JPS6138930B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel and useful method for producing a polyfunctional epoxy resin, including a precondensation step (first step) in which polyvalent phenols are precondensed with an epoxy resin obtained from polyvalent phenols and epichlorohydrin; Thereafter, the precondensate obtained here is co-condensed with a phenolic resin obtained from phenol and/or substituted phenols and a formadehyde supply material, and a novolak type epoxy resin obtained from epichlorohydrin (second co-condensation step). It is characterized by consisting of In general, epoxy resins have excellent corrosion resistance, adhesive properties, heat resistance, electrical properties, curing properties, and other properties due to their unique structure. Not only does it have a wide range of uses, including agents, electrical parts, and civil engineering buildings, but it is also extremely important industrially, as it can be used as a modifying agent for various resins. The reality is that even higher performance is required in each field of use. For example, in the field of coating materials, from liquid low molecular weight bisphenol A type epoxy resins to solid high molecular weight bisphenol A type epoxy resins, amine curing agents, acid anhydride curing agents, acid anhydride curing agents, etc. Can paints, pre-coated metal paints, etc. can be cured at room temperature or by heating in combination with curing agents, phenolic resins, melamine resins, acrylic resin curing agents, latent curing agents, and other curing agents.
Used in tar epoxy resin paints, pure epoxy paints, and others. However, not only are long-term corrosion protection and heat resistance insufficient, but also resistance to organic and inorganic acids and alkalis, as well as various solvents, is particularly inadequate for cold-curing coating materials. , because the above-mentioned performances are insufficient,
The current situation is that there is a strong demand for measures to improve these various performances. In addition, in the so-called electrical field such as electrical insulation, difficult-to-use bisphenol A-type epoxy resins are used in combination with various curing agents for casting, laminating, embedding, sealing, and other applications, as mentioned above. Not only can a brominated epoxy resin with flame resistance be used, but also a combination of a novolak resin obtained from the above-mentioned phenol and/or substituted phenols and a formadehyde supply substance and epichlorohydrin can be used to improve heat resistance. Although the resulting so-called novolak type epoxy resins are widely used, their applications are severely limited because they are not compatible with polyamide hardeners, and they are also difficult to use with compatible hardeners. Although the combination certainly increases the cured density and the degree of heat resistance, on the other hand, these cured resins generally become brittle, and are susceptible to "warps" and "cracks" during post-processing or repeated heating and cooling. The current situation is that the field of use is restricted due to the occurrence of "", and moreover, there is a high incidence of defective products. However, in view of the current situation as described above, the present inventors have conducted extensive research over many years, and as a result, while retaining the advantages of bisphenol A type epoxy resin, which is currently most commonly used, we have developed a new heat-resistant epoxy resin. This is a new product that has improved hardness and chemical resistance, and also has the heat resistance of novolak type epoxy resin, and is even more flexible and has significantly improved compatibility with various hardening agents. We have discovered a useful polyfunctional novolac type epoxy resin and have completed the present invention. That is, the present invention involves a step of precondensing an excess of polyhydric phenols onto epoxy resin A obtained from polyhydric phenols and epichlorohydrin (that is, a precondensation step), and then a precondensation product obtained here. and a step of co-condensing a novolak-type phenolic resin obtained from phenol and/or substituted phenols and a formadehyde supplying substance with a novolak-type epoxy resin B obtained from epichlorohydrin (that is, a co-condensation step). The present invention provides a method for producing a polyfunctional novolac type phenolic resin, which comprises the following steps. Here, the polyhydric phenols used to obtain the epoxy resin A, or the polyhydric phenols further used as a condensation component for the precondensation, are 2,2'-bis(p-hydroxyphenyl). ) Bis(p-hydroxyphenyl) alkanes such as propane (commonly known as "bisphenol A") or bis(p-hydroxyphenyl)methane (commonly known as "bisphenol F") and their nuclear halogen substituted products; 1 , 3-dihydroxybenzene (commonly known as "resol"), and their alkylated products or nuclear halogen-substituted products; and all polyhydric phenols, including diphenols such as bisphenolsulfone. It is a thing,
Among these, the above-mentioned bisphenol A or bisphenol F is the most common. In addition, it may be more useful to use monophenols such as phenol, cresol, or octylphenol; and a dinuclear or higher phenolic resin obtained from these monophenols and a formaldehyde supplying substance as described below. Therefore, the term "polyhydric phenols" as used in the present invention should be understood in this way. In order to obtain the above-mentioned epoxy resin A from such polyhydric phenols and epichlorohydrin, for example, the method described in "Production and Application of Epoxy Resins" edited by Kobunshi Kagaku Kankai (published on November 10, 1960) You can follow this method. In carrying out the precondensation step, which is the first step of the method of the present invention, the term "precondensed" means that the epoxy equivalent of the precondensate obtained through such step is at least 3000 g/equivalent (hereinafter referred to as
It is abbreviated as 3000g/eq. ), and in this precondensation step, it is necessary to make a stoichiometrically excessive amount of polyhydric phenols present in the presence of the epoxy resin A in order to carry out the condensation. In other words, it is necessary to have one or more phenolic hydroxyl groups present in the polyhydric phenols for each epoxy group present in the epoxy resin A, and more preferably, one or more phenolic hydroxyl groups present in the polyhydric phenols. A suitable range is 1.2 to 4.0 hydroxyl groups for each hydroxyl group. Thus, in the first step, the precondensate can be obtained by simply heating the above-mentioned epoxy resin A and the above-mentioned polyhydric phenols, but by using an appropriate catalyst and selecting an appropriate temperature. The latter method is rather recommended since a precondensate can be easily obtained by this method. Typical catalysts that promote these reactions include inorganic alkaline hydroxides or halides such as lithium hydroxide or sodium hydroxide; trimethylamine, triethylamine, benzylmethylamine, N-methylpiperazine or N-methylmorpholine. Tertiary amines or their hydrochlorides such as; quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide or phenyltrimethylammonium chloride; imidazole compounds such as imidazole or 2-ethylimidazole; ; acidic phosphorus compounds such as triphenylphosphone; inorganic alkali salts of organic carboxylic acids such as calcium acetate; or quaternary ammonium salt type ion exchange resins.
By adding appropriate amounts of these, the reaction can be effectively promoted, and on the other hand, the reaction temperature is usually 50 to 50℃.
A temperature of 260°C, preferably 100-200°C is suitable. In addition, at this time, the reaction can be carried out by diluting with a known and commonly used appropriate solvent, which is a useful method. On the other hand, the above-mentioned cocondensation step, which is the second step of the method of the present invention, is a step in which the precondensate obtained in the previous precondensation step is further reacted with a novolak type epoxy resin. Epoxy resin B refers to a resin obtained by further reacting epichlorohydrin with a phenolic resin obtained from phenol and/or substituted phenols and a formaldehyde supply substance, and is a typical substituted phenol. Examples include cresol or octylphenol, while typical formaldehyde supply materials include formalin, paraformaldehyde, or hexamethylene diamine. In this way, the second step of co-condensing the novolak type epoxy resin B with the precondensate is also a reaction between the phenolic hydroxyl group and the epoxy group, so that the precondensate is obtained in the first step. This can be done in the same way as in the case. That is, the ratio of the epoxy resin B to the precondensate is such that the phenolic hydroxyl group of the precondensate is 0.01 to 0.5 chemical equivalent (that is, 0.01) to one chemical equivalent of epoxy group (that is, one epoxy group) of the resin B. ~0.5 pieces), preferably within the range of 0.02 to 0.4 chemical equivalents (that is, 0.02 to 0.4 pieces). Other reaction catalysts, reaction temperatures, etc. may be the same as in the first step. If the number of phenolic hydroxyl groups is less than 0.01, the compatibility with amine curing agents and the flexibility of the cured product will not be sufficient, whereas if it exceeds 0.5, the heat resistance of the cured product will only decrease. However, both are unfavorable because they tend to cause gelation during the reaction. The thus obtained polyfunctionally modified novolak type epoxy resin, as in the case of conventional bisphenol A type epoxy resin, contains aliphatic polyamine, aromatic polyamine, cyanoethylated polyamine, glycidyl ether x polyamine adduct, polyamide, polyamide.・Amino group-containing compounds such as adducts, dicyandiamide or acid hydrazides; (anhydrous) carboxyl group-containing compounds such as carboxylic acids or their acid anhydrides or acid-rich polyesters; Lewis acid metal halides; phenolic resins, urea resins By curing in combination with known and commonly used curing agents such as melamine resins and acrylic resins, they can be preferably used for various applications such as coatings, civil engineering, adhesives, and electrical applications. First, it is useful in the field of coatings or adhesives that require a high degree of durability against acids, alkalis, solvents, gases, etc., or in the electrical field that requires heat resistance, flexibility, electrical insulation, etc. Next, the present invention will be specifically explained using reference examples, examples, and comparative examples. Unless otherwise specified, all parts and percentages are based on weight, and hydroxyl groups and hydroxyl equivalents are Each term shall mean a phenolic hydroxyl group and a phenolic hydroxyl group equivalent. Further, the units of epoxy equivalent and phenolic hydroxyl group equivalent are grams/equivalent, but in the following, this unit will be omitted in both cases. Reference Example 1 (Example of preparation of precondensate) In a four-necked flask equipped with a stirrer, a nitrogen gas introduction device, and a thermometer, "Epicron 850" (epichlorohydrin bisphenol type A manufactured by Dainippon Ink and Chemicals Co., Ltd.) was added. Epoxy resin; epoxy equivalent =
190 parts (i.e., equivalent to one epoxy group), 228 parts (i.e., equivalent to two hydroxyl groups) of bisphenol A, and 0.2 parts of a 1% aqueous solution of caustic soda were added, and the mixture was heated to 180°C while purging with nitrogen gas. By reacting at this temperature for 5 hours, a precondensate having an epoxy equivalent of 35,000 and a hydroxyl equivalent of 414 was obtained. Hereinafter, this will be abbreviated as PC-1. Reference example 2 (same as above) 190 of "Epicron 850" in the same way as reference example 1
171 parts of bisphenol A (equivalent to 1.5 hydroxyl groups) and 0.2 parts of a 10% tetramethylammonium chloride aqueous solution at 160°C for 4 hours.
By reacting at 190°C for 2 hours, a precondensate having an epoxy equivalent of 11,000 and a hydroxyl equivalent of 722 was obtained. Hereinafter, this will be abbreviated as PC-2. Reference example 3 (same as above) The amount of bisphenol A used was 149 parts (hydroxyl group 1.3
The epoxy equivalent was 9500, the hydroxyl equivalent was 1257, and
A precondensate with a melting point (ring and ball method) of 115°C was obtained.
Hereinafter, this will be abbreviated as PC-3. Reference example 4 (same as above) except that 200 parts (equivalent to 2 hydroxyl groups) of bisphenol F was used instead of bisphenol A.
A precondensate having an epoxy equivalent of 27,000 and a hydroxyl equivalent of 390 was obtained in the same manner as in Reference Example 1. Hereinafter, this will be abbreviated as PC-4. Reference example 5 (same as above) 180 parts (one epoxy group) of “Epicron”
830'' (Epichlorohydrin Bisphenol F type epoxy resin manufactured by Dainippon Ink & Chemicals Co., Ltd.; epoxy equivalent = 180) and 150 parts (1.5 hydroxyl groups) of Bisphenol F were used.
Similarly, the epoxy equivalent is 8900 and the hydroxyl equivalent is
A precondensate named 660 was obtained. Below, this is PC-5
It is abbreviated as Example 1 In a flask similar to Reference Example 1, 60 parts of PC-1 obtained in Reference Example 1 (0.145 hydroxyl groups) and "Epiclon N-740" (epichlorohydrin-phenol formalin novolak resin manufactured by the same company) were added. 180 parts (for one epoxy group) of type polyfunctional semisolid epoxy resin; epoxy equivalent = 180), 0.24 part of 1% aqueous solution of tetramethylammonia chloride, and xylol 80
After reacting at 140℃ for 4 hours, 80 parts of methyl isobutyl ketone was added and dissolved, resulting in an epoxy equivalent (solid content) of 285 and a non-volatile content.
A polyfunctional epoxy resin varnish of 59.7% was obtained. Hereinafter, this will be abbreviated as E-1. Example 2 50 parts of PC-2 obtained in Reference Example 2 (hydroxyl group
0.07 parts), the amount of 1% tetramethylammonium chloride aqueous solution was changed to 0.23 parts, no solvent was used at all, and the reaction conditions were changed to 145°C for 6 hours. Example 1
A polyfunctional epoxy resin having an epoxy equivalent of 255 was obtained in the same manner as above. Hereinafter, this will be abbreviated as E-2. Example 3 The same operation as in Example 2 was repeated, except that the amount of PC-2 used was changed to 100 parts (for 0.14 hydroxyl groups) and the amount of 1% tetramethylammonia chloride aqueous solution used was changed to 0.28 parts. Epoxy equivalent is 325
A polyfunctional epoxy resin was obtained. Below, this is E
-Abbreviated as 3. Example 4 An epoxy equivalent of 470 was prepared in the same manner as in Example 2, except that the amount of PC-2 used was 180 parts (for 0.25 hydroxyl groups) and the amount of 1% tetramethylammonium chloride aqueous solution was changed to 0.36 parts. A polyfunctional epoxy resin was obtained. Hereinafter, this will be referred to as E-4. Example 5 220 parts of PC-3 obtained in Reference Example 3 (hydroxyl group
The procedure was the same as in Example 1, except that the amount of 1% tetramethylammonia chloride aqueous solution was changed to 0.40 parts, and the amounts of xylene and methyl isobutyl ketone were changed to 133 parts and 134 parts, respectively. The epoxy equivalent (solid content) is
480, a viscosity (Gardner method at 25°C; the same applies hereinafter) of _Z5 , and a non-volatile content of 60.1%, a polyfunctional epoxy resin varnish was obtained. Hereinafter, this will be abbreviated as E-5. Example 6 "Epiclon N-673" (cresol novolak type epoxy resin manufactured by Dainippon Ink and Chemicals Co., Ltd.; epoxy equivalent =
220) (equivalent to one epoxy group) and in place of PC-1, PC obtained in Reference Example 4 was used.
- 55 parts of 4 (corresponding to 0.14 hydroxyl groups) were used, the amount of 1% tetramethylammonium chloride aqueous solution was 0.28 parts, and the amounts of xylene and methyl isobutyl ketone were each 92 parts. A polyfunctional epoxy resin varnish having an epoxy equivalent weight (solid content) of 312, a viscosity of Y, and a non-volatile content of 60.0% was obtained in the same manner as in Example 1. Hereinafter, this will be abbreviated as E-6. Example 7 Instead of PC-4, PC- obtained in Reference Example 5 was used.
5 (0.14 hydroxyl groups), the catalyst was also changed to 0.3 parts of 1% tetramethylammonia chloride aqueous solution, xylol was changed to 103 parts, and methyl isobutyl ketone was changed to 104 parts. , the epoxy equivalent (solid content) was 350, the viscosity was Z ₂ , and the nonvolatile content was 60.0% in the same manner as in Example 6.
A polyfunctional epoxy resin varnish was obtained. Hereinafter, this will be abbreviated as E-7. While each of the polyfunctional epoxy resins or resin varnishes obtained in Examples 1 to 7 was used, a commercially available epoxy resin was used as a comparative product, and a commercially available modified polyamine curing agent "Tomide 213-A" was also used. The compatibility between the resin and the curing agent and the performance of the cured product were evaluated. The results are summarized in Table 1. The curing agent "Tomide 213-A" used here is a modified polyamine curing agent manufactured by Fuji Kasei Co., Ltd., and has an amine value of 85°C, a viscosity of W, and a nonvolatile content of 50°C. be. Compatibility is determined by blending the epoxy resin and curing agent in the proportions listed in the same table, and then mixing this with cyclohexane/xylene/n-butanol = 1/
Non-volatile content is removed using thinner with a ratio of 1/1 (weight ratio).
The compatibility was determined by observing the compatibility state in a solution state as a 50% varnish. In addition, the flexibility of the cured coating film was determined by the epoxy resin, curing agent, and
Apply thinner varnish to a polished iron plate and leave at room temperature.
After curing and drying for 10 days, a 35μ thick cured film was tested using a Dupont impact tester at 0.5Kg
Evaluations were made under the condition of 30 cm. Furthermore, cured coatings similar to those used in the above flexibility test were immersed in each of the solvents listed in the same table at room temperature for 15 days, and the coatings were evaluated and evaluated by observing the degree of swelling.

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Claims (1)

[Claims] 1. A precondensation step in which an excess of polyhydric phenols is preliminarily condensed onto epoxy resin A obtained from polyhydric phenols and epichlorohydrin, and then a phenol compound obtained from phenol and/or substituted phenols and a formadehyde supply substance is added. A method for producing a novel polyfunctional epoxy resin, comprising two steps: a co-condensation step in which a novolac type epoxy resin B obtained from a resin and epichlorohydrin is co-condensed with the precondensate obtained in the above step.