JP2007056089A - Method for producing purified epoxy resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing impurities which are formed as by-products when an epoxy resin is produced. <P>SOLUTION: This method for producing the purified epoxy resin scarcely containing the gel-like impurities comprises reacting a compound having two or more atoms of active hydrogen per mol on average with an epihalohydrin in the presence of an alkali metal hydroxide, so as to obtain a crude epoxy resin containing the gel-like impurities, adding water to the obtained resin in a molten state or a solution state, mixing them, then separating the mixture into an organic layer and an aqueous layer, and further removing the gel-like impurities floating between the organic layer and the aqueous layer, so that the purified epoxy resin is produced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a purified epoxy resin that efficiently and stably removes a gel-like impurity that is produced as a by-product with the production of a high-purity epoxy resin useful in the field of electrical and electronic fields.

Epoxy resins are used in a wide range of fields such as adhesion, casting, sealing, lamination, molding and painting because of their excellent cured properties and ease of handling.
2. Description of the Related Art Conventionally, epoxy resins used for sealing and adhesion of electrical and electronic components are required to have a small amount of halogen contained as impurities therein. That is, it is known that the halogen in the epoxy resin that is ionized by hydrolysis adversely affects the electrical insulation or corrodes the lead wire or the like. In particular, when epoxy resin is used as a resin for encapsulants in semiconductor integrated circuits, a small amount of halogen is an essential condition, and as the degree of integration of semiconductor circuits increases, the allowable amount of halogen decreases. Yes.
The most widely used epoxy resins are generally produced from an active hydrogen compound having a phenolic hydroxyl group, an alcoholic hydroxyl group, a carboxyl group, a primary or secondary amine group, and an epihalohydrin. This type of epoxy resin contains an organic halogen present as an impurity, such as an inorganic halogen, a 1,2-halohydrin group, a 1,3-halohydrin group, or a halomethyl group.
Of these impurity halogens, inorganic halogen can be reduced to a level that does not cause problems with techniques such as washing with water, but other organic halogens are reduced while suppressing side reactions such as polymerization of epoxy groups sufficiently low. It is difficult to make it.

In order to produce an epoxy resin with a low content of organic halogen impurities, it is possible to improve the selectivity of the reaction by using an aprotic polar solvent or the like during the reaction between the active hydrogen compound and epihalohydrin, thereby suppressing the generation of impurities. It has been proposed (Patent Documents 1, 2, 3, 4). However, the recent strict requirements cannot be met by the effects of these methods.
Many proposals have also been made for a method of reducing the halogen content by repurifying the epoxy resin once produced. These methods hydrolyze the impurity organic halogen with a basic compound to form a halogen ion, and then remove it by washing or the like. Reaction occurs, and a large amount of gel-like impurities are generated.
For example, a method is disclosed in which an epoxy resin is dissolved in an aprotic polar solvent, and an alkali metal hydroxide is added to hydrolyze the impurity organic halogen (Patent Documents 5, 6, 7, 8, 9, 10). . However, these methods can decompose the impurity organic halogen, but generate a large amount of gel impurities.
The gel-like impurities cause problems such as clogging and defects in the cured product when using the epoxy resin, so it is necessary to completely remove the gel-like impurities. Conventionally, it has been a general technique to remove by filtration. However, since gel-like impurities are usually sticky, the filter medium (filter paper, wire mesh, etc.) is likely to be clogged, which is a difficult operation. In order to meet the increasingly demanding quality requirements in recent years, it is necessary to reduce the opening of the filter medium, and this problem has become serious. In particular, an efficient removal method has been demanded in large-scale industrial production.
In addition, epoxy resins produced from biphenols, which are frequently used in sealing materials in recent years, tend to have strong adhesion of gel-like impurities due to their chemical structure. As a result of crystallization, the above problem is further exacerbated.
JP 58-189223 A JP-A-60-31516 JP 60-31517 A JP-A-1-66224 JP 62-18778 JP 62-235314 A JP 63-174981 A Japanese Unexamined Patent Publication No. 1-126320 JP-A-2-47129 JP-A-5-17464

  The present invention relates to a method for producing a purified epoxy resin that efficiently and stably removes gel-like impurities that are by-produced when producing an epoxy resin.

As a result of various studies to solve the above-mentioned problems, the present inventors have achieved the object by using a specific separation method.
That is, the manufacturing method of the refinement | purification epoxy resin of this invention contains the following each invention.
[1] A method for producing a purified epoxy resin with little gel impurities, which is obtained by reacting a compound having an average of 2 or more active hydrogens per molecule with an epihalohydrin in the presence of an alkali metal hydroxide. The resulting crude epoxy resin containing gel-like impurities is mixed with water in a molten or solution state, then separated into an organic layer and an aqueous layer, and then the gel-like impurities floating between the organic layer and the aqueous layer are removed. A method for producing a purified epoxy resin comprising removing the epoxy resin.
[2] A step of dissolving a crude epoxy resin containing an organic halogen impurity in an organic solvent other than an epihalohydrin which dissolves the epoxy resin but is incompatible with water, and subsequently, an alkali metal hydroxide is solidified in the solution. A step of adding a solution to perform a low chlorination reaction, a step of separating the organic layer and the aqueous layer in the presence of water, and a step of removing gel-like impurities floating between the organic layer and the aqueous layer are sequentially performed. The method for producing a purified epoxy resin according to [1], which is characterized by the following.
[3] The compound having an average of two or more active hydrogens per molecule is at least one compound selected from polyphenol compounds, amino compounds and aminophenols [1] or [1] [2] A method for producing a purified epoxy resin according to [2].
[4] The purification according to any one of [1] to [3], wherein the compound having an average of 2 or more active hydrogens per molecule is a compound containing at least one biphenol Production method of epoxy resin.
[5] The method for producing a purified epoxy resin according to any one of [1] to [4], wherein the saponifiable chlorine content in the obtained epoxy resin is 500 ppm or less.
[6] The method for producing a purified epoxy resin according to any one of [1] to [5], wherein the pH of the aqueous layer is 5 or more.
[7] The method for producing a purified epoxy resin according to any one of [1] to [6], wherein the temperature for performing the operation of removing the gel impurities is 20 ° C to 150 ° C.

  The method for producing a purified epoxy resin according to the present invention can efficiently and stably remove gel impurities produced as a by-product when producing an epoxy resin, and thus can be advantageously used in the production of a high-purity epoxy resin. .

In the method for producing a purified epoxy resin, the present invention comprises mixing water in a molten state or in a solution state with an epoxy resin containing gel-like impurities by-produced in each step of producing the epoxy resin, and then mixing the organic layer and the water. This is a method for producing a purified epoxy resin, characterized in that it is separated into layers, and subsequently gel-like impurities floating between the organic layer and the aqueous layer are removed. In order to separate the organic layer and the aqueous layer, water may be added and mixed and then allowed to stand.
The epoxy resin used in the method for producing a purified epoxy resin of the present invention is an epoxy resin obtained by subjecting a compound having an average of 2 or more active hydrogens per molecule and an epihalohydrin to a condensation reaction in the presence of an alkali metal hydroxide. Is.
Examples of the active hydrogen compound used as the raw material include various phenols such as bisphenol A, bisphenol F, bisphenol AD, biphenol, tetramethylbiphenol, hydroquinone, methylhydroquinone, dibutylhydroquinone, resorcin, methylresorcin, dihydroxydiphenyl ether, and dihydroxynaphthalene. , Phenol novolac resins, cresol phenol novolac resins, bisphenol A novolac resins, phenol aralkyl resins, terpene phenol resins, dicyclopentadiene phenol resins, biphenyl phenol resins, various phenol resins, various phenols, and hydroxybenzaldehyde , Crotonaldehyde, glyoxal and other aldehydes Various phenolic compounds of such resulting polyhydric phenol resin, diaminodiphenylmethane, aminophenol, various amino compounds, such as xylene diamine, methylhexahydrophthalic hydroxy phthalic acid, and the like various carboxylic acids such as dimer acid.
Among various active hydrogen compounds, polyhydric phenol compounds, which are used as raw materials for epoxy resins widely used in the electrical and electronic field, are preferred, especially for biphenol-type epoxy resins that are used in advanced sealing materials and require strict impurity management. Biphenols as raw materials are preferred. In addition, amino compounds and aminophenols that easily generate a large amount of gel impurities during epoxy production are also preferred as active hydrogen compounds to which the impurity removal method of the present invention is applied.

Although the reaction between the active hydrogen compound and epihalohydrin as described above (hereinafter referred to as glycidylation reaction) can be performed by a known method, typical examples are described in detail below. First, the active hydrogen compound is dissolved in an amount of epihalohydrin corresponding to 3 to 20 mol per mol of active hydrogen to obtain a uniform solution. Next, while stirring the solution, 0.9 to 2 mol amount of alkali metal hydroxide per mol of active hydrogen is added as a solid or an aqueous solution to react. This reaction can be carried out under normal pressure or reduced pressure, and the reaction temperature is usually about 30 to 105 ° C. in the case of reaction under normal pressure and about 30 to 80 ° C. in the case of reaction under reduced pressure. is there. During the reaction, the reaction liquid is azeotroped while maintaining a predetermined temperature as necessary, and the condensate obtained by cooling the vaporized vapor is separated into oil / water, and the oil content excluding moisture is added to the reaction system. The reaction system is dehydrated by the returning method. Addition of the alkali metal hydroxide is carried out little by little intermittently or continuously over 1 to 8 hours in order to suppress a rapid reaction. The total reaction time is usually about 1 to 10 hours.
Epichlorohydrin or epibromohydrin is usually used as the epihalohydrin in this glycidylation reaction, and NaOH or KOH is usually used as the alkali metal hydroxide.
In this reaction, quaternary ammonium salts such as tetramethylammonium chloride and tetraethylammonium bromide; tertiary amines such as benzyldimethylamine and 2,4,6- (trisdimethylaminomethyl) phenol; 2-ethyl Catalysts such as imidazoles such as -4-methylimidazole and 2-phenylimidazole; phosphonium salts such as ethyltriphenylphosphonium iodide; phosphines such as triphenylphosphine may be used.
Furthermore, in this glycidylation reaction, alcohols such as methanol, ethanol and 2-propanol; ketones such as acetone and methyl ethyl ketone; ethers such as dioxane and ethylene glycol dimethyl ether; aprotic polarities such as dimethyl sulfoxide and dimethylformamide An inert organic solvent such as a solvent may be used.

After completion of the glycidylation reaction, removing the unreacted epihalohydrin and solvent by distillation under reduced pressure or the like yields the desired epoxy resin, but usually the epoxy resin produced by the polymerization of epihalohydrin or epoxy resin, or general organic resin Gel-like impurities insoluble in the solvent are mixed in the epoxy resin.
Next, when the amount of saponifiable halogen in the epoxy resin obtained as described above is too large, it is necessary to re-process to obtain a low chlorinated epoxy resin having a sufficiently reduced amount of saponifiable halogen. That is, the high chlorine epoxy resin is redissolved in an inert organic solvent such as 2-propanol, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, dioxane, propylene glycol monomethyl ether, dimethyl sulfoxide, and the alkali metal hydroxide is dissolved. After adding a solid, aqueous solution or alcohol solution and re-ringing reaction at a temperature of about 30 to 120 ° C. for 0.5 to 8 hours, excess alkali metal hydroxide or by-product salt is removed by washing or the like. Further, when the organic solvent is removed by distillation under reduced pressure, a low chlorinated epoxy resin is obtained. In general, the saponifiable chlorine content of an epoxy resin used in the electric / electronic field is preferably 500 ppm or less, and more preferably 200 ppm or less.
Also in this re-ring closure reaction, gel-like impurities are generated by polymerization of epoxy groups. The amount produced increases with stringent reaction conditions (excess alkali, high reaction temperature, long reaction time, etc.) in order to obtain a lower saponifiable chlorine content.

The method for producing a purified epoxy resin according to the present invention comprises mixing a crude epoxy resin containing gel-like impurities produced as described above with water in a molten state or in a solution state, and then separating the mixture into an organic layer and an aqueous layer. Subsequently, the manufacturing method is characterized in that gel-like impurities floating between the organic layer and the aqueous layer are removed.
As a solvent in the case of performing this operation in a solution state, a solvent that dissolves the epoxy resin but is incompatible with water is used. As the solvent, ketones such as methyl isobutyl ketone and cyclohexanone; aromatics such as toluene and xylene; chlorinated solvents such as epichlorohydrin and chloroform are used. The concentration of the epoxy resin is usually 10% by weight or more, preferably 20% by weight or more. If the concentration is too low, the volume increases and a large apparatus is required, which is uneconomical. This operation is most preferably carried out in a solution state of 20 to 50% by weight from the viewpoint of the ease of layer separation and viscosity.
The temperature at which this operation is performed is usually 20 to 150 ° C, preferably 30 to 120 ° C. If the temperature is too low, layer separation hardly occurs, and if it is too high, problems such as decomposition of the epoxy resin occur. The amount of water is usually preferably 20 to 300% by volume of the organic layer. If the amount of water is too small, the separation operation is difficult to perform, and if it is too large, the volume increases and a large apparatus is required, which is uneconomical. As the quality of water, higher purity is preferable. That is, the electrical conductivity (25 ° C.) is preferably 10 mS / m or less, more preferably 1 mS / m or less. If the purity of the water is poor, layer separation may be difficult to occur, and ionic impurities in the final product may increase.

The mixing time of the organic layer and water is usually 1 to 120 minutes, preferably 5 to 60 minutes. If the mixing time is too short, separation of the gel-like impurities hardly occurs, and if the mixing time is too long, the effect is not improved, and layer separation may not easily occur. The mixing method is not particularly specified, and it is sufficient that the organic layer and the aqueous layer are sufficiently mixed and the gel impurities can be separated. In general, stirring with a rotary blade is performed, but a method such as rapid addition or rapid passage through a narrow flow path may be used.
The separation time is the time necessary for sufficiently separating the organic layer, the aqueous layer and the intermediate layer of gel impurities, and in each case various conditions (type of solvent, concentration) so that the time is as short as possible. , Temperature, pH, etc.) need to be adjusted. The pH of the aqueous layer is usually preferably 5 or more, more preferably 6-12. If the pH is too low, problems such as decomposition of the epoxy resin occur. If it is too high, layer separation may not occur easily. In order to adjust pH, a small amount of a weak acid such as phosphoric acid, monosodium phosphate, oxalic acid, acetic acid, or carbonic acid may be added to the aqueous layer. The separation operation is generally performed in a stationary state where stirring is stopped, but may be performed while continuing gentle mixing. Also, a method such as centrifugation can be employed.
After the layer separation, the gel impurity layer is removed. As the method, the gel-like impurity layer may be extracted after extracting the organic layer or the aqueous layer from the upper part or the lower part of the container, or only the gel-like impurity layer may be extracted from the middle part of the container.

The method for removing the gel-like impurities used in the method for producing a purified epoxy resin of the present invention may be carried out independently, but it is preferable in terms of efficiency to carry out the method during the production of the epoxy resin. Examples of the timing for removing the gel impurities include an epihalohydrin solution after the glycidylation reaction, a molten state after removing the unreacted epihalohydrin, a solution after the recyclization reaction, and a molten state after removing the final solvent. From the standpoint of efficiency, it is preferably carried out together with the removal operation of the water-soluble impurities as a solution after the recyclization reaction. When this washing operation is repeated in batch mode, the organic layer is taken out leaving the gel impurity layer in the container and sent to the next step, and the gel impurity layer can be extracted together with the next batch. it can.
In particular, in applications where reduction of gel-like impurities is strictly required, fine gel-like impurities can be removed by further filtration after removing the gel-like impurities by the impurity removal method of the present invention. Filtration after removing 50% by weight or more, preferably 70% by weight or more of the gel-like impurities by the impurity removal method of the present invention is preferable in order to prevent clogging of the filtration membrane.

Below, the manufacturing method of the refinement | purification epoxy resin of this invention is further explained in full detail, giving an Example and a comparative example.
<Example 1>
A 2-liter three-necked flask equipped with a thermometer, stirrer, and condenser is charged with 121 g of tetramethylbiphenol and 555 g of epichlorohydrin, heated to 90 ° C. and dissolved, and then 48.5% by weight of sodium hydroxide. 82.5 g of an aqueous solution was added dropwise over 1 hour. Meanwhile, the reaction liquid is azeotroped while maintaining the temperature of the reaction liquid at 95 ° C. or higher, the condensate obtained by cooling the vaporized vapor is separated into oil / water, and the oil component excluding moisture is returned to the reaction system. It dehydrated from the reaction system by the method. Even after completion of the dropwise addition of the aqueous sodium hydroxide solution, the dehydration operation was continued for 30 minutes to carry out the reaction. Subsequently, excess epichlorohydrin was distilled off from the product under reduced pressure to obtain a crude epoxy resin.
This crude epoxy resin was dissolved in 300 g of methyl isobutyl ketone, 100 g of a 20 wt% aqueous sodium hydroxide solution was added, and the ring was reclosed at a temperature of 85 ° C. for 1 hour. After completion of the reaction, 200 g of water was added and stirred at 80 ° C. for 10 minutes, followed by stationary separation to remove only the aqueous layer. Subsequently, it was washed in the same manner with 200 g of a 1% aqueous sodium phosphate solution to remove only the aqueous layer. Further, 200 g of distilled water having an electric conductivity of 0.31 mS / m was added and stirred at 80 ° C. for 10 minutes, and then allowed to stand for 20 minutes. As a result, it separated into an organic layer, an aqueous layer, and a layer of gel-like impurities floating in the middle. . The pH of the aqueous layer was 7. The aqueous layer and the gel-like impurity layer were left at the bottom of the container, and only the organic layer was taken out and filtered through a filter paper having an opening of about 5 microns to completely remove the insoluble matter. The time required for the filtration operation was 8 minutes. Separately, the gel impurity layer was separated from the aqueous layer, dried and weighed to find 1.9 g. The weight after drying of the gel-like impurities removed by filtration was 0.2 g. In the organic layer, methyl isobutyl ketone was completely removed under reduced pressure while heating to obtain 166 g of the desired purified epoxy resin.
This epoxy resin was a pale yellow crystalline solid having an epoxy equivalent of 184 g / eq. And an amount of saponifiable chlorine of 70 ppm.

<Comparative Example 1>
An epoxy resin production operation was carried out in the same manner as in Example 1, but no washing with a 1% aqueous sodium phosphate solution was performed, and no gel impurities were removed. In the operation of filtering the organic layer containing gel impurities, clogging was severe from the beginning of filtration and the filtration rate was slow. Since about 1/3 of the total amount was filtered, the filter paper was completely replaced. A total of three filter papers were used, and the entire amount was filtered. Meanwhile, it was observed that a part of the epoxy resin crystallized and remained on the filter paper. The time required for the filtration operation was 46 minutes. The weight of the gel-like impurities removed by filtration and the crystallized epoxy resin after drying was 6.2 g. The yield of the obtained resin was 161 g, and the quality was the same as in Example 1.

<Example 2>
Into a 2 L three-necked flask equipped with a thermometer, a stirrer, and a condenser tube, 36.3 g of paraaminophenol, 555 g of epichlorohydrin and 200 g of 2-propanol were charged, dissolved, and reacted at 65 ° C. for 1 hour. Thereafter, 91 g of a 48.5% by weight aqueous sodium hydroxide solution was added dropwise over 1 hour while maintaining the temperature at 65 ° C. Even after completion of the dropwise addition of the aqueous sodium hydroxide solution, the reaction was carried out at 65 ° C. for 30 minutes. Next, 270 g of water was added and stirred at 65 ° C. for 10 minutes, and then allowed to stand. After standing for 15 minutes, it separated into an organic layer, an aqueous layer, and a layer of gel-like impurities floating in the middle. The aqueous layer and the gel-like impurity layer were extracted from the bottom of the container. The weight of the gel impurity after drying was 0.3 g. Excess epichlorohydrin and 2-propanol were distilled off from the organic layer under reduced pressure to obtain a crude epoxy resin.
This crude epoxy resin was dissolved in 200 g of methyl isobutyl ketone, 100 g of a 10% by weight aqueous sodium hydroxide solution was added, and the mixture was reacted at a temperature of 85 ° C. for 1 hour. After completion of the reaction, 100 g of water was added and stirred at 80 ° C. for 10 minutes, and then allowed to stand and remove only the aqueous layer. Furthermore, after adding 200 g of distilled water having an electric conductivity of 0.31 mS / m and stirring at 80 ° C. for 10 minutes, the mixture was allowed to stand for 20 minutes and separated into an organic layer, an aqueous layer and a gel-like impurity layer suspended in the middle. did. The pH of the aqueous layer was 9. The aqueous layer and the gel-like impurity layer were extracted from the bottom of the container. The weight of the gel impurity after drying was 2.2 g. The organic layer was further washed twice with 200 g of water and then filtered with a filter paper having an opening of about 5 microns to completely remove insoluble matters. The time required for the filtration operation was 7 minutes. The weight after drying of the gel-like impurities removed by filtration was 0.1 g. Next, methyl isobutyl ketone was completely removed under reduced pressure while heating to obtain 82 g of the desired purified epoxy resin.
This epoxy resin was a transparent light yellow liquid having an epoxy equivalent of 111 g / eq. And an amount of saponifiable chlorine of 280 ppm.

<Comparative Example 2>
Although the epoxy resin production operation was performed in the same manner as in Example 2, the gel-like impurities were not removed after the glycidylation reaction and after the recyclization reaction. In the filtering operation of the organic layer, a 200-mesh wire mesh (aperture of about 70 microns) was used instead of the filter paper, but the clogging was severe and the filtration rate was slow from the beginning of the filtration. Since about half of the total amount was filtered, the wire mesh was replaced. A total of two wire meshes were used to finish filtering the whole amount. The time required for the filtration operation was 28 minutes. The weight after drying of the gel-like impurities removed by filtration was 3.4 g. The yield of the obtained resin was 78 g, and the quality was almost the same as in Example 2, but turbidity was observed.

  According to the present invention, impurities are removed from the epoxy resin, and a high-purity epoxy resin is obtained. Therefore, the epoxy resin is particularly effectively used as an epoxy resin used for semiconductor encapsulation.

Claims (7)

  A method for producing a purified epoxy resin with few gel impurities, the gel obtained by reacting a compound having an average of 2 or more active hydrogens per molecule with an epihalohydrin in the presence of an alkali metal hydroxide Crude epoxy resin containing a liquid-like impurity is mixed with water in a molten or solution state, then separated into an organic layer and an aqueous layer, and then the gel-like impurities floating between the organic layer and the aqueous layer are removed. A method for producing a purified epoxy resin.   A step of dissolving a crude epoxy resin containing an organic halogen impurity in an organic solvent other than epihalohydrin which dissolves the epoxy resin but is incompatible with water, and subsequently adds an alkali metal hydroxide to the solution as a solid or a solution The step of performing a low chlorination reaction, then the step of separating the organic layer and the aqueous layer in the presence of water, and the step of removing the gel-like impurities floating between the organic layer and the aqueous layer are sequentially performed. A method for producing the described purified epoxy resin.   3. The compound having an average of 2 or more active hydrogens per molecule is at least one compound selected from polyhydric phenol compounds, amino compounds and aminophenols. A method for producing a purified epoxy resin described in 1.   The purified epoxy according to any one of claims 1 to 3, wherein the compound having an average of 2 or more active hydrogens per molecule is a compound containing at least one biphenol. Manufacturing method of resin.   The method for producing a purified epoxy resin according to any one of claims 1 to 4, wherein the saponifiable chlorine content in the obtained epoxy resin is 500 ppm or less.   The method for producing a purified epoxy resin according to any one of claims 1 to 5, wherein the pH of the aqueous layer is 5 or more.   The method for producing a purified epoxy resin according to any one of claims 1 to 6, wherein a temperature at which the operation for removing the gel-like impurities is performed is 20 ° C to 150 ° C.