JP2770198B2 - Method for producing modified epoxy resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application >> The present invention relates to a method for producing a modified epoxy resin. More specifically, the present invention has excellent flexibility obtained by subjecting a secondary hydroxyl group of an epoxy resin to ring-opening polymerization of a lactone compound such as ε-caprolactone, and has excellent reactivity with a crosslinking agent. And a method for producing a modified epoxy resin having a primary hydroxyl group.

Epoxy resins, particularly glycidyl ether type epoxy resins produced from bisphenol A and epichlorohydrin, are available in various varieties from liquid to high molecular weight solid resins, and are used for various applications.

Among them, low molecular weight liquid ones are cured at ordinary temperature with polyamine or polyamide resin by utilizing the reactivity of the epoxy group, and used for adhesives, FRP, flooring materials, etc. It is mainly used for electrical applications, such as cast products, by being cured by heating.

On the other hand, those having a high molecular weight are fragile solid resins having a melting point of 60 to 150 ° C. and having secondary hydroxyl groups in addition to terminal epoxy groups, so that they are used in various coating fields utilizing the reaction of the hydroxyl groups. Have been.

For example, epoxy esters esterified with unsaturated fatty acids are used in air-drying, room-temperature-drying paints, baking paints using melamine resin as a cross-linking agent, and even coatings for cans combined with phenolic resins. .

It is also used in epoxy powder coatings by mixing the powder with a blocked isocyanate.

 It is also used for cationic electrodeposition paints.

<< Prior Art >> In the conventional method for producing a modified epoxy resin, first, a bisphenol is added to a low-molecular epoxy resin (bisphenol type or hydrogenated bisphenol type) as a first-stage reaction, and an epoxy resin having a hydroxyl group in the molecule is added. Was synthesized as a second-stage reaction to synthesize a lactone-modified epoxy resin by polymerizing the lactone compound.

That is, in the technique disclosed in JP-A-63-179918, the first-stage reaction is carried out at 170 ° C. using a basic catalyst.
The second-stage reaction is continued for 7 hours, and the modified epoxy resin is obtained.

<< Problems to be Solved by the Invention >> However, in the above-described two-stage reaction, the lactone compound must be added after checking the progress of the first-stage reaction in addition to the reaction time required for each reaction.

Therefore, there is a problem that the total reaction time is considerably long, such as the time required for the check, the addition time of the lactone compound, and the time required for raising the temperature because the reaction solution temperature temporarily drops when the lactone compound is added. is there.

In addition, there is a problem that the lactone compound must be added to the high-temperature reaction solution, which makes the operation difficult.

<< Object of the Invention >> The present invention relates to a method for easily producing a lactone-modified epoxy resin for the purpose of shortening the reaction time and simplifying the operation in the above-mentioned conventional technology.

<< Means for Solving the Problems >> The method for producing the modified epoxy resin of the present invention will be specifically described.

In the method for producing a modified epoxy resin of the present invention, the following reactions (A) and (B) are carried out simultaneously in the same reaction step.

Reaction (A): a low-molecular bisphenol-type epoxy resin or a low-molecular hydrogenated bisphenol-type epoxy resin,
Reaction to add bisphenols or hydrogenated bisphenols.

Reaction (B): A reaction in which a lactone compound is subjected to ring-opening polymerization with a hydroxyl group in the epoxy resin obtained in the reaction (A).

The low-molecular bisphenol-type epoxy resin (or hydrogenated bisphenol-type epoxy resin) used in the present invention has the following structure.

Further, bisphenols or hydrogenated bisphenols have the following structures.

The lactone compound has the following structure.

[R ₁ and R ₂ are H or a C _{1 to} C ₄ alkyl group, an aryl group, an arylene group, n = 3 to 9] A catalyst is a basic catalyst for adding a bisphenol, and a catalyst for adding a lactone compound. Two types of catalysts are used.

Examples of the basic catalyst include tertiary amines such as triethylamine, dimethylbenzylamine and pyridine; quaternary amine salts such as tetramethylammonium chloride; alkali metal hydroxides such as lithium hydroxide and sodium hydroxide; and alkali metals such as lithium chloride. Salts and the like are used.

Examples of the catalyst for the lactone compound addition reaction include titanium compounds such as tetrabutyl titanate, tetrapropyl titanate, and tetraethyl titanate; organic tin compounds such as tin octylate, dibutyltin oxide and dibutyltin laurate; Stannous, stannous iodide and the like can be used.

The proportion of the lactone moiety in the lactone-modified epoxy resin obtained by the production method of the present invention is 3 to 9 per 100 parts by weight in total.
5 parts by weight, preferably 5 to 70 parts by weight are used.

The reason is that if the amount is too small, the intended flexibility cannot be obtained, and if the amount is too large, the resin becomes too soft.

The molar ratio between the low-molecular epoxy resin and the bisphenol is 2
One to one to one is used.

This is a theoretical value for preventing unreacted low-molecular epoxy resin from remaining.

As the low-molecular epoxy resin, those having an epoxy equivalent of 150 to 230 are used, but those having an epoxy equivalent of less than 150 are not commercially available, and those having an epoxy equivalent of more than 230 are not liquid but solid resins and do not satisfy the object of the present invention.

The reaction is carried out at a temperature of 80 to 240 ° C, preferably 100 to 230 ° C.

When the temperature is lower than 80 ° C., the reaction rate is low. When the temperature is higher than 240 ° C., the lactone compound such as ε-caprolactone boils and escapes out of the reaction system.

The catalyst concentration is 0.01 to 2000 ppm, preferably 0.1 to 2000 ppm, based on the total weight of the epoxy resin, bisphenol (or hydrogenated bisphenol) and the lactone compound.
The reaction is carried out at 0.01 to 1000 ppm, preferably 0.2 to 500 ppm for the lactone addition catalyst.

The reaction may be carried out without a solvent or in a solvent having no active hydrogen such as toluene or xylene.

However, a solvent having an ester bond is generally not preferred. This is because, during the reaction, transesterification occurs with the ester group in the polylactone, and polylactone not bonded to the epoxy resin may be generated.

The reaction is preferably performed in an N ₂ gas atmosphere.

 The reason is to prevent coloring of the resin.

The addition of the raw materials may be performed all at once, or the epoxy resin, bisphenols, and lactone may be charged for a more uniform reaction. Good.

The end point of the reaction is confirmed by sequentially monitoring the epoxy equivalent and the concentration of the remaining lactone compound. However, since the disappearance rate of the lactone compound is slower, only the concentration of the remaining lactone compound may be monitored.

When the epoxy equivalent and the concentration of the residual lactone compound fall within a predetermined range, the temperature rise is stopped and the product is obtained as it is.

Hereinafter, the lactone-modified epoxy resin of the present invention will be described with reference to examples, but the present invention is not limited thereto.

 In the examples, parts mean parts by weight.

Example 1 A four-necked flask equipped with a nitrogen inlet tube, a thermometer, a cooling tube, and a stirrer was charged with 1000 parts of Epicoat 828 (Yukaka Shell), 300 parts of bisphenol A, and 1300 parts of ε-caprolactone, and heated to 120 ° C. After warming, the pressure inside the system was reduced to remove water. 0.13 parts of Me ₄ NCl (tetramethylammonium chloride) and tetrabutyl titanate under a nitrogen atmosphere
0.026 parts was added and reacted at 170 ° C. for 8 hours.

The properties of the obtained epoxy resin were as shown in Table 1.

Without vacuum operation in Example 1 was repeated except the reaction was a Me ₄ NCl to 0.065 parts.

The results of the characteristic values of the obtained epoxy resin are as shown in Table 1.

Comparative Example 1 The same apparatus as in Example 1 was charged with 1000 parts of Epicoat 828 and 300 parts of bisphenol A, and the temperature was raised to 120 ° C. Then, the pressure in the system was reduced to distill off water.

Under a nitrogen atmosphere, 0.13 parts of Me ₄ NCl was added, and the reaction was carried out at 170 ° C. for 1 hour.

 The epoxy equivalent at this stage was 488 g / equivalent.

Subsequently, 1300 parts of ε-caprolactone and TE 0.026 parts of trabutyl titanate was added, and the reaction was further continued at 170 ° C. for 9 hours to obtain a modified epoxy resin.

 Table 1 shows the properties of the obtained epoxy resin.

Comparative Example 2 The same operation as in Comparative Example 1 was repeated except that Me ₄ NCl was changed to 0.065 parts and 3
The addition reaction of bisphenol was performed in a time.

The epoxy equivalent at this stage was 463 g / equivalent. Subsequently, 1300 parts of ε-caprolactone and 0.026 part of tetrabutyl titanate were added, and the reaction was further continued at 170 ° C for 9 hours to obtain a modified epoxy resin.

The results of the characteristic values of the obtained epoxy resin are as shown in Table 1.

This comparative example shows that there is no difference between the properties of the epoxy resin obtained by two-stage charging and the epoxy resin obtained by the batch charging method.

It also shows that the batch charging method has a shorter reaction time than the two-stage charging.

Claims (2)

(57) [Claims] 1. A low-molecular bisphenol-type epoxy resin having an epoxy equivalent of 150 to 230 or a low-molecular hydrogenated bisphenol-type epoxy resin, and bisphenols or hydrogenated bisphenols, and a lactone compound are charged all at once. Reaction (A): Reaction and reaction (B) for adding bisphenols or hydrogenated bisphenols to a low-molecular bisphenol epoxy resin or a low-molecular hydrogenated bisphenol epoxy resin Reaction (B): Reaction (A) ). A method for producing a modified epoxy resin, comprising simultaneously performing ring-opening polymerization of a lactone compound with a hydroxyl group in the epoxy resin obtained in the same reaction step to synthesize a lactone-modified epoxy resin. 2. Coexistence of a basic catalyst for addition of bisphenol A and a catalyst for addition of lactone,
The production method according to claim 1, wherein two reactions of bisphenol A addition and lactone addition are simultaneously performed.