JPH05105734A - Amino group-containing novolak resin and its production - Google Patents

Abstract

PURPOSE:To produce the subject resin useful for synthesis of heat-resistance resins, e.g. a curing agent for epoxy resins, addition type polyimide resins, etc., by nitrating a p-alkylphenol-phenols-co-condensed novolak resin and then reducing it. CONSTITUTION:A mixture of a p-alkylphenol and a phenol (e.g. p-t-butylphenol) is reacted with formaldehyde in the presence of an acid catalyst (e.g. hydrochloric acid or oxalic acid) and dehydrative concentration is subsequently carried out by heating under a reduced pressure. Concentrated nitric acid is then added thereto under ice cooling to nitrate it. The nitrated compound is subsequently reduced by using iron-hydrochloric acid, etc., thus obtaining the objective amino-containing novolak resin of the formula ((m) and (n) are 1-20; Order of aminophenol and phenol is arbitrary).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amino group-containing novolac resin useful for the synthesis of heat resistant resins such as epoxy resin and addition type polyimide curing agents, and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Phenolic resins are resins obtained by reacting phenols with formaldehyde in the presence of an acidic or basic catalyst. The former is called novolak resin and the latter is called resole resin. The novolac resin is not only useful as a molding material or a resin for casting such as resin coated sand, but is also produced in large quantities as a curing agent for an epoxy resin used as a semiconductor encapsulant. Resole resin is used as a water-soluble phenol resin for a binder of glass fiber, a binder of wood chips, and the like, and is mass-produced for uses such as a phenol resin for laminated boards. However, the raw materials of these phenolic resins are limited to phenols, the functional group of the novolak resin is a phenolic hydroxyl group, and the functional group of the resole resin has a methylol group and a dimethylene ether group in addition to the hydroxyl group, Except for hydroxyl group, it is accompanied by elimination reaction of water and formaldehyde. Therefore, it cannot be used for other purposes such as a curing agent for epoxy resin such as resole resin and novolac resin. On the other hand, it was thought that by introducing a highly reactive functional group into the novolac resin, it is possible to further improve the properties of the resin that can be modified with the novolac resin, such as epoxy resin and polyimide. However, it has been difficult to introduce another functional group into the novolak resin, and it has been difficult to introduce an amino group. The conventionally considered method for introducing an amino group into a novolak resin is nitration of the novolak resin and its reduction, but the nitration reaction cannot be controlled and a useful amino group-containing novolak cannot be obtained. Further, when p-aminophenol or the like is used as a raw material, a linear novolac resin cannot be synthesized because the amino group also reacts with formaldehyde, and when p-nitrophenol or the like is used as a raw material, the electron-withdrawing property of the nitro group is reduced. For p
-Nitrophenol does not react with formaldehyde to give the desired product. Therefore, as a result of intensive studies, the present invention has been achieved.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an amino group-containing novolak type phenol resin useful as a curing agent for epoxy resins.

[0004]

That is, the present invention provides a novolac type phenolic resin containing an amino group represented by the following general formula [I].

[Chemical 2] (However, m and n each represent an integer of 1 to 20, and may be the same or different. The order of binding aminophenol and phenol is arbitrary.) The present invention will be described in detail. -Reacting a mixture of alkylphenols and phenols with formaldehyde under acidic catalyst,
A co-condensed novolak resin of p-alkylphenols and phenol is synthesized. When nitrated with nitric acid-sulfuric acid, p
-Alkyl is selectively nitrated. This is reduced by a conventional method such as iron-acetic acid, zinc-hydrochloric acid, catalytic reduction method or the like to obtain the desired p-aminophenol-introduced novolak resin of the general formula [I] of the present invention. ..

The synthetic scheme of the amino group-containing novolak resin obtained in the present invention is shown below.

[Chemical 3]

[Chemical 4]

The phenols used in the present invention are p-te
Examples include rt-butylphenol, p-iso-propylphenol, p-cresol, m-cresol, o-cresol, p-nonylphenols. Formaldehyde sources include formalin, paraform, trioxane and the like.

The reaction of a mixture of alkylphenols and phenols with formaldehyde is carried out in the presence of an inorganic acid such as hydrochloric acid or sulfuric acid or an organic acid such as p-toluenesulfonic acid, oxalic acid or acetic acid as in general novolac resins. After completion of the reaction, the mixture is heated under reduced pressure for dehydration concentration and the solvent and unreacted raw materials are distilled off. A solid novolac resin (A) is obtained by cooling the obtained reaction product. Alternatively, (A) can also be obtained by a method in which after dehydration and concentration, a solvent is added to form a solution, which is poured into a large amount of water and reprecipitated. Then, the nitration reaction of (A) is completed by gradually adding concentrated nitric acid to (A) while ice-cooling, and the precipitate is collected by pouring into a large amount of water and the nitrated novolak resin (B ) Get. Further, (B) is iron-hydrochloric acid, iron-acetic acid,
The amino group-containing novolak resin [I], which is the object of the present invention, is obtained by reduction by a conventional reduction method such as a catalytic reduction method. The compounding ratio for producing the co-condensate of p-alkylphenol and phenol is 95-35: 5-65 of p-alkylphenol: phenol, and particularly 60-40: 4.
It is preferably 0 to 60. When the amount of phenol is more than 35 mol%, the nitration reaction occurs even in the phenol skeleton, and the amino group-containing novolac resin having stereoregularity cannot be synthesized. The amount of formaldehyde with respect to the total amount of p-alkylphenol and phenol varies depending on the amount of phenol to be co-condensed, but it is necessary to set the amount so that gelation does not occur during the synthesis of the novolak resin.

[0008]

It was discovered that a nitration of a p-alkylphenol-introduced novolak resin causes a substitution reaction quantitatively and selectively at the position of the alkyl group, which led to the present invention. The amino group-containing novolac resin obtained in the present invention has a higher cross-linking density than the novolac resin conventionally used as a curing agent for epoxy resins. Therefore, the heat-resistant epoxy resin and the addition-type polyimide are improved in heat resistance. It is useful.

[0009]

EXAMPLES The present invention will be specifically described below with reference to examples. Synthesis Example 1 (1) Synthesis of co-condensate of p-tert-butylphenol and phenol p-tert-butylphenol 150.22 g (1 mol), phenol 94.12 g (1 mol), 37% formalin 146.09 g (1. 8 mol) and 0.9 g of oxalic acid were placed in a 1-liter three-necked flask and refluxed for 4 hours with stirring. The upper layer aqueous solution portion was removed by decantation, and the product was further dehydrated under reduced pressure with an evaporator. The residual novolak resin was dissolved again in acetone, poured into water and reprecipitated to obtain a purified novolak resin. Yield 220 g (2) Synthesis of p-nitrophenol novolac 350 ml of concentrated nitric acid was placed in a 500 ml Erlenmeyer flask, cooled to −5 to 0 ° C. in an ice-water bath, and stirred well, while stirring p-tert-butylphenol prepared in (1). 40 g of phenol co-condensed novolak was gradually added to the whole amount over about 1 hour, and the reaction was continued by further stirring at 0 ° C. for 5 hours. After completion of the reaction, the reaction solution is poured into 1 liter of cold water to form a precipitate.
The precipitate was separated by filtration, washed thoroughly with cold water, dried at 50 ° C., further washed with chloroform, and dried again to obtain a precipitate nitrophenol novolak. Yield 34.5 g (3) Synthesis of amino group-containing novolac resin 20 g of nitrophenol novolac synthesized in (2) was placed in a 500 ml three-neck flask containing 30 g of granular tin, 50 ml of concentrated hydrochloric acid and 300 ml of methanol, and was placed under a nitrogen atmosphere for 4 hours. Brought to reflux. Next, granular tin was removed by decantation, and the reaction solution was poured into 500 ml of acetone and reprecipitated. The precipitated solid was collected by filtration, washed repeatedly with acetone, and air-dried to obtain aminophenol novolac. Yield 16.2g

Synthesis Examples 2-3 An amino group-containing novolak resin was synthesized in the same manner as in Synthesis Example 1 except that the compounding molar ratio of p-tert-butylphenol and phenol was changed as shown in Table 1. It was confirmed that the amino group content was proportional to the content of p-tert-butylphenol.

[0011]

[Table 1]

Example 1 Amino group-containing novolak resin 9.4 synthesized in Synthesis Example 1
g, bisphenol A type epoxy resin 15.4 g, 2-
Ethyl-4-methylimidazole 0.1 g in a small amount of DM
It was dissolved in F, made into a B stage on a hot plate, and then cooled and pulverized. 50 x 50 x with the powder sandwiched between stainless end plates
It was filled in a spacer of 1.5 t and heated and pressed at 200 ° C. and 5 MPa to prepare a resin plate.

Examples 2 to 3 The amino group-containing novolak resins synthesized in Synthesis Examples 2 to 3 were processed in the same manner as in Example 1 to prepare resin plates. The compounding amount of the amino group-containing novolak resin is shown in Table 2.

Comparative Example 1 Instead of the amino group-containing novolac resin of Example 1, 11.3 g of phenol novolac resin was used, and a resin plate was prepared in the same manner as in Example 1. The thermal expansion coefficient and the glass transition point (Tg) of the obtained resin plate were determined with a thermomechanical measuring device (TMA) at a temperature rising rate of 10 ° C./min. The results are shown in Table 2.

[0015]

[Table 2]

[0016]

The amino group-containing novolak resin, which is difficult to synthesize from phenols having a functional group such as p-aminophenol or p-nitrophenol as a starting material, has p-alkylphenols as a starting material. It became possible to synthesize easily. Moreover,
By appropriately co-condensing p-alkylphenols and phenol, it has become possible to synthesize an amino group-containing novolak resin having an adjusted amino group content. The synthesized amino group-containing novolak resin is useful as a curing agent for an epoxy resin having an increased crosslink density, and is also useful as a modifier for improving the heat resistance of a maleimide resin.

Claims (3)

[Claims] 1. A novolac-type phenol resin containing an amino group represented by the general formula [I]: (However, m and n represent 1 to 20 and may be the same or different from each other. Further, the binding order of aminophenol and phenol is arbitrary.) 2. A method of nitrating a co-condensed novolak resin of p-alkylphenols and phenol obtained by reacting a mixture of p-alkylphenols and phenol, formaldehyde and an acidic catalyst, and then reducing it to give amino groups. A method for producing a novolak resin containing a characteristic amino group. 3. A p-alkylphenol is p-tert-
Claim 2 characterized in that it is butylphenol
A method for synthesizing an amino group-containing novolak resin according to the item.