half-life are used, and dicumyl peroxide is generally used. For reference, benzoyl peroxide has a half-life of 100 hours at 53°C, while dicumyl peroxide has a half-life of 1o.

C and has a half-life of 100 hours. Unsaturated polyester using diallyl phthalate has excellent storage stability because of its long gelation time, but its curing time is longer than that of styrene, and it cannot be rapidly cured in a short period of time. For this reason, systems containing diallyl phthalate alone cannot fully utilize the characteristics of microwave heat curing.

Therefore, we mixed appropriate amounts of diallyl phthalate and styrene,
Furthermore, by using two types of initiators with different half-lives, it becomes optimal for microwave heating curing. When only diallylphthalate is used, gelation time is long, but 2
When more than 0% styrene is added, the gelation time is not significantly different from styrene alone. In an unsaturated polyester composition, if the proportion of diallyl phthalate is high, the heating effect due to microwave irradiation will be greater, but the gelation time will be longer, so it is necessary to find an appropriate amount. FIG. 2 is a relationship diagram showing the results of measurements of gelation time and heating temperature when diallyl phthalate and styrene were added to an unsaturated polyester prepolymer in various proportions.

The results show that when the proportion of diallyl phthalate is high, the temperature rises in a short time, but the gelation time becomes longer. The composition is 15 to 90% diallyl phthalate;
It can be seen that a ratio of preferably 25 to 80% is suitable.

When diallyl phthalate is added, the glass transition temperature of the resulting cured product increases by about 20°C compared to when styrene alone is used. Although the cost of diallyl phthalate is slightly higher than that of styrene, the resulting cured product has excellent thermal and mechanical properties, making it sufficiently practical.

In the above description, any combination of prepolymers can be used by selecting the respective constituent units. Furthermore, the polymerization initiator is not limited to those mentioned above.

As described above, according to the present invention, since the composition is composed of a polymerizable monomer and a prepolymer containing diallyl phthalate, it is heated by microwave heating at a considerably faster rate than conventional unsaturated polyester resins. Therefore, the curing reaction can be completed in a short time. As a result, it may come into contact with metals etc. with large heat capacity.
However, the resin part is heated quite efficiently, and unlike conventional external heating systems such as heating ovens, thermal energy is not consumed in the structure of the oven or in parts of the heating body that have a large heat capacity. In addition, in the case of microwave heating,
In order to cure the resin, if the microwave heating power is turned on each time, the temperature of the resin will rise in a short time, and there is no need to constantly heat it like in a conventional heating oven.

Next, examples of the present invention will be described.

Phthalic acid 1.119, Flopylene gelicol 251g,
Stir 1.02 g of ethylene glycol and 175!9 diethylene glycol in a fourth flask,
The reaction was carried out at 120°C, and reflux was carried out until water was produced in many ridges. While removing the produced water from the reaction system,
The reaction was continued at 0° C. to 180° C. for 2 to 3 hours, and the reaction was further carried out to the vicinity of a predetermined dehydration needle to obtain an unsaturated polyester sol polymer having an acid value of 35. 0.1 at the end of the reaction
% of no-hydroquinone was added, and the temperature of the reactant was 80°C.
When the amount was below, 130 g of styrene monomer and 5009 diallyl phthalate monomer were added and stirred thoroughly to obtain an unsaturated polyester resin composition with a solid content of 60.

As a polymerization initiator, unsaturated polyester prepolymer 1
05 parts of benzoyl .
W, 2450 Ml-1z was placed in a microwave heating furnace and treated for about 15 minutes to obtain an unsaturated polyester prepolymer. The general characteristics of the obtained cured product are: volume resistivity: 8.7 x 10”
5Ω-Brass, dielectric breakdown strength 4. ．． 5 kV/Q, lim,
The tensile strength was 6.8 kg/rni. These values are 1
It was found that the value almost coincided with that obtained by heating at 35° for 0.3 hours.

Example 2 192 g of trimellitic anhydride in 4 flasks 1 122 L of monoethanolamine 416 L of neosunthyl glycol. F, add 248g of ethylene glycol, 16
Heat to 0 to 170' 0 with stirring, add 760 g of tetrahydrophthalic anhydride, raise the temperature to 190°C while dehydrating, and add 392 g of maleic anhydride.
was added to continue the reaction, and the acid value was adjusted to 110-120. Next, it was cooled to 120'O, and 0.6g of hydroquinone and 150g of bisphenol type epoxy resin (Epon828) were added.
0g was added and the reaction proceeded at 120°C, and when the acid value reached a value of 25, 0.3g of hydroquinone, 1200g of diallyl phthalate, and 600g of styrene were added to form an unsaturated polyester resin with a solid content of 65%. I got something.

Unsaturated polyester prepolymer 10 of the resulting composition
0 parts of banzoyl peroxide as an initiator
．． 3 parts and 07 parts of dicumylno ξ-oxide were added, and this was coated on a glass plate, placed in a 5 kW 12450 MHz microwave heating furnace, and treated for about 20 minutes to obtain a cured product.

The general characteristics of the obtained cured product are a volume resistivity of 71×101
11Ω-I, dielectric breakdown strength 9.9 kV/0.1 u
m, tensile strength 7.3 degrees/rnd, ]55°0
It was found that almost the same values as those obtained by heating for 6 hours were obtained.

[Brief explanation of the drawing]

Figure 1 is a relationship diagram showing the relationship between the microwave irradiation time and temperature of the resin component, and Figure 2 is a relationship diagram showing the relationship between the composition ratio of the monomer added to the unsaturated polyester, gelation time, and temperature rise (microwave heating for 3 minutes). It is a relationship diagram showing a relationship. Agent Shin Kuzuno - (1 other person)

Claims (5)

[Claims] (1) A microwave-curable resin composition comprising, as constituent components, an unsaturated polyester prepolymer made of a condensate of acid and glycol, and a polymerizable monomer containing diallyl phthalate. (2) A microwave-curable resin composition in which the unsaturated polyester prepolymer is unsaturated. (3) The microwave-curable resin composition according to claim 1 or 2, wherein the polymerizable monomer contains styrene and diallyl phthalate. (4) The microwave-curable resin composition according to any one of claims 1 to 3, wherein the proportion of diallyl phthalate in the polymerizable monomer is 15 to 90%. (5) The microwave-curable resin composition according to any one of claims 1 to 4, wherein the #l fat composition contains a plurality of types of polymerization initiators having different half-lives. .