JPS6337444B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrical insulating material made of a novel cured epoxy resin having low viscosity and excellent cured properties. Various types of epoxy resins are industrially manufactured and commercially available, and among them, diglydyl ether (hereinafter referred to as bisphenol A) of 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as bisphenol A)
Abbreviated as type epoxy resin. ) is a general-purpose epoxy resin, and in particular, liquid bis-A type epoxy resin has fluidity at room temperature, which is advantageous in terms of workability. acids,
Mechanical strength, heat resistance, adhesiveness, electrical insulation properties of cured products cured using curing agents such as acid anhydrides,
It is well known that it is used in various applications such as paint adhesives, electrical insulation materials, FRP matrices, flooring materials, etc. due to its excellent properties such as water resistance. However, this useful liquid bis-A type epoxy resin still has a disadvantage of high viscosity.
That is, this liquid bis-A type epoxy resin is usually produced by reacting bisphenol A with excess epichlorohydrin, and it is known that as the amount of epichlorohydrin used increases, the molecular weight and viscosity decrease. However, the reduction in resin viscosity by increasing the amount of epichlorohydrin used has a limit of about 7000 CPS (25°C).
Liquid A-type epoxy resin with a relatively low viscosity of 7,000 to 10,000 CPS easily crystallizes, especially in winter, when it solidifies and loses its original fluidity at room temperature and loses its value as a product.
The liquid type epoxy resin that is usually manufactured and sold industrially has an epoxy equivalent of about 190 and is heated at 25°C.
It has a high viscosity of about 9,000 to 15,000 CPS. Therefore, such liquid screw A
For the purpose of lowering the viscosity of type epoxy, low-viscosity reactive diluents such as butyl glycidyl ether and phenyl glycidyl ether, or non-reactive diluents such as phthalate esters and alkyl phenols, are used in combination. The use of these diluents inevitably reduces the mechanical strength of the cured product,
This is accompanied by a decrease in the physical properties of the original cured bis-A type epoxy resin, such as a decrease in heat resistance and adhesiveness. Furthermore, depending on the type of diluent, it is highly toxic and poses health problems for workers. Although the general-purpose liquid bis-A type epoxy resin has excellent properties as a cured product, it cannot be used satisfactorily due to its inherent high viscosity. Diglycidyl ether of bis(4-hydroxyphenyl)methane (commonly known as bisphenol F) (hereinafter referred to as bis-F epoxy resin) is a low-viscosity epoxy resin that retains a considerable portion of the properties of the cured product of liquid bis-A epoxy resin. ) is known (JCIA Monthly Report, (10), 29 (1975)). This screw F
Type epoxy resin has an epoxy equivalent of approximately 180 at 25
It has a low viscosity of about 3000 CPS at ℃, and its cured product is quite similar to liquid bis A type epoxy resin, but it has a serious drawback of low heat resistance. That is, according to the above-mentioned JCIA Monthly Report, when triethylenetetraamine is used as a curing agent, the heat distortion temperature of a cured product of bisF type epoxy resin is 104 ° C.
Heat distortion temperature of cured product of Bis A type epoxy resin 121
considerably lower than ℃. Although the bis-F type epoxy resin has the advantage of having a low viscosity, its application to applications requiring heat resistance equivalent to that of the bis-A type epoxy resin is naturally limited. In view of the above-mentioned circumstances, the inventors of the present invention made extensive studies to obtain an epoxy resin that takes advantage of the high heat distortion temperature and other advantages of a liquid bis-A type epoxy resin cured product and has a low viscosity. formula is real is represented by formula (I), where A is the epoxy equivalent and B is the hydrolyzable chlorine equivalent, A×B/(A
A divalent residue obtained by removing the hydrogen atom of the hydroxyl group from 1,1-bis(hydroxyphenyl)ethane in which the value expressed by +B) is about 170 to about 190, and X is represented by the formula () We discovered the surprising fact that this epoxy resin exhibits a low viscosity equivalent to that of Bis-F type epoxy resin, and that the heat resistance and other properties of the cured product are equal to or better than those of Bis-A type epoxy resin. We have arrived at an invention that completely satisfies the needs that have existed for a long time. It is known that an epoxy resin can be produced by reacting a dihydric phenol represented by the above formula () with epichlorohydrin or dichlorohydrin in the presence of an alkali. For example, Plaste und
Kautschuck, 8 , (4), 171-174 (1961), J.
Angew.chem., Bd32, 1124-1129 (1959),
Khim, Prom., 468-469 (1961), Tokuko Sho 26-
Publication No. 4638, etc. describes the properties and curing of epoxy resin produced by reacting 1,1-bis(4-hydroxyphenyl)ethane with epichlorohydrin or dichlorohydrin in the presence of an aqueous sodium hydroxide solution. It describes the properties of things. However, these known documents only describe synthesis examples of epoxy resins using a small amount of 3 moles or less of epichlorohydrin or dichlorohydrin per 1 mole of 1,1-bis(4-hydroxyphenyl)ethane; According to the description in the literature, the value expressed by A×B/(A+B) is 200 or more, and the inventor's additional tests revealed that it was also 200 or more. Furthermore, the known literature does not contain any detailed description regarding the viscosity of the synthesized epoxy resin, and there is no description at all regarding the heat resistance of the cured product of the epoxy resin. Furthermore, according to the inventor's additional tests, the epoxy resin produced by these methods is 25
It is a solid solution with almost no fluidity at 25°C, and under the same conditions, bisphenol A epoxy resin also melts at 25°C.
Both were in a solid solution state, and there was almost no difference in viscosity at 25°C. However, the present inventor has discovered that A If the value expressed by ×B/(A+B) is within the range mentioned above, it has a low viscosity equivalent to that of Bis-F type liquid epoxy resin, and its cured product has physical properties equivalent to or better than Bis-A type liquid epoxy resin. They obtained the important knowledge that That is, the present invention has a structure substantially represented by the above general formula (I), and where A is the epoxy equivalent and B is the hydrolyzable halogen equivalent, A×
The value displayed as B/(A+B) is about 170 or about
The present invention relates to providing an electrical insulating material made of a cured product of liquid epoxy resin No. 190. In addition, in formula (I), X is a divalent residue obtained by removing the hydrogen atom of the hydroxyl group from 1,1-bis(hydroxyphenyl)ethane represented by the above formula (), and n
is the number of repeating units. The viscosity of the epoxy resin used in the present invention is at 25℃.
It has an extremely low viscosity of 2,500 to 7,000 CPS, and its cured product exhibits heat resistance, that is, heat distortion temperature, equivalent to that of conventional liquid bis A-type epoxy resins. In this respect, it is far superior to bis-F type epoxy resin. Of course, other properties are also equal to or better than those of the bis A type epoxy resin. In addition, the epoxy resin used in the present invention has a sufficiently low viscosity even without the use of a diluent, so it may not be necessary to use a diluent, and even if it is used to further lower the viscosity, it will not have the same viscosity. Since the amount used for this purpose is much smaller than that of bis-A epoxy resins, health problems for workers are significantly reduced, and it is also possible to obtain the desired results from formulations whose viscosity has been lowered by diluents. The mechanical strength and heat resistance of the resulting cured product are superior to those of the bis A type epoxy resin. Other objects and advantages of the present invention will be better understood from the following detailed description of the present invention. The structural formula of the epoxy resin used in the present invention is substantially represented by the above formula (I). Formula (I)
In the formula (),
-hydroxyphenyl)ethane, 1,1-bis(2-hydroxyphenyl)ethane, 1,1-bis(3-hydroxyphenyl)ethane, 1-(2-hydroxyphenyl)ethane,
-hydroxyphenyl)-1-(4-hydroxyphenyl)ethane, 1-(3-hydroxyphenyl)
-1-(4-hydroxyphenyl)ethane, 1-
Examples include (2-hydroxyphenyl)-1-(3-hydroxyphenyl)ethane, and 1,1
-bis(4-hydroxyphenyl)ethane, 1,
1-bis(2-hydroxyphenyl)ethane, 1
Preferred examples include -(2-hydroxyphenyl)-1-(4-hydroxyphenyl)ethane, and particularly preferred is 1,1-bis(4-hydroxyphenyl)ethane. One of the important structural requirements for exerting the advantages of the epoxy resin used in the present invention is that X is a residue of a divalent phenol represented by the formula (), and X is a residue of a bisphenol A or The effects of the present invention cannot be achieved with bisphenol F residues. The epoxy resin used in the present invention is A when the epoxy equivalent is A and the hydrolyzable halogen equivalent is B.
The value expressed as xB/(A+B) is about 170 to about 190, preferably about 171 to about 185, more preferably about 171 to about 182. Here, epoxy equivalent means the weight (unit: g) of epoxy resin per 1 gram equivalent of epoxy group, and a detailed explanation and measurement method can be found in Hiroshi Kakiuchi, ed., Epoxy Resin (Publisher, Shokodo), 161 or It is described on page 170, and the following measurement method is exemplified. 1. Accurately weigh 0.2 to 0.4 g of epoxy resin in a 200 ml Erlenmeyer flask, add 25 ml of dioxane, and dissolve. 2 25ml of 1/5 normal hydrochloric acid solution (dioxane solution)
Add the ingredients accurately, seal the bottle tightly, mix thoroughly, and let stand for 30 minutes. 3. After adding 50 ml of toluene-ethanol (1:1, volume ratio) mixed solution, titrate with 1/10 N sodium hydroxide solution using a cresol lead as an indicator. Calculate the epoxy equivalent weight according to the following formula: A=W×1000/(Q-S)×0.1×f W: Weight of sample (g) S: Titration amount of 1/10 normal sodium hydroxide solution (ml) f: Titration amount of 1/10 normal sodium hydroxide solution Potency Q: Titration amount of 1/10N sodium hydroxide solution in blank test (ml) Hydrolyzable halogen equivalent is the weight per gram equivalent of hydrolyzable halogen (unit: g)
means. Hydrolyzable halogen is, for example, an epoxy resin produced according to the following formula () and formula () when producing the epoxy resin used in the present invention by reacting epichlorohydrin with a dihydric phenol represented by the formula (). but, It mainly consists of halogen that remains in the form of () after the reaction of formula () is not completed.
It is not always good for the hydrolyzable halogen to be completely absent, but the amount should be adjusted depending on the application. The following method is exemplified as a method for measuring the hydrolyzable halogen equivalent. 1. Accurately weigh about 5 g of epoxy resin into a 300 ml round bottom flask, add toluene-methanol mixed solvent (1:
1. Add 100ml (volume ratio) and dissolve. 2 Methanolic 1/10 normal potassium hydroxide solution 50
ml and then heated under reflux for 30 minutes in an oil bath at 130°C. 3 Then, allow to cool and titrate with 1/10N aqueous hydrochloric acid solution using phenolphthalein as an indicator. Calculate the hydrolyzable halogen equivalent according to the following formula: B=W×1000/(Q-S)×0.1×f W: Weight of sample (g) S: Titration amount of 1/10 N hydrochloric acid aqueous solution (ml) f: Titer of 1/10 N hydrochloric acid aqueous solution Q: Titration amount (ml) of 1/10N hydrochloric acid aqueous solution in a blank test When the value expressed as A×B/(A+B) exceeds approximately 190 using the above epoxy equivalent A and hydrolyzable halogen equivalent B as variables. If the viscosity of the epoxy resin is high or less than about 170, the epihalohydrin may be used in industrial practice when adopting a suitable method for producing the epoxy resin by reacting the dihydric phenol represented by the above formula () with epihalohydrin. It is excluded from the present invention because it must be used in an unbearably large amount. In the present invention, "having substantially the structure of the formula (I)" means that a small amount of the hydrolyzable halogen represented by the formula () remains due to the method adopted when producing the epoxy resin used in the present invention. Alternatively, the epoxy resin may be left intentionally, and such epoxy resins are also included in the epoxy resin used in the present invention. Epoxy equivalent A and hydrolyzable halogen equivalent B
is appropriately selected depending on the use of the epoxy resin used in the present invention, but the epoxy equivalent A is preferably about 170 to about 190, particularly preferably about 171 to about 185. Further, it is preferable that the hydrolyzable halogen equivalent B is 3,500 or more, particularly about 10,000 or more. The viscosity of the epoxy resin used in the present invention is approximately
2500 to about 7000 CPS, but about 2500 to about
The effect of the present invention is remarkable with 5000 CPS, which is extremely preferable. The epoxy resin used in the present invention can be produced by reacting 1 mole of the dihydric phenol represented by the above formula () with epihalohydrin and/or dihalohydrin. Examples of epihalohydrin include epichlorohydrin and epibromohydrin.
or 1,3-dichloro-2 as dihalohydrin
-propanol, 2,3-dichloro-1-propanol, 1,3-dibromo-2-propanol and 2,3-dibromo-1-propanol. These epihalohydrins and dihalohydrins may be used in combination. Among these, the use of epihalohydrin is preferred, and the use of epichlorohydrin is most preferred. The amount of epihalohydrin and/or dihalohydrin used is usually about 4.5 mol or more, preferably about 5 to about 40 mol, more preferably about 5.5 to about 30 mol, per 1 mol of the dihydric phenol. Various methods can be used to react the divalent phenol of formula () with epihalohydrin and/or dihalohydrin. One of them is a method of directly reacting the divalent phenol with epihalohydrin and/or dihalohydrin in the presence of an alkaline substance. This method is a method in which the etherification step of formula () and the dehydrohalogenation step of formula () are performed simultaneously. At this time, the alkali compound is usually about 1 times or more moles relative to the dihydric phenol, preferably about 1.8 to 2 times the mole.
It is carried out in the presence of water at a temperature of about 60 to about 90°C, using about twice the molar amount. As the alkali compound, it is preferable to use an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, lithium hydroxide, etc., and the use of sodium hydroxide is recommended industrially. After the reaction is completed, unreacted epihalohydrin and/or dihalomodrine, water, generated salts, etc. are removed from the reaction product, and the epoxy resin used in the present invention is obtained by drying.
When this method is adopted, the epoxy equivalent A and the hydrolyzable halogen equivalent can be adjusted by adjusting the amount of the alkali compound used. However, it is possible to adopt a method in which the dihydric phenol and epihalohydrin are reacted in the presence of an etherification catalyst to perform the etherification step of the formula (), and then the dehydrohalogenation step of the formula () is performed using an alkaline compound. Highly preferred. Suitable catalysts used in the etherification process include tertiary amines such as trimethylamine, triethylamine; tertiary phosphines such as triphenylphosphine, tributylphosphine; tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride; ,
Quaternary ammonium compounds such as tetraethylammonium bromide and choline chloride; other tetramethylphosphonium, bromide or iodide, triphenylpropylphosnium, bromide, benzyldibutylsulfonium chloride, benzyldimethylsulfonium chloride The use of quaternary ammonium compounds is particularly recommended. The amount of these etherification catalysts used in the etherification step is about 0.25 to about 5 mol%, preferably about 0.5 to about 3 mol%, based on the dihydric phenol. In the etherification step, the reaction is carried out until at least about 50%, preferably 80% or more of the hydroxyl groups of the dihydric phenol are etherified. Also usually about
The reaction is carried out at a temperature of 70 to about 110°C for about 1 to about 12 hours. It is preferable that water is substantially absent, and it is recommended that the amount of water be 3.0% by weight or less based on the total amount of the reaction system. The reaction product from the etherification step is supplied to the next dehydrohalogenation step as it is, that is, containing unreacted epihalohydrin. An alkali compound is used as the dehydrohalogenating agent, and the same alkali compound as used in the first method described above can be used, and industrially it is preferable to use sodium hydroxide. . The value of the hydrolyzable halogen equivalent B of the epoxy resin used in the present invention can be arbitrarily adjusted by adjusting the amount of the alkali compound used. Usually, the amount of alkaline compound used is at least 1 mole based on the dihydric phenol used in the etherification step, preferably
Use 1.6 times the mole or more. However, in order to avoid problems such as gelation, it is preferable to set the amount to 2 times the mole or less. The dehydrohalogenation step is typically carried out at a temperature of about 60 to about 100°C for about 1 to about 3 hours.
Depending on the type of alkali compound, for example, when sodium hydroxide is used, water may be produced as a by-product, and it is recommended to remove this water from the reaction system. After completion of this dehydrohalogenation step, the epoxy resin used in the present invention is obtained by removing unreacted epihalohydrin, removing the generated salt, and drying.
Epihalohydrin is removed by distillation under reduced pressure, and salts are removed by washing with water or the like. If necessary, a neutralization step using a weak acid such as phosphoric acid or sodium dihydrogen phosphate is added at an intermediate stage. When it is desired to further reduce the hydrolyzable halogen content of the obtained epoxy resin, especially when the value of the hydrolyzable halogen equivalent B is desired to be approximately 10,000 or more, the second dehalogenation using the alkali compound described above is performed. This can be achieved by hydrogenation. This step can be carried out simultaneously with the desalting or as an intermediate step thereafter. The electrical insulating material of the present invention is a cured product obtained by adding a curing agent to the above epoxy resin and blending various auxiliary materials as necessary, and is suitable for various electrical insulating materials such as electrical insulating laminates. used for purposes. As the curing agent, known curing agents used for curing bis A type epoxy resins, such as polyamines, modified polyamines, polyamide polyamines, modified polyamide polyamines, polyhydric carboxylic acids, acid anhydrides, etc. Any of boron trifluoride-amine complexes, imidazoles, dicyanidiamides, etc. can be used, and the selection of these curing agents is appropriately selected according to the application, similar to the bis A type liquid epoxy resin. Moreover, the amount to be used can also be determined from the same viewpoint as for the bis A type liquid epoxy resin. For example, when poneamines are used as a curing agent, the amount to be used can be determined by the ratio of the epoxy equivalent of the epoxy resin used in the present invention to the active hydrogen equivalent of the polyamine. A curing accelerator may also be used if necessary. Diluents are used to reduce the viscosity of epoxy resins or filler-containing mixtures, and include non-reactive diluents such as phthalates, ethers or esters of glycols, phenols, long-chain alkylene oxides; butyl Examples of reactive diluents include glycidyl ethers such as glycidyl ether, phenyl glycidyl ether, p-butylphenyl glycidyl ether, and cresyl glycidyl ether. The use of these diluents usually reduces the strength of the cured epoxy resin product, and reactive diluents are harmful to the human body, so it is preferable not to include them or to use them in small amounts. However, the epoxy resin used in the present invention Since the viscosity is low, there are cases where it is not necessary to blend it, and even when it is necessary to blend it, only a small amount is required, and therefore the cured product can maintain sufficient strength. Examples of fillers that can be used include calcium carbonate, clay, asbestos, silica, mica, quartz powder, cement, aluminum powder, graphite, titanium oxide, alumina, iron oxide, glass powder, and the like. The type of filler is appropriately selected as in the case of the bis-A liquid epoxy resin. In addition, fillers such as calcium carbonate and clay can be used with epoxy resin,
Since it is extremely cheap compared to hardening agents, etc., a method of adding a large amount to Bis A type liquid epoxy resin is adopted in order to obtain an inexpensive cured product.However, due to the decrease in workability due to the increase in viscosity, I've reached my limit. However, since the epoxy resin used in the present invention has a low viscosity, it is possible to incorporate more of the above-mentioned filler, and therefore it is possible to provide a cured product at a lower cost. For the purpose of coloring, coloring agents such as titanium oxide, antimony oxide, toluidine red, Hansa yellow, iron oxide powder, phthalocyanine blue, phthalocyanine green, and carbon black can also be blended. Furthermore, a fiber-reinforced resin can also be obtained by impregnating glass fiber, glass cloth, carbon fiber, carbon cloth, etc. with the epoxy resin and curing agent of the present invention in the same manner as the bis A type liquid epoxy resin. Furthermore, the epoxy resin used in the present invention can be used in combination with a bis-A type liquid epoxy resin or a bis-F type epoxy resin, and even if the epoxy resin used in the present invention is used in combination with a bis-A type liquid epoxy resin or a bis-F type epoxy resin, The structure differs depending on the type of phenol, but phenols with different structures may be used in combination. The present invention will be specifically described below with reference to Examples. Comparative Example 1 277.5 g of epichlorohydrin (sometimes abbreviated as ECH) and 1,1-bis(4-hydroxyphenyl)ethane (sometimes abbreviated as bisAD)
160.5g (molar ratio of ECH and BisAD (ECH/BisAD)
For AD), 4) and 0.63 g of choline chloride, which corresponds to 0.6 mol% based on bis-AD, were charged into a four-necked glass flask equipped with a stirrer and reflux device in step 1, and reacted at 90°C for 4 hours with stirring. I went there. 58.8g of solid sodium hydroxide while continuing to maintain the temperature at 90℃
(corresponding to 1.96 mol per mol of BisAD) was added continuously over 90 minutes. At this time, the pressure was reduced to 600 mmHg to remove the generated water from the system, and the azeotropic epichlorohydrin was returned to the system. After the addition of sodium hydroxide was completed, water was removed from the system, and after no more water was produced, unreacted ECH was distilled out of the system, and almost no ECH was observed to be distilled out. After getting used to it, put it under a reduced pressure of 5mmHg.
It was heated to 120°C to completely remove epichlorohydrin. Add 300g of xylene and 320g of water to the resulting reaction product.
was added and stirred, the generated common salt was transferred to the aqueous phase, and after standing still, the aqueous phase was removed. Then a 4% by weight sodium hydroxide solution was added to the oil phase.
75 g was added and stirred at 70°C for 1 hour to perform the second dehydrochlorination. After oil and water separation, 3% by weight in the oil phase
Neutralization was performed by adding 10 ml of an aqueous solution of sodium dihydrogen phosphate, water was subsequently removed by azeotropic distillation, and the oil phase was filtered through a 4G glass filter to remove salts. The desired epoxy resin was obtained by completely removing xylene from the salt-free oil phase under reduced pressure (150° C./2 mmHg). Table 1 shows the properties of the obtained epoxy resin. The viscosity was measured using a B-type viscometer (manufactured by Tokyo Keiki). Next, the epoxy resin used above was cured using EPOMIKQ-643 (Mitsui Petrochemical Epoxy Co., Ltd., modified polyamine; active hydrogen equivalent: 55) as a curing agent. The bending strength and compressive strength were measured according to JIS K6911. The heat distortion temperature was then measured according to ASTM D648. The results are shown in Table 1. The blending ratio of the curing agent and the epoxy resin was the same as the ratio of the active hydrogen equivalent of the curing agent to the epoxy equivalent of the epoxy resin. Also, curing is done after heating at 100℃ for 2 hours.
This was further carried out by heating at 150°C for 4 hours. Examples 1, 2, 3, 4 In Comparative Example 1, epichlorohydrin and biz
Other than changing the amount of epichlorohydrin used so that the molar ratio with AD (ECH/bisAD) is 6 (Example 1), 10 (Example 2), 12 (Example 3), 22 (Example 4) The same operation as in Comparative Example 1 was performed. The results are shown in Table 1. Comparative Example 2 In Example 3, screw (4-
The same procedure was carried out except that 159 g of hydroxyphenyl)methane (ECH/bisphenol (mole ratio) corresponds to 12) was used. The results are shown in Table 1. Comparative Example 3 In Comparative Example 1, 169.5 g of 2,2-bis(4-hydroxyphenyl)propane was used instead of BisAD.
(ECH/bisphenol (molar ratio) corresponds to 12)
The same operations were performed except for the use of The results are shown in Table 1. Comparative Example 4 Commercially available bis A type epoxy resin EPOMIKR-140 (Mitsui Petrochemical Epoxy Co., Ltd.)
A cured product was obtained using the same procedure as in Comparative Example 1, and its physical properties were measured. The results are shown in Table 1. Comparative Example 5 100 parts by weight of the epoxy resin of Comparative Example 4 and 5 parts by weight of butyl glycidyl ether as a reaction diluent were mixed to prepare an epoxy resin formulation with a viscosity of approximately 3000 CPS (25°C), which was the same as that of Comparative Example 1. A cured product was obtained by this operation, and its physical properties were measured. The results are shown in Table 1. The description of the properties of the epoxy resin in Table 1 of this comparative example is for a mixture of EPOMIKR-140 and butyl glycidyl ether.

【table】

[Table] From the results in Table 1 above, the epoxy resin of the present invention has a lower viscosity than the bis A type epoxy resin, and the heat distortion temperature and other physical properties of the cured product are equivalent to the bis A type epoxy resin. Screw F type, screw A
It is clear that it is superior to type epoxy resin.
Furthermore, Comparative Example 5 shows that when the viscosity of the bis A type epoxy resin is simply lowered with a reactive diluent, it is inferior to the cured product of the epoxy resin of the present invention. Comparative example 6 Publicly known literature J.Angew.Chem., Bd32, 1124-1129
(1959), the molar ratio of epichlorohydrin to bisAD (ECH/bisAD) was 3.0.
The epoxy resin was manufactured at the time. That is, after dissolving 1 mol part of BisAD in 3 mol parts of epichlorohydrin, a 15% by weight aqueous sodium hydroxide solution equivalent to the epichlorohydrin was added while maintaining the flask temperature at 25°C. The flask contents were then heated at 25°C for approximately 10
Stir for minutes, then increase the temperature to 52-55 °C and
The mixture was stirred for a minute, then heated to 85°C, and stirred at that temperature for 90 minutes. Afterwards, the contents of the flask were washed with warm water until neutral, and then ethyl acetate (50%) - toluene (25%) - acetone (25%) was washed with warm water until neutral.
%) of a mixed solvent, water was removed by azeotropic dehydration, and the solution was filtered to remove the solvent, yielding a solid solution resin. The epoxy equivalent weight A of this epoxy resin was 268, the amount of hydrolyzable chlorine was 0.01% by weight, the hydrolyzable halogen equivalent weight B was 350,000, and A×B/(A+B) was 268. In addition, the viscosity could be measured in a solid solution state. As described above, the epoxy resins disclosed in conventional known documents are completely different from the epoxy resin of the present invention. Example 5, Comparative Examples 7 and 8 The formulations shown in Table 2 were cured under conditions: 100°C x 2 hours;
The electrical and mechanical properties of the cured product cured at 150°C for 4 hours are shown.

【table】

【table】

Claims (1)

[Claims] 1 Having a structure substantially represented by general formula (I), and where A is the epoxy equivalent and B is the hydrolyzable halogen equivalent, expressed as A×B/(A+B) An electrical insulating material made of a cured liquid epoxy resin with a value of 170 to 190. [In formula (I), X is a divalent residue obtained by removing a hydrogen atom from the hydroxyl group of 1,1-bis(hydroxyphenyl)ethane, and n is the number of repeating units. ]