JP2566178C - - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an epoxy resin powder composition that can provide a cured product having excellent physical properties such as heat resistance and is less likely to cause blocking. (Prior Art) Curable epoxy resin compositions have been widely used as non-polluting, resource-saving, energy-saving molding materials, paints, insulating materials, impregnated fixing materials, and the like. One of the epoxy resins used for these purposes is a crystalline epoxy resin. Crystalline epoxy resins have a significantly lower melt viscosity than commonly used amorphous solid epoxy resins, such as bisphenol A type epoxy resins and novolak type epoxy resins. Used in fields where sex is required. In particular, an epoxy resin obtained by the reaction of 4,4'-bishydroxy-3,3 ', 5,5'-tetrabiphenyl with epihalohydrin (hereinafter referred to as "tetramethylbiphenyl type epoxy resin") Is widely used because it has an excellent melting point (melting point of 80 to 110 ° C.) and excellent properties such as giving a cured product having relatively excellent heat resistance. However, ordinary tetramethylbiphenyl type epoxy resins have the structural formula And a large amount of impurities. The main impurities are phenolic hydroxyl group-containing compounds as raw materials that remain in the resin in an unreacted state during production, polymer compounds such as dimers and trimers that are by-products of the production reaction, and halogen-containing compounds. Compounds, glycol group-containing compounds and the like. These impurities not only deteriorate the properties such as heat resistance of the cured resin, but also reduce the crystallinity of the epoxy resin itself.When the epoxy resin composition using such an epoxy resin is stored at around room temperature, Had the disadvantage of easily blocking. (Problems of the Invention) An object of the present invention is to provide an epoxy resin powder composition which can provide a cured product having extremely excellent physical properties such as heat resistance and which hardly causes blocking. (Means for Solving the Problems) The present invention has achieved the object by an epoxy resin powder composition using a specific tetramethylbiphenyl type epoxy resin. That is, the epoxy resin powder composition of the present invention comprises, in an epoxy resin powder composition containing at least an epoxy resin and a curing agent,
A crystalline epoxy resin obtained by the reaction of 4,4'-bishydroxy-3,3 ', 5,5'-tetramethylbiphenyl with epihalohydrin, having the formula [Wherein, X is a structural formula in gel permeation chromatographic analysis of the epoxy resin. Wherein Y is the peak area of the compound (A) in the same analysis, and Y is the peak area of the compound (A). Is the area of all peaks other than the peak of the compound (A) and the peak of the compound (B) detected between the peak of the compound (B) and the peak of the compound (B). These X and Y were used as columns having an exclusion limit molecular weight of 20,000, a theoretical plate number of 16,000 and a length of 30 c
m column, the excluded ocular molecular weight is 60,000, and the number of theoretical plates is 16,000.
The values are measured using a column in which a 0 cm column is connected in series, using tetrahydrofuran as a moving bed at a flow rate of 1 ml / min, and using a 254 nm ultraviolet detector. The peak area ratio (R) of the gel permeation chromatograph analysis is 0.05 or less, and the melting onset temperature measured at a rate of 5 ° C./min using a microscope is 88 ° C. or more and 99 ° C. A composition using the following epoxy resin. The epoxy resin used in the epoxy resin powder composition of the present invention comprises 4,4'-bishydroxy-3,3 ', 5,5'-tetramethylbiphenyl and epihalohydrin such as epichlorohydrin and epibromohydrin. , In the presence of an alkali such as sodium hydroxide or potassium hydroxide. The main reaction of this production reaction is an addition reaction of epihalohydrin to 4,4'-bishydroxy-3,3 ', 5,5'-tetramethylbiphenyl, and a 4,4'-bishydroxy-3,4 This is a reaction for producing 3 ', 5,5'-tetramethylbiphenyldiglycidyl ether [compound represented by the aforementioned structural formula (A)]. As described above, the above-mentioned structural formula is produced by various side reactions. (B) polymer compounds such as dimers and trimers, halogen-containing compounds, glycol-containing compounds, etc., which are contained in the resulting epoxy resin as impurities, '-Bishydroxy-3,3', 5
A part of 5'-tetramethylbiphenyl remains unreacted and is contained in the produced epoxy resin. These impurities increase the peak area ratio (R) in the gel permeation chromatography of the epoxy resin and lower the melting start temperature, and furthermore, the peak area ratio (R ), The epoxy resin having a low melting start temperature remarkably deteriorates the cured resin properties such as heat resistance, reduces the crystallinity of the resin itself, and facilitates the blocking of the powder composition. Become. For these reasons, in the present invention, 4,4 'is used as the epoxy resin.
A crystalline epoxy resin obtained by the reaction of -bishydroxy-3,3 ', 5,5'-tetramethylbiphenyl with epihalohydrin, wherein the peak area ratio (
R) is 0.05 or less, preferably 0.04 or less, and the melting start temperature is 88 ° C or more and 99 ° C or less , preferably 90 ° C or more and 99 ° C or less . The epoxy resin powder composition of the present invention using such a specific crystalline epoxy resin gives a cured product having excellent physical properties such as heat resistance, and has a high melt viscosity due to the high crystallinity of the epoxy resin itself. It is low and hardly causes blocking when stored at around normal temperature. FIG. 1 shows an example of the results of the gel permeation chromatography analysis of the crystalline epoxy resin used in the present invention. The peak A is the peak of the compound represented by the structural formula (A). And peak B is a peak of the compound represented by the structural formula (B). Then, the peak B is detected about 19 to 20 minutes after the injection, and the peak A is also detected at about 21 to 22 minutes.
Minutes later, peak C is also usually detected between peak B and peak A. The crystalline epoxy resin having a peak area ratio (R) of 0.05 or less and a melting start temperature of 88 ° C. or more and 99 ° C. or less used in the present invention is the above-described 4,4′-crystalline epoxy resin. Reaction conditions for the presence of alkali of bishydroxy-3,3 ', 5,5'-tetramethylbiphenyl and epihalohydrin, for example, the molar ratio of tetramethylbiphenyl to epihalohydrin, the molar ratio of tetramethylbiphenyl to alkali metal hydroxide It can be produced by precisely controlling the reaction temperature, reaction time, water concentration during the reaction and the like. In particular, the epihalohydrin used in the reaction slightly varies depending on other reaction conditions, but is preferably used in an amount of 7 mol or more per 1 mol of tetramethylbiphenyl. The amount of the alkali metal hydroxide used is preferably 2 mol or more per 1 mol of tetramethylbiphenyl. Further, the specific crystalline epoxy resin used in the present invention may be produced by applying a purification method such as a method of recrystallization from a solvent to a tetramethylbiphenyl type epoxy resin produced by a usual method. Can be. The epoxy resin powder composition of the present invention may be prepared using only the specific crystalline tetramethylbiphenyl type epoxy resin described above as the epoxy resin, but is prepared by using another epoxy resin solid at room temperature in combination. You can also. Examples of other epoxy resins that can be used in combination include a bisphenol A type solid epoxy resin, a bisphenol F type solid epoxy resin, and a cresol novolak type solid epoxy resin. When the other crystalline epoxy resin is used in combination, the specific crystalline tetramethylbiphenyl type epoxy resin is used in an amount of at least 20% by weight, preferably 35% by weight or more, more preferably 45% by weight based on the total epoxy resin. That is all. If the specific crystalline tetramethylbiphenyl type epoxy resin is used in a small proportion, the intended effect of the present invention cannot be sufficiently exhibited. The epoxy resin powder composition of the present invention may contain a curing agent, and may further contain a curing accelerator, an inorganic filler, a coupling material, a flame retardant, a plasticizer, a pigment, and the like. As the curing agent, a general curing agent for epoxy resin can be used as long as it is solid at normal temperature. Examples of such usable curing agents include acid-terminated polyesters, trimellitic anhydride, acid anhydrides such as pyromellitic anhydride, dicyandiamide, amines such as diaminodiphenylmethane, phenol, and the like.
Novolak-type phenolic resins obtained by a condensation reaction of phenols such as cresol, butylphenol, resorcin, and bisphenol A with aldehydes or ketones such as formaldehyde, benzaldehyde, hydroxybenzaldehyde, glyoxal, acetone and cyclohexanone. . Particularly preferred curing agents are novolak phenolic resins. Examples of the curing accelerator include 2-methylimidazole and 2-ethyl-4
Imidazoles such as -methylimidazole; amines such as 2,4,6-tris (dimethylaminomethyl) phenol and benzyldimethylamine; and organic phosphorus compounds such as tributylphosphine and triphenylphosphine. Examples of the inorganic filler include fused silica, crystalline silica, glass powder, alumina, and zircon. Examples of the flame retardant include brominated epoxy resin, antimony trioxide, and phosphoric acid. Can be (Examples, etc.) Hereinafter, the epoxy resin production examples, examples, and comparative examples will be described in detail. Epoxy Resin Production Examples 1 to 3 In a three-necked flask having an internal volume of 31 equipped with a thermometer, a stirring device, and a cooling tube, 4,4 ′
-Bishydroxy-3,3 ', 5,5'-tetramethylbiphenyl and epichlorohydrin were charged in the respective amounts shown in Table 1, and dissolved by heating to 95 ° C. Next, a 48.5% aqueous sodium hydroxide solution shown in Table 1 was added dropwise over 2 hours. Thereafter, water was removed from the reaction system by azeotropic distillation with epichlorohydrin at a temperature of 95 to 100 ° C. for 30 minutes, and epichlorohydrin was separated from the azeotropic distillate and reacted while returning to the reaction system. After the completion of the reaction, the product was washed with water to remove by-product salts and unreacted sodium hydroxide. Next, the excess epichlorohydrin was removed by evaporation under reduced pressure (5 mmHg) from the reaction mixture to obtain each tetramethylbiphenyl type epoxy resin. Table 1 shows the peak area ratio and the melting start temperature of each of the obtained epoxy resins.
Was as shown in FIG. Epoxy Resin Production Example 4 200 g of the tetramethylbiphenyl type epoxy resin obtained in Production Example 3 and 250 g of toluene were placed in a flask equipped with a reflux condenser, and heated to boiling reflux to dissolve the epoxy resin. After complete melting, the mixture was gradually cooled to room temperature, and then kept at room temperature for 5 hours to precipitate epoxy resin crystals. Next, the crystals were filtered to obtain 130 g of a purified epoxy resin. This purified epoxy resin had a peak area ratio of 0.01 and a melting start temperature of 99 ° C. Examples 1-3 Comparative Examples 1-2 Each tetramethylbiphenyl type epoxy resin obtained in the epoxy resin production examples 1-4, orthocresol novolak type epoxy resin, phenol novolak as a curing agent, triphenylphosphine as a curing accelerator, Silica powder was used as a filler, and dry-mixed using a Henschel mixer at each ratio shown in Table 2 to obtain each epoxy resin powder composition. In this case, the epoxy resin, the curing agent, and the curing accelerator used were those that were crushed, sieved using a 100-mesh sieve, and passed through a sieve. Next, the blocking resistance of each of the obtained powder compositions was examined. Further, the glass transition point after curing each powder composition at 180 ° C. for 8 hours was measured to examine the heat resistance. The results are as shown in Table 2. Each of the powder compositions of Examples 1 to 3 has excellent blocking resistance as compared with the powder compositions of Comparative Examples 1 and 2, and the glass transition temperature of the cured product. And high heat resistance. (Effect of the Invention) The epoxy resin powder composition of the present invention is less likely to cause blocking when kept at room temperature, has excellent storage stability, has a low melt viscosity, has excellent workability, and has heat resistance and the like. Since it gives a cured product having excellent physical properties, it can be advantageously used as various molding materials, paints, insulating materials, impregnated fixing materials, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a drawing showing an example of the results of gel permeation chromatographic analysis of a tetramethylbiphenyl type epoxy resin used in the present invention, wherein peak A is the peak of compound (A) and peak B is Indicates a peak of the compound (B), and peak C indicates a peak of another impurity.

Claims (1)

Claims (1) In an epoxy resin powder composition containing at least an epoxy resin and a curing agent, 4,4'-bishydroxy-3,3 ', 5,5
A crystalline epoxy resin obtained by reacting '-tetramethylbiphenyl with epihalohydrin, comprising a compound of the formula [Wherein, X is a structural formula in gel permeation chromatographic analysis of the epoxy resin. Wherein Y is the peak area of the compound (A) in the same analysis, and Y is the peak area of the compound (A). Is the area of all peaks other than the peak of the compound (A) and the peak of the compound (B) detected between the peak of the compound (B) and the peak of the compound (B). These X and Y were used as columns having an exclusion limit molecular weight of 20,000, a theoretical plate number of 16,000 and a length of 30 c
m column, the excluded ocular molecular weight is 60,000, and the number of theoretical plates is 16,000.
The values are measured using a column in which a 0 cm column is connected in series, using tetrahydrofuran as a moving bed at a flow rate of 1 ml / min, and using a 254 nm ultraviolet detector. The peak area ratio (R) of the gel permeation chromatographic analysis represented by the formula (1) is 0.05 or less, and the melting cleaving temperature measured at a heating rate of 5 ° C./min using a microscope is 88 ° C. or more , An epoxy resin powder composition characterized by using an epoxy resin at a temperature of not more than ° C. (2) The epoxy resin powder composition according to claim 1, wherein a novolak type phenol resin is contained as a curing agent.