JPH08319336A - Production of high-purity epoxy resin - Google Patents

Abstract

PURPOSE: To obtain a high-purity epoxy resin extremely low in the content of water-soluble impurities containing α-diols etc., suitable for e.g. electronic equipment, by bringing an epoxy resin made up of a polyhydric phenol diglycidyl ether into contact with an aqueous solution of a specific compound. CONSTITUTION: This high-purity epoxy resin is obtained by bringing (A) an epoxy resin made up of a polyhydric phenol diglycidyl ether into contact with (B) an aqueous solution of a compound selected from boric acid and its salts (e.g. lithium metaborate) pref. at 50-100 deg.C for 10-30min. The component A is obtained, in general, by ring opening addition reaction between a polyhydric phenol such as bisphenol A and epichlorohydrin in the presence of a catalyst while or followed by carrying out a ring opening with an alkali metal hydroxide. The solution B contains pref. 0.1-10 wt.% of a compound selected from boric acid and its salts, and it is preferable that the amount of the solution B to be used be 0.05-0.3wt. times the component A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-purity epoxy resin, and particularly to an electric / electrical resin which requires high reliability.
The present invention relates to a method for producing a high-purity epoxy resin which is useful as a material for an electronic component encapsulant, a laminated plate, or the like, or as an epoxy resin component in a coating field requiring high mechanical properties.

[0002]

2. Description of the Related Art Generally, epoxy resins are widely used for adhesives, paints, electrical insulating materials, etc. because they are excellent in heat resistance, adhesiveness, chemical resistance, electrical properties, mechanical properties, etc. . In the conventional epoxy resin used in the above-mentioned applications, the terminal groups are not all epoxy groups, and for example, α-diol groups, hydrolyzable chlorine, functional groups such as phenolic hydroxyl groups, or polyglycerin whose structure has not been confirmed are considerably contained. It is known to include.

Among these impurities, the one which has the strongest influence on the properties of the cured product obtained by curing the epoxy resin is the α-diol group-containing compound. For example, when an epoxy resin is used for electronic materials, high heat resistance, water resistance, and chemical resistance are required to ensure circuit reliability, but the epoxy resin contains α-diol group It is known that as the amount of the compound increases, the crosslink density formed from the epoxy resin and the curing agent decreases, and the introduction of a polar group having a high degree of molecular freedom into the crosslinked structure leads to a decrease in these performances. (See Japanese Patent Publication No. 3-7205, etc.). On the other hand, when using the epoxy resin in powder coating applications, as the amount of the α-diol group-containing compound in the epoxy resin increases, the tensile strength of the coating film formed from the epoxy resin and the curing agent for the same reason as above, It has been reported that the impact resistance is remarkably reduced (Japanese Patent Laid-Open No. 59-152964).

By the way, as the epoxy resin used for the above-mentioned applications, those generally available on the market are usually
Manufactured by a one-step method or a two-step method [Hiroshi Kakiuchi, "New Epoxy Resin", Shokodo, p. 30 (Showa 60)
Year)].

The one-step method is a method in which a predetermined amount of polyhydric phenol and epichlorohydrin are reacted at once in the presence of an alkali such as sodium hydroxide and water to produce an epoxy resin. However, in this method, epichlorohydrin often undergoes a hydrolysis reaction with sodium hydroxide during the reaction, and as a result, various α-
A diol group-containing compound is produced as a by-product. Here, the α-diol group-containing compound is, for example, the following formula:

[0006]

Embedded image

In the molecules of compound (1), glycerin (2), polyglycerin (2) and the like, which are by-produced by the reaction shown in (wherein, for convenience, phenol is used as an example in the above formula). A compound having a group represented by the formula: —CH ₂ —CH (OH) —CH ₂ —OH. In fact, the content of the α-diol group in the epoxy resin obtained by such a one-step method is usually about 10 to 20 meq / 100 g, and the epoxy equivalent is about 500 bisphenol A.
In the case of the type epoxy resin, the ratio of all the terminal functional groups is about 5 to 10%.

On the other hand, the other manufacturing method, the two-step method, is
Using an excess of epichlorohydrin with respect to polyhydric phenol, reacting in the presence of alkali, once producing a low molecular weight epoxy resin, and then further reacting the low molecular weight epoxy resin and polyhydric phenol To produce a high molecular weight epoxy resin.

In this two-step process, there is an excess of epichlorohydrin in the process of producing the low molecular weight epoxy resin, and the addition (etherification) process is performed under substantially anhydrous conditions, so that glycidol is used. Is less likely to be produced, and as a result, a high molecular weight epoxy resin having a low content of terminal α-diol groups can be obtained. The content of α-diol group in the epoxy resin obtained by such a two-step method is usually about 3 to 6 meq / 100 g.

[0010]

However, conventionally, in the resin prepared by the one-step method, an α-diol group-containing compound was used in an amount of 9%.
meq / 100g or less 2 in the two-step method resin
No rational method of reducing to less than or equal to meq / 100 g was known.

Therefore, an object of the present invention is to provide a high-purity epoxy resin having a very small content of water-soluble impurities containing an α-diol group or the like, which is suitable for use in electronic devices and coatings. To provide.

[0012]

Therefore, the present inventors have made intensive studies on a method for reducing the amount of the α-diol group-containing compound in the epoxy resin. as a result,
In the case of the conventional one-step method epoxy resin, the α-diol group content is 10 (meq / 10) by an extremely simple operation of treating the epoxy resin with an aqueous solution of a specific inorganic compound.
It was found that the amount can be reduced to 0 g) or less, and in the case of the conventional two-step method epoxy resin, to less than 3 (meq / 100 g), and the present invention has been completed.

That is, the present invention provides a method for producing a high-purity epoxy resin, which comprises a step of bringing an epoxy resin composed of a diglycidyl ether of a polyhydric phenol into contact with at least one aqueous solution selected from boric acid and borate. It is provided.

The method for producing the high-purity epoxy resin of the present invention (hereinafter referred to as the "method of the present invention") will be described in detail below.

In the method of the present invention, the epoxy resin used is composed of diglycidyl ether of polyphenol. Examples of polyhydric phenols constituting this epoxy resin include monocyclic polyhydric phenols such as hydroquinone and resorcin, 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 1,1-
Bis (4-hydroxyphenyl) ethane [bisphenol AD], bis (4-hydroxyphenyl) methane [bisphenol F], bis (4-hydroxyphenyl) sulfone, 2,2-bis (3,5-dibromo-4-hydroxy) Phenyl) propane, 1- [α-methyl-α
(4'-Hydroxyphenyl) ethyl] -4- [α ',
α'-bis (4'-hydroxyphenyl) ethyl] benzene, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, phenol novolac, cresol novolac and other polycyclic poly Examples of the phenol include, but are not limited to.

In the present invention, the above-mentioned epoxy resin is subjected to ring-opening addition (etherification) reaction of the above polyhydric phenol and epichlorohydrin in the presence of a catalyst to form a chlorohydrin ether compound of polyhydric phenol. , Then, or simultaneously with etherification, by ring closure (dehydrochlorination) with an alkali metal hydroxide. In this case, generally, the hydrolyzable chlorine due to the chlorohydrin ether group remains in a part of the epoxy resin,
In order to further reduce this amount, alkali metal hydroxide is reacted to perform ring closure (redehydrochlorination) again to obtain a crude epoxy resin. After that, in general, in order to remove the trace amount of alkali metal hydroxide and by-product salt remaining in the crude epoxy resin, the crude epoxy resin is diluted with an aromatic solvent such as toluene or xylene, and then washed with water and neutralized. After the treatment and concentration of the solvent, the product epoxy resin is isolated through microfiltration.

In the method of the present invention, treatment is carried out by bringing the epoxy resin obtained as described above into contact with at least one aqueous solution selected from boric acid and borate (hereinafter referred to as "contact treatment liquid"). Is a method of purifying an epoxy resin. The treatment with the contact treatment liquid can also be performed on the above-mentioned crude epoxy resin,
The epoxy resin in a product state and a so-called two-step method resin in which the epoxy resin has a higher molecular weight by a fusion reaction with a dihydric phenol may be used.

The contact between the crude epoxy resin, the product type epoxy resin, and the contact treatment liquid is carried out by temporarily removing the epoxy resin,
A method is used in which the solvent is diluted with an aromatic solvent such as toluene or xylene, a ketone solvent such as methyl isobutyl ketone or cyclohexanone, and then contacted. The amount of solvent in the case of diluting with a solvent is not particularly limited, but generally, when the amount of the solvent is such that the solid content concentration is 70% by weight or less, the liquid separation speed after the contact treatment is fast, which is economical.

Examples of the boric acid and borate used in the contact treatment liquid in the method of the present invention include boric acid, boric anhydride, lithium metaborate, sodium metaborate, dipotassium tetraborate, lithium tetraborate. , Sodium tetraborate, potassium tetraborate and the like. These may be used alone or in combination of two or more.

The contact treatment liquid usually contains at least one selected from boric acid and a borate salt in an amount of 20% by weight or less, preferably 0.1 to 10.0% by weight.

In the method of the present invention, it is also possible to dissolve and use other inorganic compounds in the contact treatment liquid in addition to at least one selected from the above boric acid and borate. Examples of other inorganic compounds used include alkali metal salts such as sodium chloride and potassium chloride, phosphoric acid, disodium phosphate, monosodium phosphate, trisodium phosphate, dipotassium phosphate, and potassium phosphate. It is also possible to use one of these phosphates or a mixture of two or more thereof. In particular, when an aqueous solution of phosphoric acid, monosodium phosphate, monopotassium phosphate or the like is allowed to coexist with an acidic inorganic compound and brought into contact with the crude epoxy resin, the neutralizing function also works and is effective.

The temperature at which the epoxy resin and the contact treatment liquid are brought into contact with each other depends on the kind of solvent used to dilute the epoxy resin, but is usually in the range of 50 to 100 ° C. The contact time is usually about 5 minutes to 60 minutes, preferably about 10 minutes to 30 minutes.

The amount of the contact treatment liquid used is usually 0.01 to 0.5 times the weight of the epoxy resin, preferably 0.0.
It is a ratio of 5 to 0.3 times the weight. If it is 0.01 times or less by weight, there is almost no effect of reducing water-soluble impurities.
When the weight exceeds 5 times, the reduction effect becomes constant.

Further, in the method of the present invention, the contact between the solvent-diluted product of the epoxy resin and the contact treatment liquid is not particularly limited, and it can be carried out according to a general stirring / mixing method. After contacting the solvent-diluted product of the epoxy resin with the contact treatment liquid, neutralizing and washing with water if necessary, and then distilling off the solvent and passing through steps such as microfiltration. Can be obtained.

[0025]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. The epoxy equivalent, the viscosity, the amount of hydrolyzable chlorine, the amount of α-diol, and the amount of CODMn in the extracted water in the examples were measured according to the following methods.

1) Epoxy equivalent; epoxy resin 0.2 to
After precisely weighing 5 g and putting it in a 200 ml Erlenmeyer flask,
Add 25 ml of dioxane and dissolve. Add 25 ml of a 1/5 N hydrochloric acid solution (dioxane solvent), stopper tightly, mix well, and let stand for 30 minutes. Next, toluene-
After adding 50 ml of an ethanol mixed solution (1: 1 volume ratio), the mixture is titrated with 1/10 N sodium hydroxide aqueous solution using cresol red as an indicator. Based on the titration results,
Epoxy equivalent is calculated according to the following formula.

[0027]

[Equation 1]

W: sampled amount (g) B: 1/10 normal sodium hydroxide aqueous solution (ml) required for blank test S: 1/10 normal sodium hydroxide aqueous solution (ml) required for sample test N: Normality of sodium hydroxide aqueous solution F: Titer of 1/10 normal sodium hydroxide aqueous solution

2) Viscosity : After measuring specific gravity, JIS
It was determined according to K-7233. 3) Hydrolyzable chlorine content : Epoxy Resin Technical Association "Technical Report No. 1-Method for measuring the amount of saponifiable chlorine in epoxy resin"
ASTM De listed in (Published September 1972)
signation: measured according to the D1276-73 method.

4) α-diol group content : 1 to 2 g of an epoxy resin sample is precisely weighed and placed in a 300 ml iodine flask, and 25 ml of chloroform is added to completely dissolve it. Then, 25 ml of a 1/5 normal benzyltriethylammonium periodate methanol solution was added and mixed, and then the mixture was allowed to stand at room temperature for 2 hours. After 100 ml of cold water was added and mixed vigorously, 5 ml of (1 + 10) sulfuric acid and 20 ml of 20% potassium iodide aqueous solution were added and thoroughly mixed, and then 1 /
Titrate with 10N aqueous sodium thiosulfate solution until the iodine is gone. A blank test is conducted in parallel, and the α-diol group content is determined by the following calculation formula.

[0031]

[Equation 2]

B: 1/10 normal sodium thiosulfate aqueous solution consumed in blank test (ml) S: 1/10 normal sodium thiosulfate aqueous solution consumed in sample test (ml) N: Normality of sodium thiosulfate aqueous solution F: titer of 1/10 normal sodium thiosulfate aqueous solution W: sampling weight of epoxy resin (g)

Reference Example 1 Bisphenol A and epichlorohydrin were subjected to a ring-opening reaction at a charged molar ratio of 1:10, and sodium hydroxide was subsequently added to carry out a dehydrochlorination reaction. After completion of the reaction, unreacted epichlorohydrin was distilled off under reduced pressure. Then, sodium chloride produced as a by-product was washed and removed to obtain an epoxy resin containing 0.8% by weight of hydrolyzable chlorine. Then, 2.5 times equivalent of 6 wt% sodium hydroxide aqueous solution was added to the hydrolyzable chlorine, and dehydrochlorination reaction was performed again at 95 ° C. Further, toluene was added to the reaction mixture so that the solid concentration was 50% by weight.
After the addition, the liquid was separated. The upper layer portion of the separated toluene solution was treated with the following Examples 1-3 and Comparative Examples 1-2.
Used as a raw material resin.

Reference Example 2 An epoxy resin was produced in the same manner as in Reference Example except that the charged molar ratio of bisphenol A and epichlorohydrin was 1: 2. The amount of hydrolyzable chlorine was 0.0 when the by-product sodium chloride was removed by washing with water.
Since it was 03% by weight, xylene was added thereto so that the solid content concentration became 50% by weight, and the following Examples 4 to 5 were performed.
And used as a raw material resin in Comparative Example 3.

Examples 1 to 3 To the toluene solution of the epoxy resin obtained in Reference Example 1, the boric acid or borate aqueous solution shown in Table 1 was added, and the mixture was stirred and mixed at 80 ° C. for 15 minutes. After standing, the separated water layer was removed, toluene was distilled off from the organic layer under reduced pressure, and filtration was performed to obtain a purified epoxy resin. The epoxy equivalent, α-diol group content, viscosity, softening point and hydrolyzable chlorine content of this purified epoxy resin were measured. The results are shown in Table 1.

(Examples 4 to 5) To the xylene solution of the epoxy resin obtained in Reference Example 2, the boric acid or borate aqueous solution shown in Table 1 was added and mixed with stirring at 90 ° C for 15 minutes. After standing, the separated water layer was removed, toluene was distilled off from the organic layer under reduced pressure, and filtration was performed to obtain a purified epoxy resin. The epoxy equivalent, α-diol group content, viscosity, softening point and hydrolyzable chlorine content of this purified epoxy resin were measured. The results are shown in Table 1.

(Comparative Example 1) Epoxy resins were isolated in the same manner as in Examples 1 to 3 except that the contact treatment with the aqueous solution of boric acid or borate was not carried out. Epoxy equivalent of the obtained epoxy resin, α-
The diol group content, viscosity, softening point and hydrolyzable chlorine content were measured. The results are shown in Table 1.

Comparative Example 2 The epoxy resin was isolated in the same manner as in Examples 4 to 5 except that the contact treatment with the aqueous solution of boric acid or borate was not performed in Examples 4 to 5. Epoxy equivalent of the obtained epoxy resin, α-
The diol group content, viscosity, softening point and hydrolyzable chlorine content were measured. The results are shown in Table 1.

[0039]

[Table 1]

Example 6 The epoxy resin 254.9 obtained in Example 1 was placed in a 500 ml separable flask equipped with a stirring blade, a thermometer, a nitrogen inlet, and a cooling tube.
g, tetrabromobisphenol A 145.1 g and xylene 80 ml were charged and the temperature was raised under a nitrogen atmosphere. When the internal temperature reached 80 ° C., 0.8 g of a 1 wt% tetramethylammonium chloride aqueous solution was added, and the temperature was further raised. When the internal temperature reached 130 ° C., the pressure inside the reaction system was reduced and xylene and water were taken out of the system. The reaction was carried out while maintaining the reaction temperature at 150 ° C., and after 1 hour, the inside of the reaction system was returned to normal pressure with nitrogen. Further 150
After continuing stirring at ℃ for 4 hours, the reaction mixture was cooled to about 70 ℃ and diluted with 133 g of methyl ethyl ketone to obtain a solvent-diluted epoxy resin. The properties of the solvent-diluted epoxy resin obtained were as follows. Solid content concentration: 75.3 wt% Viscosity: 470 cps / 25 ° C. Resin equivalent epoxy equivalent; 493 g / eq Resin equivalent bromine content: 21.0 wt% Resin equivalent α-diol group content: 1 meq / 100 g
The amount of hydrolyzable chlorine in terms of resin below: 0.013% by weight

Example 7 In a 1000 ml separable flask equipped with a stirring blade, a thermometer, a nitrogen inlet, and a cooling tube, 732 g of the epoxy resin obtained in Example 5 was added.
68 g of bisphenol A and 1500 ml of xylene were charged and the temperature was raised under a nitrogen atmosphere. When the reaction mixture was homogenized and the internal temperature reached 100 ° C., 1.6 g of xylene solution of triphenylphosphine (5 wt%) was added.
Was added and the temperature was further raised. When the internal temperature reached 130 ° C, the pressure inside the reaction system was reduced, and xylene was taken out of the system. Next, the reaction was performed while maintaining the reaction temperature at 160 ° C., and 1 hour later, nitrogen was introduced into the reaction system to return the pressure inside the reaction system to normal pressure. Furthermore, after continuing stirring at 160 ° C. for 6 hours, the reaction mixture was extracted. The properties of the obtained epoxy resin were as follows. Softening point; 94 ° C., epoxy equivalent; 930 α-diol group content; 1 meq / 100 g amount of hydrolyzable chlorine; 0.002% by weight

(Comparative Example 3) In Example 6, in Example 1
In the same manner as in Example 6 except that the epoxy resin obtained in Comparative Example 1 was used instead of the epoxy resin obtained in 1.
A solvent diluted epoxy resin was obtained. The property values of the obtained epoxy resin were as follows. Solid content concentration: 74.8% by weight Viscosity: 490 cps / 25 ° C. Resin equivalent epoxy equivalent: 494 Resin equivalent bromine content: 21.0% by weight Resin equivalent α-diol group content: 5 meq / 100 g Resin equivalent water Degradable chlorine amount: 0.013% by weight

Comparative Example 4 In Example 7, Example 5
An epoxy resin was obtained in the same manner as in Example 7 except that the epoxy resin obtained in Comparative Example 3 was used instead of the epoxy resin obtained in 1. The property value of the obtained epoxy resin is
It was as follows. Softening point: 93 ° C. Epoxy equivalent: 929 α-diol group content: 14 meq / 100 g Hydrolyzable chlorine content: 0.003% by weight

133 g of each of the methyl ethyl ketone diluted epoxy resins obtained in Example 6 and Comparative Example 3, 27 g of a dicyandiamide methylcellosolve / DMF solution (dicyandiamide concentration = 12% by weight), and a benzyldimethylamine methylethylketone solution (concentration = 10% by weight). %) 0.18 ml were uniformly mixed to obtain two kinds of epoxy resin compositions. Each of these two kinds of epoxy resin compositions was mixed with glass cloth (WE-18K-B
Z2) was impregnated and heated at 150 ° C. for 5 minutes to prepare a prepreg. 170 pieces of this prepreg are piled up
The laminate was heated and pressed for 60 minutes at a temperature of 10 ° C. and 10 kgf / mm ² to produce a laminated plate having a thickness of 1.6 mm. The obtained laminated plate was boiled for 5 hours to absorb water, and then placed in a solder bath at 260 ° C for 3 hours.
It was immersed for 0 seconds and examined for abnormalities such as "peeling" and "measling". As a result, no abnormality was found in the laminated plate produced using the methyl ethyl ketone diluted epoxy resin obtained in Example 6, but Comparative Example 3
It was found that "measling" and "blister" were generated on the entire surface of the laminated plate prepared by using the epoxy resin diluted with methyl ethyl ketone obtained in 1.

100 g each of the epoxy resins obtained in Example 7 and Comparative Example 4 and a curing agent dicyandiamide 4
g, 50 g of rutile type titanium oxide as a filler, and 1.2 g of acrylic resin as a flow adjusting agent, and the mixture was pulverized and mixed by a pulverizer and then heated to 105 ° C.
It was kneaded for 8 minutes with a two-inch roll. After cooling the kneaded material,
It was crushed with a hammer mill and a powder having a particle size of 150 to 250 mesh as a main component was prepared with a standard sieve.

This powder was preliminarily applied to 1 by using an electrostatic coating machine.
Iron plate with a thickness of 9 mm heated to 80-200 ° C (SS-4
1, # 120 sander polishing) and apply at 200 ° C for 10
By performing post cure for about 3 minutes, the film thickness is about 300.
A coating film of ˜350 μ was obtained. With respect to this coating film, a 2 kg weight was dropped at a room temperature of 5/8 inch using a DuPont impact tester. As a result, regarding the coating film obtained by using the epoxy resin obtained in Example 7,
50 cm or more, while the coating film obtained using the epoxy resin obtained in Comparative Example 4 was 25 cm.

[0047]

According to the method of the present invention, it is possible to obtain a high-purity epoxy resin having a very small content of water-soluble impurities containing an α-diol group or the like. Therefore, the high-purity epoxy resin obtained by the method of the present invention is suitable for use in electronic devices and coatings.

Claims (1)

[Claims] 1. A method for producing a high-purity epoxy resin, which comprises a step of bringing an epoxy resin composed of a diglycidyl ether of a polyhydric phenol into contact with an aqueous solution of at least one selected from boric acid and borate.