JP5254598B2 - Method for producing high molecular weight high ortho novolac resin - Google Patents

Description

  The present invention relates to a method for producing unreacted phenols and a high molecular weight high ortho novolac resin having a low binuclear content.

The novolac type phenol resin is generally produced by addition condensation of phenols and aldehydes in the presence of an acidic catalyst. When a strong acid such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, p-toluenesulfonic acid, or oxalic acid is used as the acidic catalyst, the phenols are ortho-para-position, para-position, and ortho-position via a methylene bond. A so-called random novolak resin in which the bonded ones are mixed is obtained.
On the other hand, high ortho novolac resin is a resin containing many phenols bonded at ortho positions through a methylene bond. Examples of the catalyst include acetates of divalent metals (Ca, Mg, Zn, etc.). It can be obtained by reacting with a weak acid.
Such a high-ortho novolak resin has few volatile components even at high temperatures. For example, when it is used as a curing agent for an epoxy resin, a molded product having excellent heat resistance can be obtained. Further, since the ratio of ortho-ortho bond is high, the molecule becomes linear, and as a result, the toughness of the molded product is improved and the pot life of the epoxy compound is increased.
However, when synthesizing a high ortho novolac resin, the reaction system has a low acidic pH range, so the reaction rate is slower than that of a random novolac resin, and there are many low molecular weight components such as unreacted phenols and dinuclear compounds. It becomes resin containing.
When such unreacted substances are contained in a large amount, when the product is used at the site of use, the unreacted substances sublimate and adhere to the production equipment and become contaminated. Will be reduced.

In order to solve this problem, various methods have been conventionally proposed.
For example, Patent Document 1 discloses a method of distilling off unreacted phenols and dinuclear substances by steam distillation.
However, in this method, in order to remove the binuclear body by steam distillation, it is necessary to perform distillation for a long time at a high temperature of at least 220 ° C. or more. Further, according to Patent Document 1, after removing unreacted phenols and dinuclear bodies to increase the molecular weight of the novolak resin, aldehydes and oxalic acid are added and reacted again as a secondary reaction. Since the reaction of the phenols and aldehydes in the reaction is carried out in the presence of a strong acid, and the para position of the phenols present in the system at this stage is vacant, the methylene bond formed in the secondary reaction is in the para position. Although most of them are ortho-or para-positions and a high molecular weight novolak resin is obtained, the bond ratio between ortho-positions is lower than that of a general high ortho novolac resin.
In Patent Document 2, first, phenols and aldehydes are reacted as a primary reaction in the absence of a catalyst at a reaction temperature of 180 to 280 ° C. to synthesize a high ortho novolak resin, and then as secondary reactions, aldehydes and organics are synthesized. A method for obtaining a high molecular weight novolak resin by performing a reaction by adding phosphonic acid is shown.
However, since the organic phosphonic acid has a higher acidity than a weakly acidic catalyst such as a divalent metal acetate known as a synthesis catalyst for a high ortho novolac resin, the bond between the ortho positions of the resulting novolak resin is obtained. The ratio is lower than that of a general high ortho novolac resin.
Patent Document 3 discloses a method for producing a novolak resin in which paraformaldehyde is continuously supplied at a temperature of 100 to 150 ° C. in the presence of a phenol and a divalent metal salt, and the reaction is performed while removing water. .
However, although the method described in Patent Document 3 has an advantage that the reaction time is shortened, it is difficult to produce a resin having a low molecular weight or a low molecular weight component because the solid concentration in the system is high. Therefore, a high molecular weight high ortho novolac resin having a low content of unreacted phenols and dinuclear bodies cannot be obtained.

Japanese Patent Application Laid-Open No. 11-246643 JP 2003-212943 A Japanese Patent Laid-Open No. 2001-247639

  The present invention has been intensively studied in order to solve the conventional problems as described above, and has a low content of unreacted phenols and dinuclear compounds, and has a high molecular weight and a large number of ortho-ortho bonds. It aims at providing the high ortho novolak resin containing.

Such an object is achieved by the present invention described in the following 1-7. That is, the present invention
1. A method for producing a high molecular weight high ortho novolac resin, characterized by removing hydration in the system while sequentially adding and reacting aldehydes in the presence of phenols, a weakly acidic catalyst and an organic solvent,
2. The method for producing a high molecular weight high ortho novolak resin according to claim 1, wherein an organic solvent having a boiling point in the range of 80 to 180 ° C is used so that the reaction temperature is 130 to 180 ° C.
3. A high-molecular-weight high-ortho according to claim 1 or 2, further comprising a step of removing unreacted phenols by distillation under reduced pressure, wherein the distillation temperature in the removal step is 180 ° C or lower and the degree of vacuum is 6666 Paabs (50mmHgabs) or lower. Production method of novolac resin,
4). The method for producing a high molecular weight high-ortho novolak resin according to any one of claims 1 to 3, wherein the high-molecular weight high-ortho novolak resin has an ortho-ortho bond ratio with respect to all methylene bonds of 75% or more.
Is to provide.

By the method for producing a high molecular weight high ortho novolak resin of the present invention, a high ortho novolac resin having a low content of unreacted phenols and dinuclear compounds in the resin and having a high molecular weight and a large number of ortho-ortho bonds is provided. Can do.
As a result, the high-ortho novolak resin of the present invention has few volatile components even at high temperatures. For example, when it is used as a curing agent for epoxy resins, a molded product having excellent heat resistance can be obtained. Further, since the ratio of ortho-ortho bond is high, the molecule becomes linear, and as a result, the toughness of the molded product is improved and the pot life of the epoxy compound is increased.

The present invention will be described in detail below.
The high ortho novolak resin in the present invention is produced by reacting phenols and aldehydes under a weakly acidic catalyst.
The phenols used in the method of the present invention may be those used for the production of general phenol resins, such as phenol, cresol, ethylphenol, xylenol, butylphenol, octylphenol, nonylphenol, phenylphenol, cyclohexylphenol. , Trimethylphenol, bisphenol A, catechol, resorcinol, hydroquinone, naphthol, pyrogallol, vanillin, xylenol and the like can be used alone or in admixture of two or more. Of these, phenol and cresols are practically preferable.

On the other hand, as aldehydes to be reacted with phenols, any aldehydes that can be used for the production of phenol resins can be used. For example, formaldehyde, acetaldehyde, benzaldehyde, hydroxybenzaldehyde, paraformaldehyde, propylaldehyde, butyraldehyde, isovaleraldehyde, hexylaldehyde, glyoxal, crotonaldehyde, glutaraldehyde, etc. can be used alone or in combination of two or more. . Of these, formaldehyde is practically preferable.
The aldehydes are used in an amount of 0.6 to 1.5 mol, preferably 0.7 to 1.2 mol, based on 1 mol of the total amount of phenols. If the amount of aldehydes used is less than 0.6 moles, only low molecular weight resins can be obtained. On the other hand, if the amount of aldehydes is more than 1.5 moles, gelation may occur, which is preferable. Absent.
Examples of the sequential addition means of aldehydes include a high-pressure pump such as a known plunger pump and a diaphragm pump, a slurry pump such as a rotary volume type uniaxial eccentric screw pump, and a tube pump.

In the case of the present invention, the type of catalyst used in the above reaction is important for forming an ortho-ortho bond of phenols. In order to form an ortho-ortho bond, it is necessary to make the reaction system weakly acidic. From this viewpoint, catalysts suitable for the present invention include acetates of divalent metals (Ca, Mg, Zn, etc.), boric acid. And weakly acidic catalysts such as borates of divalent metals (Ca, Mg, Zn, etc.), but zinc acetate is practically preferred.
These weakly acidic catalysts can be used alone or in admixture of two or more.
The amount of such weakly acidic catalyst is 0.1 to 20 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, based on 100 parts by weight of phenols. It is desirable to use it.
In addition, there are strong acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, paratoluenesulfonic acid, oxalic acid, etc. as catalysts used in the production of ordinary novolak resins. When these are used, the pH of the reaction system is lowered. As a result, many methylene bonds other than the ortho-ortho bond are formed. In addition, since the high molecular weight is advanced without sufficiently reducing the low molecular weight component, the target resin cannot be obtained.
Therefore, in the method of the present invention, it is necessary not to use such strong acids at all.

In the method of the present invention, it is preferable to adjust the type and amount of the organic solvent so that the temperature of the reaction system is in the range of 130 to 180 ° C.
In the method of the present invention, phenols and aldehydes can be reacted with phenols in the presence of a weakly acidic catalyst and an organic solvent by sequentially adding aldehydes and removing moisture in the system. Importantly, it is preferable that the reaction temperature is in the range of 130 to 180 ° C. at this time because the reaction proceeds rapidly and unreacted aldehydes and methylol groups hardly remain.
For this reason, the organic solvent used as the reaction solvent preferably has a boiling point in the range of 80 to 180 ° C. If the boiling point of the solvent is less than 80 ° C., it is not preferable for the reaction temperature to be 130 ° C. or higher because the amount of use is limited to a small amount. On the other hand, if the boiling point exceeds 180 ° C., the organic solvent is finally used. Is not preferable because it may remain in the resin.
Examples of the organic solvent having a boiling point of 80 to 180 ° C include alcohols such as propyl alcohol and butanol, glycol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, ketones such as methyl isobutyl ketone and cyclohexanone, Esters such as butyl acetate, ethylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether acetate, ethers such as 1,4-dioxane, and the like can be used alone or in combination of two or more.
The amount used is generally about 10 to 100 parts by weight per 100 parts by weight of phenols.
In the method of the present invention, the organic solvent is essential for efficiently reacting phenols and aldehydes. As the reaction proceeds and the molecular weight of the novolak resin increases and the viscosity in the reaction system increases, the aldehydes that are sequentially added become difficult to mix with the resin. However, by using an organic solvent, the viscosity in the system is kept low, and as a result, the reaction between the aldehydes and the novolak resin proceeds efficiently. Of course, when a decrease in the organic solvent due to distillation or an increase in the viscosity of the system due to an increase in the molecular weight of the resin is observed, an organic solvent may be added as appropriate.
When organic solvents are not used, the concentration of aldehydes added sequentially increases locally, resulting in spot gels or being discharged out of the system without reacting with aldehydes, It is not preferable.

Further, condensed water is generated with the progress of the reaction between phenols and aldehydes. If this condensed water remains in the reaction system as it is, the phenols and aldehydes cannot be efficiently subjected to an addition condensation reaction. Therefore, in the method of the present invention, the water in the produced reaction solution is removed by making an azeotropic mixture with the organic solvent and distilling under the reaction temperature condition. In order to remove the water thus generated, the organic solvent exhibits an important effect.
The azeotropic mixture discharged out of the system is separated from moisture by a known means, and then the organic solvent may be refluxed into the reaction system.
There is no restriction | limiting in particular in the reaction time in this invention method, What is necessary is just to adjust suitably with the quantity of aldehydes and a catalyst, and reaction temperature.

Thus, after the addition of aldehydes is completed, the reaction is usually continued for about 0.5 to 2 hours. Thereafter, the condensed water may be further removed by dehydration, and the remaining catalyst may be removed by washing with water if necessary.
Since the unreacted phenols remain in the reaction solution thus obtained, the process proceeds to a process for removing unreacted phenol.
Examples of means for removing unreacted phenol include known means such as vacuum distillation and steam distillation.
When removing unreacted phenols by performing vacuum distillation or steam distillation, the distillation temperature is preferably 180 ° C. or lower. Although unreacted phenols can be removed even at 180 ° C. or higher, the removal efficiency is hardly changed, and the energy cost is increased, which is not preferable. In the production method of the present invention, since the amount of the binuclear substance has already been sufficiently reduced before the step of removing the unreacted phenols, it is sufficient that there are conditions sufficient to remove the unreacted phenols. Temperatures above ℃ are not necessary.
In order to mainly remove unreacted phenols efficiently, it is desirable that the temperature is 180 ° C. or less and the vacuum is 6666 Paabs (50 mmHgabs) or less. As a result, in the present invention, the component of a binuclear body or less can be reduced to about 8% or less.

As described above, in the method of the present invention, a high-ortho novolac resin having a high molecular weight and containing a large number of ortho-ortho bonds is produced.
The ortho novolak resin has a weight average molecular weight of 10,000 or more, preferably 30,000 to 100,000, more preferably about 40,000 to 70,000.
Further, an ortho-novolak resin having an ortho-ortho bond ratio of 75% or more is obtained.

  As described above, the high molecular weight high ortho novolak resin obtained by the method of the present invention has few volatile components even at high temperatures. For example, when used as a curing agent for an epoxy resin, a molded product having excellent heat resistance can be obtained. Moreover, since the ratio of the ortho-ortho bond is high, the molecule becomes linear, and as a result, excellent effects such as improved toughness of the molded product and longer pot life of the epoxy compound are obtained.

The method for synthesizing a high molecular weight high ortho novolak resin by the method of the present invention will be described more specifically below, but the method of the present invention is not limited to the following synthesis examples. Here, parts and% are based on mass.
The analysis method of the resin used in this example is as follows.
(1) GPC
The column configuration was KF-804 + KF-804 manufactured by Showa Denko KK, and tetrahydrofuran was used as a solvent, and measurement was performed at a flow rate of 1 ml / min.
The molecular weight was calculated in terms of polystyrene, and the content was calculated as a percentage of the total peak area.
(2) Ortho-ortho coupling ratio
^It calculated from the ratio of the ortho-ortho, ortho-para, para-para methylene bond by < ¹³ > C-NMR spectrum.
Ortho-ortho bond ratio (%) = (ortho-ortho bond / total methylene bond) × 100
(3) Softening point It measured with the temperature increase rate of 2.5 degree-C / min using the vapor-phase softening point measuring apparatus EX-719PD by Elex Scientific.
(4) Loss on heating It was measured at 10 ° C./min in the air atmosphere using SSC / 5200 manufactured by SII.

Example 1
A flask equipped with a condenser and a stirrer was charged with 100 parts of phenol, 0.5 part of zinc acetate and 20 parts of methyl isobutyl ketone, the internal temperature was 150 ° C., and 69 parts of 37% formalin was added dropwise over 3 hours. During the dropwise addition, methyl isobutyl ketone and water azeotrope, but water was removed and methyl isobutyl ketone was refluxed.
After completion of the dropwise addition, the reaction was further continued at the same temperature for 1 hour, followed by washing with water several times to remove the catalyst.
Subsequently, steam distillation was performed under reduced pressure of 170 ° C. and 50 mmHgab to remove unreacted phenol. As a result, a high molecular weight high ortho novolac resin having a low molecular weight component content of 2.9% or less and a weight average molecular weight of 49000 was obtained.

Example 2
A flask equipped with a condenser and a stirrer was charged with 100 parts of phenol, 0.5 part of zinc acetate and 20 parts of propylene glycol monomethyl ether acetate, the internal temperature was 150 ° C., and 69 parts of 37% formalin was added dropwise over 3 hours. did. All the azeotropic mixture distilled during the dropping was discharged out of the system. After completion of the dropping, the reaction was aged at the same temperature for 1 hour, and then washed with water several times to remove the catalyst. Next, steam distillation was performed under reduced pressure at 170 ° C. and 6666 Paabs (50 mmHgabs) to remove unreacted phenol. As a result, a high molecular weight high ortho novolac resin having a low molecular weight component content of less than 2 nuclei of 4.5% and a weight average molecular weight of 50200 was obtained.

Example 3
The procedure was the same as in Synthesis Example 1 except that 100 parts of metacresol and 41 parts of 37% formalin were used as phenols. As a result, a high molecular weight high ortho novolak resin having a content of low molecular weight components of 2 or less nuclei of 6.1% and a weight average molecular weight of 56000 was obtained.

Example 4
The same procedure as in Synthesis Example 2 was performed except that 100 parts of metacresol and 41 parts of 37% formalin were used as phenols. As a result, a high molecular weight high ortho novolac resin having a low molecular weight component content of less than 2 nuclei of 5.5% and a weight average molecular weight of 60,300 was obtained.

Comparative Example 1
A flask equipped with a condenser and a stirrer was charged with 100 parts of phenol, 0.5 part of oxalic acid, and 20 parts of methyl isobutyl ketone, the internal temperature was 150 ° C., and 69 parts of 37% formalin was added dropwise over 3 hours. Since methyl isobutyl ketone and water azeotrope during the dropwise addition, water was removed and methyl isobutyl ketone was refluxed.
After completion of the dropwise addition, the mixture was reacted at the same temperature for 1 hour, and then 170 ° C., 6666 Paabs.
Unreacted phenol was removed by steam distillation under reduced pressure (50 mmHgabs). As a result, a novolak resin having a low molecular weight component content of 12.2% or less and a weight average molecular weight of 51,500 was obtained.

Comparative Example 2
A flask equipped with a condenser and a stirrer was charged with 100 parts of phenol, 0.5 part of zinc acetate, and 20 parts of methyl isobutyl ketone, the internal temperature was 130 ° C., and 69 parts of 37% formalin was added dropwise over 3 hours. During the dropwise addition, water was not removed, and the reaction was performed under normal pressure reflux. As a result, the internal temperature gradually decreased to 100 ° C.
After completion of the dropwise addition, the mixture was aged at 100 ° C. for 1 hour and then washed with water several times to remove the catalyst. Next, steam distillation was performed under reduced pressure at 170 ° C. and 6666 Paabs (50 mmHgabs). As a result, unreacted phenol was removed, and a novolak resin having a low molecular weight component content of 9.9% or less and a weight average molecular weight of 23200 was obtained.

Comparative Example 3
Comparative Example 2 was carried out except that the steam distillation was carried out at 170 ° C. and 20000 Paabs (150 mmHgabs). As a result, a novolak resin having a content of low molecular weight components of 2 nuclei or less of 13.1% and a weight average molecular weight of 15600 was obtained.

Comparative Example 4
A flask equipped with a condenser and a stirrer was charged with 100 parts of phenol, 69 parts of 37% formalin, and 0.5 part of zinc acetate and refluxed at 100 ° C. for 5 hours. Next, steam distillation was performed under reduced pressure at 170 ° C. and 6666 Paabs (50 mmHgabs) to remove unreacted phenol. As a result, a novolak resin having a low molecular weight component content of 10.4% or less and a weight average molecular weight of 19,700 was obtained.
Table 1 shows the characteristic values of the novolak resins obtained in Examples 1 to 4 and Comparative Examples 1 to 4.

Examples 5-8, Comparative Examples 5-8
An ortho-cresol type epoxy resin (epoxy equivalent 205) is equivalent to a phenolic hydroxyl group in each of the high molecular weight high ortho novolak resin obtained in Examples 1 to 4 and the novolak resin obtained in Comparative Examples 1 to 4. The curing accelerator triphenylphosphine was added to 1 part of 100 parts of the epoxy resin, and the fused silica powder was added to 70% of the total weight of the composition as a filler. These were melt-kneaded with a hot roll at 100 ° C. to obtain a thermosetting resin composition.
The obtained thermosetting resin composition was pressure-molded in a mold at 170 ° C. for 15 minutes at a pressure of 30 kg / cm ² . Thereafter, after-curing was performed at 170 ° C. for 3.5 hours to prepare a test piece. These were made to correspond to said order, and were set as Examples 5-8 and Comparative Examples 5-8.

About the thermosetting resin composition of this invention and the sample of the comparative example, bending strength was evaluated by the following method.
(5) Bending strength It measured by the method based on JISK-6911.
Table 2 shows the results of the characteristic evaluation tests for Examples 5 to 8 and Comparative Examples 5 to 8.

＊１ 熱ロール混練中に増粘したため成型品得られず
以上の実施例から、本発明方法で製造される高分子量ハイオルソノボラック樹脂は、未反応フェノールが少なく、かつ、オルソーオルソ結合比率が非常に高く、軟化点も高いことがわかる。また、オルソーオルソ結合比率が高いため、分子が直鎖状となり、その結果、それを用いた成形物の靭性が向上したことが分かる。

* 1 Molded product could not be obtained due to thickening during hot roll kneading From the above examples, the high molecular weight high ortho novolac resin produced by the method of the present invention has little unreacted phenol and a very high ortho ortho bond ratio. It can be seen that it has a high softening point. Moreover, since the ortho-ortho bond ratio is high, it can be seen that the molecule is linear, and as a result, the toughness of the molded product using the molecule is improved.

  The high molecular weight high-ortho novolak resin obtained by the method of the present invention has few volatile components even at high temperatures. For example, when it is used as a curing agent for an epoxy resin, a molded product having excellent heat resistance can be obtained. Moreover, since the ratio of the ortho-ortho bond is high, the molecule becomes linear, and as a result, the toughness of the molded product is improved, and the pot life of the epoxy compound is further increased. is there.

Claims (4)

And phenols, Ca, Mg, and a weakly acidic catalyst consisting of either the acetate or borate divalent metal selected from Zn, in the presence of an organic solvent, and sequentially adding aldehyde with the reaction, a method of producing a high molecular weight high-ortho novolak resin you remove water in the system, the weight average molecular weight of the high molecular weight high-ortho novolak resin is 10,000 or more, ortho to the total methylene bonds - ortho and a coupling ratio of 75% or more, such that the reaction temperature is 130 to 180 ° C., a method for manufacturing high molecular weight high-ortho novolak resin having a boiling point, characterized in Rukoto using an organic solvent in the range of 80 to 180 ° C. . 2. The high molecular weight high-ortho novolak resin according to claim 1, further comprising a step of removing unreacted phenols by distillation under reduced pressure, wherein a distillation temperature in the removing step is 180 ° C. or lower and a degree of vacuum is 6666 Paabs (50 mmHgabs) or lower. Manufacturing method. The azeotropic mixture of water and an organic solvent produced in the reaction solution is discharged out of the reaction system, and after separating the water, the organic solvent is refluxed into the reaction system. Method for producing ortho-novolak resin. The manufacturing method of the high molecular weight high ortho novolak resin in any one of Claims 1-3 which removes a residual catalyst by washing the reaction liquid with water.