JPH04264118A - Novolac resin and its production - Google Patents

Abstract

PURPOSE:To provide a low-viscosity novolac resin useful as a raw material of an epoxy resin giving a cured article excellent in resistance to heat and humidity. CONSTITUTION:A novolac resin is prepd. by reacting a dimethylol compd. with naphthol at 40-85 deg.C in the presence of an acid catalyst and removing excess naphthol from the reaction mixture by distillation at 200 deg.C under a reduced pressure. The resin contains 30wt.% or higher trinuclear compds. and 10wt.% or lower compds. having a mol.wt. lower than that of the trinuclear compds., and is lowly viscous and useful as a raw material of an epoxy resin.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention provides a softening agent useful as a raw material for epoxy resin that provides a cured product with excellent moisture resistance and heat resistance, and as a curing agent for epoxy resin. This invention relates to a novolak type resin with a low score and its manufacturing method. [0002] JP-A-3-717 describes a novolak type resin obtained by reacting a dimethylol compound and naphthol in the presence of an acid catalyst. Problems to be Solved by the Invention In the example of JP-A-3-717, the reaction between a dimethylol compound and naphthol was
The reaction was carried out at a temperature of 0 to 95°C, and excess naphthol in the reaction mixture was removed by steam distillation. However, in this method, the reaction products are decomposed or recondensed due to the oxidation reaction under steam distillation, so the proportion of the trinuclear compound described below in the novolac type resin decreases. Furthermore, the content of a compound having a lower molecular weight than the trinuclear compound increases, and the resulting novolac type resin and its epoxidized product have a high softening point, making it impossible to obtain a low-viscosity product that is easy to handle. Furthermore, a cured product using an epoxy resin obtained by epoxidizing this novolak type resin has moisture resistance,
It has excellent heat resistance, but further improvements in moisture resistance and heat resistance are desired. [Means for Solving the Problems] Therefore, the present inventors
As a result of intensive studies to solve the above problems, the present invention has been completed. That is, the present invention provides dimethylol compounds represented by formula (1) (A) ##STR1## (wherein R represents an alkyl group having 1 to 4 carbon atoms) and naphthol. , formula (B) [0010] (wherein R represents the same meaning as above) containing 30% by weight or more of a trinuclear compound and containing a compound having a lower molecular weight than the trinuclear compound Novolak-type resin in an amount of 10% by weight or less. (2) The novolak type resin according to (1) above, wherein the total content of polynuclear compounds of hepta-nuclear or higher is 25% by weight or less. (3) The above dimethylol compound (A) and naphthol are reacted at a temperature of 40 to 85°C in the presence of an acid catalyst, and excess naphthol in the reaction mixture is removed under reduced pressure at 200°C.
The method for producing a novolak-type resin according to (1) or (2) above, characterized in that the removal is carried out by heating and distillation at a temperature of 0.degree. C. or lower. Regarding. The present invention will be explained in detail below. In the dimethylol compound (A), examples of R include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, and t-butyl group, but especially methyl group is preferred. Specific examples of the dimethylol compound (A) include 2,6-dimethylol-4-methylphenol, 2,6-dimethylol-4-t-butylphenol, 4,6-dimethylol-2-methylphenol, 4
, 6-dimethylol-2-t-butylphenol and the like. Naphthol includes α-naphthol and β-naphthol.
- Naphthol. The novolac type resin of the above (1) can be produced by reacting (dehydration condensation) the dimethylol compound (A) and naphthol, generally in the presence of an acid catalyst, and therefore has the formula (C). [0017] Contains as a main component a compound represented by the formula (wherein R represents the same meaning as above and n takes a value of 0-2), but contains 30% by weight of trinuclear compound (B). % or more, preferably 35% by weight or more, particularly preferably 40% by weight or more. The novolac type resin of the present invention also contains by-products such as decomposition products and recondensation products generated in the process of distillation, etc., but the trinuclear compound (B ) The content of lower molecular weight compounds (such as the above-mentioned by-products) is 10% by weight or less, preferably 7% by weight or less, particularly preferably 5% by weight or less. The total content of polynuclear compounds of hepta-nuclear or higher is preferably 25% by weight or less, particularly preferably 20% by weight or less. Furthermore, an X-nuclear compound is one in which the sum of the numbers of benzene nuclei and naphthalene nuclei in one molecule is
refers to a compound that is The novolac type resin of the present invention can be produced, for example, by the method (3) above. (3) above
In the method, it is preferable to use 2 to 10 moles of naphthol, particularly preferably 3 to 6 moles, per 1 mole of dimethylol compound (A). [0021] As the acid catalyst, hydrochloric acid, sulfuric acid, phosphoric acid, p
Although various compounds such as -toluenesulfonic acid and oxalic acid can be used, p-toluenesulfonic acid is preferable in view of smoothness of the reaction and increasing the amount of trinuclear compound (B) produced. The amount of acid catalyst to be used is preferably 0.01 to 10% by weight based on the dimethylol compound (A), but 0.1 to 1% by weight is sufficient. [0022] The reaction temperature is 40 to 85°C, but 50 to 85°C.
Particularly preferred is 80°C. The reaction can be carried out without a solvent or in a solvent such as methanol, ethanol, propanol, butanol, benzene, toluene, or methyl isobutyl ketone. The reaction time is preferably 2 to 15 hours, particularly preferably 4 to 10 hours. [0023] Performing the reaction sufficiently here is effective in preventing polymerization during the subsequent removal of excess unreacted naphthol. After carrying out the reaction in this manner, the acid catalyst is removed by washing with water to make it neutral. [0024] Next, the removal of excess unreacted naphthol, which is an important point of the present invention, is carried out under reduced pressure at 200°C or lower. At this time, if carried out at a temperature exceeding 200°C, the trinuclear compound (
B) causes a high differentiation reaction, which defeats the purpose of lowering the viscosity of the novolac type resin. In addition, steam distillation, which is generally a method for removing phenols and naphthols, causes deterioration of the novolac type resin due to side reactions such as decomposition and recondensation due to oxidation state. Therefore, in the method of the present invention,
It is extremely important to carry out heating distillation at 200° C. or lower under reduced pressure. [0026] According to the method of the present invention, side reactions are suppressed, and the obtained novolac type resin does not undergo the above-mentioned alterations, so it contains at least 30% by weight of the trinuclear compound (B). Become. The novolac type resin of the present invention has a low softening temperature and low viscosity, so it is easy to handle and has excellent workability. Furthermore, the epoxy resin obtained by epoxidizing the novolac type resin of the present invention also has a low viscosity and good workability. Furthermore, cured products using this epoxy resin have excellent moisture resistance and heat resistance. The epoxidation of the novolac type resin of the present invention can be carried out by a conventional method. For example, it can be obtained by reacting the novolac type resin with epichlorohydrin in the presence of a basic compound. The obtained epoxy resin can be cured by a conventional method using a known curing agent such as the novolak type resin of the present invention or a phenol novolak. The novolac type resin of the present invention can also be used as a curing agent for ordinary epoxy resins, and provides a cured product with excellent moisture resistance and heat resistance. [Examples] The present invention will be explained in more detail below with reference to Examples and Application Examples. Example 1 108 g (1 mol) of para-cresol, 60 g (2 mol) of paraformaldehyde, and 100 ml of water were placed in a 1-liter flask equipped with a thermometer, condenser, dropping funnel, and stirrer, and the mixture was heated while blowing nitrogen. Stirred. At room temperature, 80 g of 15% caustic soda aqueous solution (
0.3 mol (as caustic soda) was slowly added dropwise to the solution while being careful not to generate heat so that the liquid temperature did not exceed 50°C. Thereafter, the mixture was heated to 50° C. in a water bath and reacted for 10 hours. After the reaction, add 200 ml of water, cool to room temperature, and gradually neutralize with 10% hydrochloric acid aqueous solution while paying attention to heat generation.
Aqueous hydrochloric acid solution was added until H was 4. Thereafter, the precipitated crystals were filtered and further washed with water. The obtained crystals were dried under reduced pressure (10 m
mHg) was dried at 50°C to obtain white 2,6-dimethylol-4-methylphenol. The yield was 143g. (Yield from para-cresol is 85%) 2
, 168 g of 6-dimethylol-4-methylphenol was placed in a glass container equipped with a thermometer and a stirrer, and further α
- 576 g of naphthol and 10 g of methyl isobutyl ketone
00 ml was added thereto and stirred at room temperature under nitrogen atmosphere. Then, 1 g of p-toluenesulfonic acid (0.6% by weight based on 2,6-dimethylol-4-methylphenol) was gradually added while paying attention to heat generation so that the liquid temperature did not exceed 50°C. After the addition, the mixture was heated to 50°C on an oil bath and reacted for 2 hours, further heated to 70°C and reacted for 7 hours, and then transferred to a separatory funnel and washed with water. After washing with water until the washing water becomes neutral, remove unreacted naphthol from the organic layer using an evaporator under reduced pressure (10 mmHg or less).
The mixture was distilled under reduced pressure and heated at a bath temperature of 195°C. Distillation time required 2 hours. [0035] Through this operation, novolac type resin (A-1
) 372g was obtained. The softening temperature of product (A-1) is 11
The hydroxyl equivalent (g/mol) was 137 at 2°C. Further, the amount of unreacted naphthol in the product (A-1) was found to be 1% by weight or less as a result of gas chromatography analysis. [0036] Furthermore, by GPC analysis, product (A-1)
The content of the trinuclear compound (B) in it is 52% by weight, and the content of compounds with lower molecular weight than the trinuclear compound (B) is 3.5%.
% by weight, and the total content of polynuclear compounds of hepta-nuclear or higher was 15% by weight. The viscosity of the product (A-1) is 25
It was Poise. Example 2 In Example 1, the amount of α-naphthol used was 504 g.
Except for that, 375 g of novolac type resin (A-2) was obtained in the same manner as in Example 1. The product (A-2) had a softening temperature of 118°C and a hydroxyl equivalent (g/mol) of 138. Further, the amount of unreacted naphthol in the product (A-2) was found to be 1% by weight or less as a result of gas chromatography analysis. [0038] Furthermore, by GPC analysis, product (A-2)
The content of the trinuclear compound (B) in it is 45% by weight, and the content of compounds with lower molecular weight than the trinuclear compound (B) is 3.2%.
% by weight, and the total content of polynuclear compounds of heptanucleates or more was 17% by weight. The viscosity of the product (A-2) is 27
It was Poise. Comparative Example 1 In Example 1, after washing with water in a separatory funnel until the washing water becomes neutral, the amount of unreacted naphthol (less than 1% by weight) is reduced to the same amount as in Example 1 by using steam at 150°C. Steam distillation was performed until Steam distillation took 5 hours. (The amount of unreacted naphthol after 2 hours, which was the same operating time as in Example 1, was 3.5% by weight.) In this way, 365 g of product (A-3) was obtained. The softening temperature of the obtained product (A-3) was 135°C,
The hydroxyl equivalent was 143. Moreover, as a result of gas chromatography analysis, the amount of unreacted naphthol in the product (A-3) was 1% by weight or less. Furthermore, according to GPC analysis, the content of the trinuclear compound (B) in the product (A-3) is 25% by weight, and the content of compounds with lower molecular weight than the trinuclear compound (B) is 15% by weight. weight%
, and the total content of polynuclear compounds of heptanucleates or more is 30
% by weight. The viscosity of the product (A-3) was 39 poise. Application Example 1 137 g of the product (A-1) of Example 1 was charged into a reactor equipped with a thermometer, a stirrer, and a vacuum recovery device, and 374 g (3.5 mol) of epichlorohydrin and 68 g of dimethyl sulfoxide were added. was added and dissolved. During this time,
Nitrogen is introduced into the system. After dissolution, while keeping the reaction temperature at 40°C,
40 g (1 mole) of solid caustic soda was slowly added. The addition time required 1 hour. After the addition of caustic soda, the reaction was further carried out at 40°C for 1 hour, and then the reaction temperature was raised to 70°C, and the reaction was further carried out for 1 hour. As a result, the total reaction time was 3 hours. [0044] Next, the bath temperature of the reactor was raised to 130°C, and the pressure was gradually reduced while paying attention to bumping, to expel unreacted epichlorohydrin, dimethyl sulfoxide, and produced water all at once. The final degree of vacuum is 5 mmHg,
This took two hours. Then, 500 m of methyl isobutyl ketone
1, dissolve the resin, and add 20% caustic soda aqueous solution 2.
0 g was added, and the reaction was carried out at a reaction temperature of 70° C. for 2 hours. After the reaction was completed, washing with water was repeated using a separatory funnel to return the aqueous phase to neutrality. The methyl isobutyl ketone phase was then heated under reduced pressure to remove the methyl isobutyl ketone. As a result, 175 g of a pale yellow solid (B-1), which is an epoxy resin, was obtained. The softening temperature of the product (B-1) is 75°C, and the epoxy equivalent (g/mol) is 21
2. Viscosity: 10 poise, free chlorine amount: 1 ppm or less, hydrolyzable chlorine amount: 230 ppm, total chlorine amount: 510 ppm
m, the chloride ion concentration in the extracted water by PCT is 3pp
It was m. Application Example 2 The same operation as in Application Example 1 was carried out except that 139 g of the product (A-2) obtained in Example 2 was used instead of the product (A-1), and the epoxy resin was The product (B-2) 17
2g was obtained. Application Example 3 The product (A-1) obtained in Comparative Example 1 was replaced with the product (A-1).
-3) Using 143g, 68g of dimethyl sulfoxide
The same operation as in Application Example 1 was carried out except that 68 g of methanol was used instead of the epoxy resin (B-
3) 150g was obtained. The properties of the products (B-1) to (B-3) are shown in Table 1. In the Examples, Comparative Examples and Application Examples, the amount of free chlorine, the amount of hydrolyzable chlorine, the viscosity, the softening temperature,
Total chlorine content, PCT (pressure cooker test)
The amount of chlorine was measured by GPC analysis as follows. (Amount of free chlorine) Approximately 10 g of the sample (epoxy resin) was accurately weighed into a 200 ml beaker, dissolved in 100 ml of acetone, and then 2 ml of distilled water and 1 ml of glacial acetic acid were added to prepare a silver nitrate aqueous solution. The amount was determined by potentiometric titration. (Amount of Hydrolyzable Chlorine) Approximately 0.5 g of a sample (epoxy resin) is accurately weighed into a 100 ml flask with a stopper, and dissolved in 30 ml of dioxane. After dissolution, 5 ml of 1N-KOH ethanol solution is added, and the mixture is boiled and refluxed for 30 minutes. Thereafter, this solution was completely transferred to a 200 ml beaker, 100 ml of an 80% aqueous acetone solution was added thereto, 2 ml of concentrated nitric acid was further added, and the amount was determined by potentiometric titration with an aqueous silver nitrate solution. (Viscosity) The viscosity at 150°C was measured using an ICI viscometer (cone plate type). (Softening temperature) Measured by JIS K2425 ring and ball method. (Total chlorine amount) Approximately 1 g of the sample (epoxy resin) was accurately weighed into a 100 ml flask with a stopper, and n-butylcarbitol 2
Add 5ml and heat to dissolve. After dissolving, 1N-
Add 25 ml of KOH propylene glycol solution and heat to reflux for 10 minutes. Thereafter, this solution was completely transferred to a 200 ml beaker, 50 ml of glacial acetic acid was added, and the amount was determined by potentiometric titration with an aqueous silver nitrate solution. (Amount of chlorine according to PCT) Add 50 g of ion exchange water to 5 g of epoxy resin,
The chloride ion concentration in the extracted water was determined by ion chromatography when the extract was kept at ℃ for 20 hours. (GPC analysis) GPC device: Shimadzu Corporation (column: TSK-G-3000XL (1 piece) + TSK
-G-2000XL (2 bottles) Solvent: Tetrahydrofuran 1ml/min
Detection: UV (254 nm) [0058] Application Examples 4 to 6 Phenol novolac (manufactured by Nippon Kayaku Co., Ltd., softening temperature 85°C, hydroxyl group equivalent (g/mol)
105) and the products (B-1) obtained in Application Examples 1 to 3
(B-3) and 2-methylimidazole were blended to obtain a composition. [0059] This composition was roll-kneaded at 70 to 80°C for 15 minutes, cooled, crushed, and tableted. After molding using a transfer molding machine, it was precured at 160°C for 2 hours, and then at 180°C for 8 hours. Post-curing was performed to obtain a cured product (test piece). The glass transition temperature (Tg), heat distortion temperature (HDT), and water absorption of this cured product were measured under the following conditions. Glass transition temperature thermomechanical measuring device (TMA): Shinku Riko Co., Ltd. T
M-7000 Heating rate: 2℃/min Heat distortion temperature Conditions specified in JIS K7207 0061
】Water absorption test piece diameter 50
mm (cured product) thickness
3mm disc condition
Weight increase (% by weight) after boiling in water at 100°C for 50 hours The evaluation results of the cured product are shown in Table 2. Effects of the Invention: The novolak resin of the present invention has low viscosity and excellent workability, and the epoxy resin obtained from it also has low viscosity and excellent workability, and furthermore, the cured product of this epoxy resin is moisture resistant. Excellent strength and heat resistance. According to the method of the present invention, the novolak resin can be easily obtained.

Claims (3)

[Claims] Claim 1: A dimethylol compound represented by the formula (A) (wherein R represents an alkyl group having 1 to 4 carbon atoms) and naphthol, which is obtained by reacting a dimethylol compound represented by the formula (B) (wherein R represents an alkyl group having 1 to 4 carbon atoms) has the same meaning as above), and the content of a compound having a lower molecular weight than the trinuclear compound is 10% by weight or less. 2. The novolak type resin according to claim 1, wherein the total content of polynuclear compounds of hepta-nuclear or higher is 25% by weight or less. 3. The dimethylol compound according to claim 1 (
A) and naphthol are reacted in the presence of an acid catalyst at a temperature of 40 to 85°C, and excess naphthol in the reaction mixture is removed by heat distillation at a temperature of 200°C or less under reduced pressure. A method for producing a novolac type resin according to claim 1 or claim 2.