JP3230054B2 - Process for producing novolak type epoxy resin and novolak type epoxy resin composition - Google Patents

Description

The present invention relates to a method for producing a novolak-type epoxy resin having excellent heat resistance, toughness, and moisture resistance, and to a novolak-type epoxy resin composition using the epoxy resin. Yes, molding materials for electronic parts encapsulation, insulating powder coatings, electrical laminates,
It is extremely useful for applications such as adhesives and carbon fiber reinforced plastic matrices.

[Conventional technology]

Epoxy resins can be cured with various curing agents to give cured products with excellent mechanical properties, water resistance, chemical resistance, electrical properties, etc., and can be used as adhesives, paints, laminates, molding materials It is used in a wide range of fields, such as casting materials.

Among the epoxy resins, the most general-purpose epoxy resins include liquid and solid bisphenol A type epoxy resins obtained by reacting bisphenol A with epichlorohydrin.

Further, as the epoxy resin having good heat resistance, there is a so-called polyfunctional epoxy resin having more than two epoxy groups per molecule, and typical examples thereof include a phenol novolak type epoxy resin and a cresol novolak type epoxy resin. Novolak type epoxy resin; polyglycidylamine type epoxy resin such as tetraglycidyl / diaminodiphenylmethane.

[Problems to be solved by the invention]

However, bisphenol A type epoxy resins have no more than two epoxy groups per molecule,
It has the disadvantage that the crosslinking density at the time of curing is low and the heat resistance is not always sufficient.

In addition, polyfunctional epoxy resins have the disadvantage that, although heat resistance is improved, they are generally hard and brittle. And recently, especially in the fields of epoxy resin for electronic parts and epoxy resin for carbon fiber reinforced plastic,
There is an increasing demand for a heat-resistant epoxy resin having further improved moisture resistance.

[Means for solving the problem]

The present inventors have conducted intensive studies to improve the above-mentioned drawbacks and inadequate performance of the conventional epoxy resin.
A novolak epoxy obtained by epoxidizing a novolak resin having a structure in which a naphthol skeleton is linked via a methylene bond and containing a special novolak compound having at least three hydroxyl groups in one molecule with epihalohydrin; The present inventors have found that a novolak-type epoxy resin composition comprising a resin and a curing agent has good heat resistance, and also has excellent toughness and moisture resistance, and has completed the present invention.

That is, the present invention provides: (In the formula, X is a monovalent phenol structure or a condensed polycyclic compound structure having two or more phenolic hydroxyl groups.
The methylene group in the general formula 1 is bonded to the aromatic ring in the phenol compound structure or the polycyclic compound structure,
The substitution position of the hydroxyl group may be the same as or different from the aromatic ring substituted by methylene on the naphthalene ring. Further, n is an integer of 1 or 2. A) a novolak resin (A) containing the novolak compound (a) represented by 15% by weight or more with epihalohydrin (B);
And the following general formula 1 (In the formula, X is a monovalent phenol structure or a condensed polycyclic compound structure having two or more phenolic hydroxyl groups.
The methylene group in the general formula 1 is bonded to the aromatic ring of the phenol compound structure or the polycyclic compound structure;
The substitution position of the hydroxyl group may be the same as or different from the aromatic ring substituted by methylene on the naphthalene ring. Further, n is an integer of 1 or 2. A) a novolak resin (A) containing a novolak compound (a) represented by the formula (1) in a proportion of 15% by weight or more with an epihalohydrin (B); And a novolak-type epoxy resin composition.

It is a component for forming a monovalent phenol structure or a condensed polycyclic compound structure having two or more phenolic hydroxyl groups in the general formula 1, and has two or more monovalent phenol compounds which are raw material components of the novolak resin A. The fused polycyclic compound is not particularly limited, for example, phenol,
Cresol, butylphenol, octylphenol,
Monohydric phenols such as nonylphenol; 1,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,2,1
Condensed polycondensed compounds having two or more phenolic hydroxyl groups, such as 0-anthracentriol, may be mentioned.

Above all, monohydric phenols and condensed polycyclic compounds having two or more phenolic hydroxyl groups are preferable from the viewpoint of excellent fluidity and workability is improved, and cresol is particularly preferable from the viewpoint of excellent fluidity, and the obtained cured 1,6-dihydroxynaphthalene is particularly preferred in that it has excellent heat resistance.

The following general formula 1 used in the present invention: (In the formula, X is a monovalent phenol structure or a condensed polycyclic compound structure having two or more phenolic hydroxyl groups.
The methylene group in the general formula 1 is bonded to the aromatic ring in the phenol compound structure or the polycyclic compound structure, and the substitution position of the hydroxyl group is the same as the aromatic ring substituted by methylene on the naphthalene ring. Or different.
Further, n is an integer of 1 or 2. The novolak resin (A) containing the novolak compound (a) represented by
For example, to a monohydric phenol compound or a condensed polycyclic compound having two or more phenolic hydroxyl groups, formaldehyde or a formaldehyde-generating substance is added in the presence of a basic catalyst such as NaOH or KOH, and reacted at about 50 ° C. for several hours. As a monomethylol compound or polymethylol compound, the salt generated by neutralizing the basic catalyst is then removed by washing with water, and β-naphthol is added to the mixture to raise the temperature, and the mixture is heated in the presence of an acidic catalyst such as oxalic acid. To give unreacted β-naphthol at 180 to 200 ° C. under reduced pressure.

The novolak resin (A) thus obtained can be obtained by selecting the type of the monohydric phenol compound, the condensed polycyclic compound having two or more phenolic hydroxyl groups, and the amount of β-naphthol added thereto, Compound (a)
Can be adjusted as appropriate, and the average number of hydroxyl groups of the contained molecules, that is, the number of functional groups can be controlled to a desired degree of polyfunctionality. It is easy to control the number of epoxy groups in the resin, and it is possible to increase the crosslink density during curing to achieve high heat resistance. Further, the naphthalene skeleton itself has a structure excellent in heat resistance, and since it is hydrophobic, water resistance is also improved. Further, there is an effect of improving heat resistance and toughening due to the cohesive force of the naphthalene skeletons.

Β-naphthol used here has a reactive active site of 2
Since the number of reactive active sites is as small as one as compared to α-naphthol having no one and the novolak compound a) produced during the production of the novolak resin (A) does not have a high molecular weight, the number of hydroxyl groups can be easily controlled and the raw material is inexpensive. Therefore, it is particularly preferable.

The content of the novolak compound (a) contained in the novolak resin (A) is 15% by weight or more,
Among them, 25% by weight or more is particularly preferable in terms of excellent heat resistance, toughness, and moisture resistance. Although the content of the novolak compound (a) may be 100% by weight, it is difficult to industrially produce only the novolak compound (a).
It is not always necessary to set the weight%.

In the present invention, when producing the novolak resin (A),
Within the range not deteriorating heat resistance, toughness and moisture resistance, β-
It is also possible to use other compounds having a phenolic hydroxyl group together with naphthol, for example, bisphenols such as bisphenol A, bisphenol F, tetrabromobisphenol A, resorcin, hydroquinone or 1,3,5-trihydroxyl. Polyhydric phenols such as benzene, 1,6-dihydroxynaphthalene,
Examples thereof include condensed polycyclic compounds having two or more phenolic hydroxyl groups such as 2,7-dihydroxynaphthalene and 1,2,10-anthracentriol.

Epoxidation of the novolak resin (A) thus obtained may be carried out by reacting the novolak resin (A) with epihalohydrin (B). This reaction may be performed according to, for example, a conventionally known method for obtaining a novolak-type epoxy resin from a novolak resin and epihalohydrin.

The epihalohydrin used here includes, for example, epichlorohydrin, methyl epichlorohydrin, epibromohydrin and the like, but usually epichlorohydrin is used.

The novolak-type epoxy resin composition of the present invention can be easily obtained by mixing the epoxidized novolak resin (A), a curing agent, and, if necessary, a curing accelerator. If necessary, other known and commonly used epoxy resins may be used in combination with the novolak type epoxy resin of the present invention.

The curing agent used in the present invention is not particularly limited, and any compound commonly used as a curing agent for epoxy resins can be used.

Representative curing agents include aliphatic polyamines such as triethylenetetramine; alicyclic polyamines such as bis (3-methyl-4-aminocyclohexyl) methane; aromatic polyamines such as diaminodiphenylmethane and diaminodiphenylsulfone. A novolak-type phenolic resin;
Polybasic anhydrides such as methylhexahydrophthalic anhydride and benzophenonetetracarboxylic dianhydride; polyamidoamine resins and modified products thereof; latent curing agents such as imidazole, dicyandiamide, boron trifluoride-amine complex, and guanidine derivatives Among them, diaminodiphenylmethane, diaminodiphenylsulfone, novolak-type phenol resin, dicyandiamide, and polybasic acid anhydride are preferable.

These curing agents may be used alone or in combination of two or more.

The amount of the curing agent used is equivalent to the number of epoxy groups contained in one molecule of the epoxy resin, the number of active hydrogens such as amino groups or imino groups, phenolic hydroxyl groups, or the number of acid anhydride groups in the curing agent. The amount in the vicinity is common.

When a curing agent is used, a curing accelerator can be used as appropriate.

The curing accelerator that can be used in the present invention is not particularly limited, and any of those commonly used as curing accelerators for epoxy resins can be used.

Typical curing accelerators include tertiary amines such as dimethylbenzine amine, imidazole-based compounds such as 2-thymerimidazole, and organic phosphorus compounds such as triphenylphosphine.

In the novolak type epoxy resin composition of the present invention, if necessary, various known and commonly used additives such as a filler, a colorant, a flame retardant, a release agent or a silane coupling agent may be added and blended. it can.

Representative examples of the filler include silica powder, zircon silicate, alumina, calcium carbonate, quartz powder, zircon oxide, talc, clay, barium sulfate, asbestos powder, and milled glass. Examples include carbon black, etc., typical examples of flame retardants include antimony trioxide, and typical examples of release agents include carnauba wax, and typical examples of silane coupling agents. Is aminosilane or epoxysilane.

The novolak-type epoxy resin composition of the present invention thus obtained gives a cured product having excellent heat resistance, toughness and moisture resistance.

The novolak type epoxy resin composition of the present invention can
Electrical insulating materials such as electronic component sealing materials, insulating varnishes, laminates, and insulating powder coatings; laminates for printed wiring boards and adhesives for structural materials such as prepregs, conductive adhesives and honeycomb panels; glass fibers And fiber reinforced plastics using various reinforcing fibers such as carbon fibers and aramid fibers, and prepregs thereof; and resist inks.

Next, the present invention will be specifically described with reference to Synthesis Examples, Examples and Comparative Examples. In the following, all parts and percentages are based on weight (excluding tensile elongation).

Synthesis Example 1 (Synthesis of novolak type epoxy resin) To 108 g (1 mol) of orthocresol and 167 g (2 mol) of a 36% formalin aqueous solution, 2 g of NaOH was added as a catalyst, and
The reaction was carried out at a temperature of 3 ° C. for 3 hours to synthesize a dimethylolated product of orthocresol, and then the NaOH catalyst was neutralized with hydrochloric acid and then washed with water.

Further, 288 g (2 mol) of β-naphthol is added, 2 g of oxalic acid is added as a condensation reaction catalyst, and the temperature is raised to 150 ° C. while distilling at normal pressure, and finally, vacuum distillation is performed at 200 ° C. and 10 mmHg for 1 hour. By Novolak resin (A-1) containing 30% of the following components: Next, the novolak resin (A
-1) 463 g of epichlorohydrin was added to 140 g, and 220 g of a 20% aqueous sodium hydroxide solution was added dropwise over 5 hours while stirring at 80 ° C. After further stirring at 80 ° C. for 1 hour, the aqueous layer was discarded, and excess epichlorohydrin was recovered by distillation.
The reaction product thus obtained is treated with methyl isobutyl ketone.
After dissolving in 200 g, water was added and washed with water, and then water was removed by azeotropic distillation to obtain a methyl isobutyl ketone solution of a novolak type epoxy resin. Next, the solution was filtered, the sodium chloride crystals were separated by filtration, and methyl isobutyl ketone was distilled off to obtain a novolak-type epoxy resin (I) having a softening point of 85 ° C and an epoxy equivalent of 235.

Synthesis Example 2 (Synthesis of novolak-type epoxy resin) To 228 g (1 mol) of bisphenol A and 167 g (2 mol) of a 36% formalin aqueous solution, 3 g of NaHO was added as a catalyst and reacted at 50 ° C. for 3 hours to synthesize a dimethylolated bisphenol A. Then, the NaOH catalyst was neutralized with hydrochloric acid and washed with water. Further, 288 g (2 mol) of β-naphthol was added, 2 g of oxalic acid was added as a condensation catalyst, the temperature was raised to 150 ° C. while distilling at normal pressure, and finally distillation was performed at 200 ° C. and 10 mmHg for 1 hour under reduced pressure. , Resin containing 33% in total (A-
2) was obtained. Next, a novolak-type epoxy resin (II) having a softening point of 93 ° C and an epoxy equivalent of 230 was obtained in the same manner as in Synthesis Example 1 except that 135 g of the novolak resin (A-2) thus obtained was used.

Synthesis Example 3 (Synthesis of novolak epoxy resin) 94 g (1 mol) of phenol, 36% formalin aqueous solution 208
g (2.5 mol) was added with 2 g of NaOH as a catalyst, and reacted at 50 ° C. for 3 hours to synthesize a methylolated phenol. Then, the NaOH catalyst was neutralized with hydrochloric acid and then washed with water. Further, 360 g (2.5 mol) of β-naphthol is added, 2 g of oxalic acid is added as a condensation reaction catalyst, the temperature is raised to 150 ° C. while distilling at normal pressure, and finally vacuum distillation is performed at 200 ° C. and 10 mmHg for 1 hour. By Resin containing 35% in total (A-
3) was obtained.

Next, the novolak resin (A-
3) A novolak-type epoxy resin (III) having a softening point of 90 ° C. and an epoxy equivalent of 248 was obtained by performing a reaction treatment under the same conditions as in Synthesis Example 1 except that 140 g was used.

Synthesis Example 4 (Synthesis of novolak type epoxy resin) The same procedure as in Synthesis Example 1 was carried out except that the amount of β-naphthol added was 360 g (2.5 mol) and the final distillation conditions were 200 ° C. and 1 mmHg for 1 hour. Novolak resin (A-4) containing 60% of the following components: Next, the novolak resin (A
-4) Softening point in the same manner as in Synthesis Example 1 except that 150 g was used.
A novolak-type epoxy resin with an epoxy equivalent of 243 at 90 ° C (I
V).

Synthesis Example 5 (Synthesis of novolak type epoxy resin) 1,6-dihydroxynaphthalene 160 g (1 mol), β-
Naphthol 288g (2mol), 36% formalin aqueous solution 167g
(2 mol) was added with 3 g of NaOH as a catalyst and reacted at 80 ° C. for 3 hours.

Next, the NaOH catalyst was neutralized with hydrochloric acid and washed with water to obtain a novolak resin (A-5) containing 50% of the following components. Next, except that 130 g of the novolak resin thus obtained was used, the softening point was 95 ° C and the epoxy equivalent was the same as in Synthesis Example 1.
220 novolak type epoxy resin (V) was obtained.

Examples 1 to 5 and Comparative Examples 1 to 3 The novolak-type epoxy resins (I) to (V) of the present invention obtained in Synthesis Examples 1 to 5 and a phenol novolak-type epoxy resin which is an epoxy resin for comparison (semi-solid) Mold, softening point 52 ° C, viscosity 420 poise, epoxy equivalent 180), orthocresol novolak type epoxy resin (softening point 83 ° C, epoxy equivalent 210) and liquid bisphenol A type epoxy resin (25 ° C, viscosity 11000cps, epoxy equivalent 188) respectively Methyltetrahydrophthalic anhydride is used as a curing agent, and 2-ethyl-4-methylimidazole is used as a curing accelerator. One epoxy group has one acid anhydride group per one epoxy group.
After blending with the composition shown in Table 1 so as to obtain individual pieces, cured at 100 ° C. for 2 hours and then at 170 ° C. for 3 hours,
A test piece having a thickness of 3 mm was used, and the heat deformation temperature, bending strength, tensile strength and tensile elongation were measured according to JIS K-6911. Further, the water absorption after 5 hours of boiling was measured. The results are shown in Table 1 as Examples 1 to 5 and Comparative Examples 1 to 3, respectively.

[Effect of the Invention] The novolak-type epoxy resin composition containing the novolak-type epoxy resin and the effect agent obtained by the production method of the present invention has good heat resistance, and also has excellent toughness and moisture resistance.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08G 59/08

Claims (3)

(57) [Claims] 1. The following general formula 1. (In the formula, X is a monovalent phenol structure or a condensed polycyclic compound structure having two or more phenolic hydroxyl groups.
The methylene group in the general formula 1 is bonded to the aromatic ring in the phenol compound structure or the polycyclic compound structure,
The substitution position of the hydroxyl group may be the same as or different from the aromatic ring substituted by methylene on the naphthalene ring. Further, n is an integer of 1 or 2. A method for producing a novolak-type epoxy resin, comprising reacting a novolak resin (A) containing a novolak compound (a) represented by the formula (1) in a proportion of 15% by weight or more with epihalohydrin (B). 2. The novolak resin (A) is reacted with a monohydric phenol compound or a condensed polycyclic compound having two or more phenolic hydroxyl groups and formaldehyde in the presence of a basic catalyst, and then neutralized. 2. The process according to claim 1, which is obtained by reacting with β-naphthol in the presence of an acidic catalyst. 3. The following general formula 1. (In the formula, X is a monovalent phenol structure or a condensed polycyclic compound structure having two or more phenolic hydroxyl groups.
The methylene group in the general formula 1 is bonded to the aromatic ring of the phenol compound structure or the polycyclic compound structure;
The substitution position of the hydroxyl group may be the same as or different from the aromatic ring substituted by methylene on the naphthalene ring. Further, n is an integer of 1 or 2. A) a novolak resin (A) containing the novolak compound (a) represented by the formula (1) in a proportion of 15% by weight or more with an epihalohydrin (B); A novolak-type epoxy resin composition characterized in that: