JP2637623B2 - Method for producing high-ortho novolak resin - Google Patents

Description

The present invention relates to a method for producing a high-ortho novolak resin. More specifically, the present invention relates to a method for producing a high-ortho novolac resin obtained by subjecting a phenol and an aldehyde to a contact reaction under acidic conditions at a controlled temperature of 110 ° C. or higher.

[Conventional technology]

Originally, high-ortho novolak resins are fast-curing resins, so they are widely used as resins for phenolic resin molding materials, which require rapid curing cycles, as well as base resins and binding resins for various organic and inorganic substances. Have been. Conventionally, high orthonovolak resins used for such applications are manganese, zinc, calcium,
Using a divalent metal carboxylate such as magnesium or an organic acid salt such as a naphthenate as a catalyst, and adjusting the pH to 4.0 to 6.0.
In a reaction system adjusted to slightly acidic, phenols and aldehydes are refluxed at a temperature of about 100 ° C., and then heated to remove water and free monomers. However, since the divalent metal compound remains as an impurity in the high-ortho novolak resin obtained by this production method, the curability is superior to that of the random novolak resin obtained by using a normal acidic catalyst. However, the cured product had serious defects such as inferior properties such as heat resistance, water resistance, and electrical insulation.

[Problems to be solved by the invention]

The present inventor has developed a high-ortho novolak resin which does not contain a divalent metal compound remaining as an impurity in a conventional high-ortho novolak resin, and has excellent properties such as fast curing property, heat resistance, water resistance, and electrical insulation. As a result of intensive studies on the production method of novolak resin, a mixture of phenols and a catalyst other than a divalent metal salt was uniformly mixed, and the mixture was adjusted to a pH of 2.5 or less to a temperature of 110 ° C or more. It has been found that it is extremely effective to make the mixed solution contact with aldehydes while controlling, and the inventors have completed various studies based on this finding and completed the present invention. It is.

The purpose is to quickly cure without containing the divalent metal compound remaining as an impurity in the conventional high ortho novolak resin, and the cured product is heat resistant, water resistant, and electrically insulating. An object of the present invention is to provide a method for producing a high-ortho novolak resin having excellent properties such as the following.

[Means for solving the problem]

The present invention relates to a process for producing a novolak resin using phenols, aldehydes and a catalyst as essential components, by mixing a catalyst with phenols and adjusting the mixture to a pH of 2.5 or less, at a temperature of 110 ° C or higher. A method for producing a high-ortho novolak resin, comprising a step of gradually adding an aldehyde to the mixed solution and controlling a contact reaction while controlling the temperature.

The pH of the mixed solution obtained by mixing the phenol with the catalyst is 2.5 or less, preferably 1.5 or less, more preferably 1.0 or less. Here, the pH is a measured value at 25 ° C. of a solution obtained by dissolving a predetermined catalyst in 100 parts by weight of phenols and further adding and mixing 10 parts by weight of pure water.

Next, the temperature at which the aldehyde is brought into contact with the mixed solution is 110 ° C. or higher, but the lower limit is preferably 120 ° C. and the upper limit is a temperature lower than the boiling point of the phenol used by 15 ° C. The contact reaction can be carried out at a temperature higher than the boiling point of phenols at normal pressure by pressurizing the reaction system.

The high-ortho novolak resin obtained by the method for producing a high-orno novolak resin of the present invention has a different degree of high ortho-ortholation depending on the temperature at which an aldehyde is brought into contact with the mixed solution. Since the higher the contact reaction temperature is, the higher the degree of high ortho-formation becomes, it is necessary to select a contact reaction temperature suitable for a desired degree of high ortho-formation. That is, the contact reaction temperature needs to be 130 ° C. or higher to obtain a novolak resin having a high degree of high ortholation, and conversely, 110 to 130 ° C. to obtain a novolak resin having a relatively low degree of high ortholation.

Next, when the pH exceeds 2.5, the reactivity between the phenols and the aldehydes is low, and the condensation reaction requires a long time, which is not preferable as an industrial production method and is not practical. On the other hand, when the contact reaction temperature is lower than 110 ° C., the degree of high ortho-formation is small, so that there are few manifestations of remarkable features such as rapid curability.

Here, Haioruso degree with pyridine solvent ¹ H-
Represented by the ratio of ortho bonds / para bonds (O / P ratio) determined from the peak area ratio of each of the ortho / ortho, ortho / para and para / para bonds by NMR <P. Yoshikawa, et al .: Makr
omol. Chem., 131 , 273 (1970)>.

The O / P ratio for a high-ortho novolak resin to have fast-curing characteristics is 1.0 or more for a phenol novolak resin and 1.1 or more for a meta-cresol novolak resin.

The method for producing a high-ortho novolak resin of the present invention includes:
As phenols, one or more selected from phenol and meta-cresol having a substituent at the meta-position, 3,5-xyler, 3-ethylphenol and the like can be used. It also includes the combined use of phenolic compounds such as orthocresol and paracresol.

As the aldehyde, one or more selected from formaldehyde, paraformaldehyde, trioxane, acetaldehyde, benzaldehyde and the like can be used, but formaldehyde and paraformaldehyde are preferred.

The contact reaction method of aldehydes is such that paraformaldehyde, which is a part of the aldehydes, is used in an amount within a range where the contact reaction temperature set at 110 ° C. or more can be controlled,
Charge with phenols and catalyst in advance,
Thereafter, the remaining temperature of the aldehyde is gradually added while maintaining the same temperature to effect a contact reaction, which is also included in the present invention.

The shape of the aldehydes is preferably liquid or gaseous from the viewpoint of easy addition and easy control of the generated reaction heat. In addition, it is necessary that the position in the reactor when the aldehydes are actually brought into contact is as low as possible in order to cause an efficient contact reaction. Phenols (P) and aldehydes (F)
Is different depending on the characteristics required for the produced novolak resin, but is generally in the range of 0.50 to 0.90.

As the catalyst, an organic acid and / or an inorganic acid can be used,
As the organic acid, oxalic acid, malonic acid, formic acid, benzoic acid, paratoluenesulfonic acid and the like, and as the inorganic acid, one or more selected from sulfuric acid, hydrochloric acid, phosphoric acid and the like,
Preferred are catalysts such as oxalic acid, malonic acid and formic acid, in which neutralized salts and the like do not remain as impurities in the novolak resin.

In the method for producing a high orthonovolak resin of the present invention, when an aldehyde is brought into contact with a mixture of a phenol and a catalyst, a non-polar solvent can be added to the mixture as an azeotropic solvent. As a type of the nonpolar solvent, the boiling point of one or more mixed catalysts under normal pressure is 110 to 160 ° C. and a solvent insoluble in water, for example, toluene, xylene, mesitylene, ethylbenzene, One or more selected from aromatic hydrocarbons such as cumene and paracymene, aliphatic hydrocarbons such as nonane, decane and paramethane, and esters such as 2-ethylbutyl acetate and methoxybutyl acetate can be used. . The amount of the solvent to be used is not particularly limited, but is preferably 3 to 30% by weight, more preferably 5 to 20% by weight, based on the phenol.

The production mode of the high-ortho novolak resin of the present invention will be described in detail. The production process comprises a first stage reflux dehydration reaction and a second stage vacuum dehydration reaction. The first-stage reflux dehydration reaction is the first
Phenols were charged into a reactor equipped with a reaction vessel 1, a stirrer 2, a thermometer 3, a heat exchanger 4 and a water separator 5 as shown in the figure, and a catalyst was further mixed to adjust the pH of the mixture to 2.5. The temperature is adjusted so as to be as follows, and if necessary, a solvent is added to raise the temperature to a set temperature of 110 ° C. or more. After that, while maintaining the same temperature, the separated water is discharged out of the reaction vessel 1,
When a solvent is used, the aldehydes in the aldehyde tank 6 are gradually added over 2 to 10 hours while returning the solvent into the reaction vessel 1, and after the addition, the same operation is repeated. The reflux dehydration reaction is performed continuously for 10 hours. Then, the process proceeds to the subsequent step of dehydration under reduced pressure, and while maintaining the reaction solution at a vacuum of 200 Torr or less and a temperature of 280 ° C or less, the residual water and free phenols are removed by a heating method or a steam distillation method. When a solvent is used, the solvent is discharged out of the reaction vessel 1 to obtain a high-ortho novolak resin.
If necessary, a phenolic monomer is added later to adjust the monomer content.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples. In addition,
“Parts” and “%” described in Examples and Comparative Examples indicate “parts by weight” and “% by weight”.

Example 1 1000 parts of phenol and 5 parts of oxalic acid were charged into a reactor consisting of a reaction vessel 1, a stirrer 2, a thermometer 3, a heat exchanger 4 and a water separator 5, and the pH of the mixture was measured. Thereafter, the mixed solution A obtained by adding 50 parts of toluene to the mixed solution was subjected to a contact reaction temperature of 115.
The temperature was raised to ± 2 ° C. While maintaining the mixed solution A at the same temperature, the separated water was drained out of the reaction vessel 1, and the solvent was returned to the reaction vessel 1 while the 37% contained in the aldehyde tank 6.
675 parts of an aqueous formaldehyde solution was added to the mixture A over 3.0 hours, and after the addition, the mixture was kept at the same temperature for 1.0 hour to perform a reflux dehydration reaction. Subsequently, the process proceeds to the subsequent step of dehydration under reduced pressure.
℃, then raise to 60 Torr at the same temperature
A high ortho novolak resin was obtained by removing residual moisture, solvent and free monomer over 1.0 hour. The measurement results of the pH of the mixed solution and the general characteristics and cured product characteristics of the resulting high-ortho novolak resin were as shown in Tables 1 and 3.

Examples 2, 4, 6 A dehydration reaction using the same reactor as in Example 1 but without the water separator 5 is performed without using a solvent, and therefore, without returning the solvent into the reactor. Except for the above, a hyortho novolak resin was obtained by the same procedure as in Example 1 and the reaction conditions shown in Table 1. PH of the mixture
The measurement results of the general properties and the properties of the cured product of the resulting high ortho novolak resin were as shown in Tables 1 and 3.

Examples 3, 5, and 7 Using a reaction apparatus of the same type as in Example 1, and using the same procedure as in Example 1 and the reaction conditions shown in Table 1, a high-ortho novolak resin was obtained. The measurement results of the pH of the mixed solution and the general characteristics and cured product characteristics of the resulting high-ortho novolak resin were as shown in Tables 1 and 3.

Examples 8 and 10 Using a reaction apparatus of the same type as in Example 1 and using metacresol as a phenol, the same procedure as in Example 1 and the reaction conditions shown in Table 2 were used to obtain a high orthonovolak resin. I got Table 2 shows the measurement results of the pH of the mixed solution and the general characteristics of the produced high ortho novolak resin.

Example 9 Using a reaction apparatus of the same type as in Example 2 and using metacresol as a phenol, a high-ortho novolak resin was obtained according to the same procedure as in Example 2 and the reaction conditions shown in Table 2. Was. Table 2 shows the measurement results of the pH of the mixed solution and the general characteristics of the produced high ortho novolak resin.

Examples 11 and 12 Using the same type of reactor as in Example 1 and using metacresol and another one as phenols, the following Example 1 was used.
A hyortho novolak resin was obtained according to the same procedure as in the above case and the reaction conditions shown in Table 2. Table 2 shows the measurement results of the pH of the mixed solution and the general characteristics of the produced high ortho novolak resin.

Comparative Examples 1 and 4 Novolaks were obtained using the same type of reactor as in Example 1 according to the same procedure as in Example 1 and the reaction conditions shown in Table 1 or Table 2. Table 1 or 2 shows the measurement results of the pH of the mixture and the general characteristics of the produced novolak.
The cured product characteristics of the table and Comparative Example 1 are as shown in Table 3.

Comparative Examples 2, 5, and 6 Using the same type of reactor as in Example 2, a novolak was obtained according to the same procedure as in Example 2 and the reaction conditions shown in Table 1 or Table 2. Table 1 or 2 shows the measurement results of the pH of the mixture and the general characteristics of the produced novolak.
The cured product characteristics of the table and Comparative Example 2 were as shown in Table 3.

Comparative Examples 3 and 7 As shown in Table 1 or 2, 1000 parts of phenols, a predetermined amount of 37% aqueous formaldehyde solution and 6.0 parts of zinc acetate were charged into a reactor of the same type as in Example 2 to adjust the pH to 5.5. After that, a reflux reaction was performed at 100 ± 2 ° C. for 2 hours.
Thereafter, the pH was reduced to 1.5 using oxalic acid, and the reaction solution was dehydrated at elevated temperature under normal pressure until the liquid temperature reached 130 ° C., and further heated at a reduced pressure of 60 Torr to a liquid temperature of 160. C. and kept at the same temperature for 1 hour to remove residual moisture and free monomers, thereby obtaining a high ortho-type novolak. The measurement results of the general characteristics of the resulting high ortho-type novolak are shown in Table 1 or Table 2. The cured product characteristics of Comparative Example 3 are as shown in Table 3.

〔The invention's effect〕

According to the method for producing a high-ortho novolak resin according to the present invention, manganese, zinc, casium, an organic acid salt of a divalent metal such as magnesium is used as a catalyst, and the pH is adjusted to 4.
Fast curing without containing divalent metal compounds remaining as impurities in conventional high ortho novolak resins obtained by reacting phenols and aldehydes in a reaction system adjusted to weak acidity of 0 to 6.0 It is. In addition, the cured product has excellent properties such as heat resistance, water resistance, and electrical insulation as compared with conventional high ortho novolak resins, and therefore, a high ortho novolak resin having excellent properties is industrially manufactured. It is suitable as a method. The high-ortho novolak resin produced by this method is used for molding materials, grindstones, friction materials, electrical insulation, and felts, which require the development of novolak resins with excellent properties such as fast curing, heat resistance, and water resistance. It is extremely effective when used for bonding of organic and inorganic substances, or for photoresists and PS plates where high-purity high-ortho-type cresol-based novolak resins with excellent resist properties and no impurities are required. Expected to be.

<Method for measuring general properties> 1. Melting point: according to JIS K 6909 2. Free monomer amount: gas chromatography 3. Hot plate gelation time: according to JIS K 6909.

Hexamine content: 15 phr, hot plate temperature: 150 ° C 4. High ortholation degree: NMR method, O / P ratio <Measurement method of cured product characteristics> 1. Acetone extraction ratio Preparation of sample: Powdered resin is finely ground together with 15 phr of hexamine, and is heat-molded into a tablet at 150 ° C / 1Hr and cured. The cured resin is pulverized and a sample passing through 60 mesh is used.

Extraction device and extraction time: 6Hr treatment by Soxhlet extractor.

2. Normal bending strength (A) Preparation of powdered resin: Finely pulverized with 15 phr of hexamine to obtain powdered resin.

Preparation of test piece Formulation: powder resin: alumina (# 400) = 40:60 (Vol.%)
Dry blend.

Dimensions: 20 × 120 × 10mm Curing: 160 ° C. × 20 minutes Post-curing: 180 ° C. × 5Hr Apparent specific gravity: 2.55 ± 0.02 Measurement conditions: Using a Tensilon type bending strength tester, the span is 100mm, the load speed is 20 mm / min.

3. Hot bending strength (B) Preparation of powder resin and preparation of test specimen: Same as normal bending strength.

Measurement conditions: The prepared test piece is heat-treated in a furnace at 250 ° C. for 20 minutes, and the test piece immediately after the heat treatment is measured under the same conditions as in the case of normal bending strength.

4. Hot strength retention (B / A) Calculated from (hot bending strength / normal bending strength) x 100.

5. Wet bending strength (C) Preparation of powder resin and preparation of test specimen: Same as normal bending strength.

Measurement conditions: After polishing the surface of the prepared test piece with sandpaper, immersion treatment was performed in hot pressurized water at 110 ° C. for 2 hours. The test specimen after immersion treatment was measured under the same conditions as for normal bending strength.

6. Wet strength retention (C / A) Calculated from (wet bending strength / normal bending strength) x 100.

In the resins obtained in Examples 1 to 12, the higher the contact reaction temperature of phenols and aldehydes, the higher the degree of high Olsonization (O / P ratio). The resins of Examples 1 to 12 are Comparative Examples 1 to
As compared with the resin No. 8, the degree of high ortho-formation was high, and the hot plate gelation time was short, indicating that the resin was fast-curing. In addition, the resins of Examples 1 to 7 have a lower acetone extraction rate and better curability than the resin obtained in Comparative Example 3,
The fact that the hot bending strength and the hot strength retention are large and excellent in heat resistance indicate that the wet bending strength and the wet strength retention are large and excellent in moisture resistance.

[Brief description of the drawings]

FIG. 1 is a schematic view of a reaction apparatus for producing a high-ortho novolak resin in the method for producing a high-ortho novolak resin of the present invention. 1. Reactor 2. Stirrer 3. Thermometer 4. Heat exchanger 5. Water separator 6. Aldehyde tank

Claims (1)

(57) [Claims] In a process for producing a novolak resin using phenols, aldehydes and a catalyst as essential components, a mixed solution prepared by mixing a phenol with a catalyst to adjust the pH to 2.5 or less is used. A process for contacting aldehydes with the mixture while controlling the temperature of the mixture to 110 ° C. or higher while discharging water out of the reaction system. .