JP2005075937A - Manufacturing process of novolac type phenolic resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for manufacturing a novolac type phenolic resin which contains only a small amount of unreacted phenols and has a narrow molecular weight distribution in a high yield for a short period of time. <P>SOLUTION: The process for manufacturing a novolac type phenolic resin comprises reacting a phenol and an aldehyde at ≥120°C using an aqueous phosphoric acid solution in a hermetically sealed apparatus and using not less than 0.2 mole of the phosphoric acid per 1 mole of the phenol. Preferably, the reaction is carried out by simultaneously charging the phenol, the aldehyde and the phosphoric acid in the apparatus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a novolac type phenolic resin.

Conventionally, novolac-type phenol resins have been obtained by reacting phenols and aldehydes with an inorganic acid or organic acid such as hydrochloric acid, sulfuric acid, oxalic acid, and p-toluenesulfonic acid as a catalyst.
The molecular weight of the novolak-type phenol resin is generally adjusted by the charged molar ratio of phenols and aldehydes, but the novolak-type phenol resin having a low molecular weight tends to have a wide molecular weight distribution. As a general means for narrowing the molecular weight distribution, there are a method of reacting in an organic solvent and a method of removing low molecular weight components by steam distillation or solvent washing. In the former case, a low molecular weight novolak type phenol resin can be obtained. In the latter case, the yield is greatly reduced. Moreover, both require a long time for the reaction operation (for example, refer nonpatent literature 1).

Akihiro Matsumoto, “Synthesis / curing / toughening and application of phenolic resin”, IPC Corporation, January 20, 2000, p. 12-18

  The present invention provides a method for producing a novolak type phenol resin with a small amount of unreacted phenols and a narrow molecular weight distribution in a short time and in a high yield.

Such an object is achieved by the following present inventions (1) to (4).
(1) A method for producing a novolak-type phenol resin in which phenols and aldehydes are reacted at 120 ° C. or higher in an airtight device using an aqueous phosphoric acid solution, wherein the phosphoric acids 0 are added to 1 mol of the phenols. A method for producing a novolac-type phenolic resin, wherein 2 mol or more is used.
(2) The method for producing a novolac type phenol resin according to the above (1), wherein the phenols and the aldehydes are collectively charged and reacted together with the phosphoric acid aqueous solution.
(3) The method for producing a novolac type phenol resin according to the above (1) or (2), wherein the reaction is carried out at a water content of 1 to 40% by weight in the reaction system.
(4) The method for producing a novolac type phenol resin according to any one of (1) to (3), wherein the phosphoric acid is phosphoric acid.

  The present invention is characterized in that phenols and aldehydes are reacted at 120 ° C. or higher in a sealed apparatus using an aqueous phosphoric acid solution containing 0.2 mol or more of phosphoric acid per mol of phenol. The novolak type phenol resin is a method for producing a novolak type phenol resin having a small amount of unreacted phenols and a narrow molecular weight distribution in a short time with a high yield.

Hereinafter, a method for producing the novolak type phenolic resin of the present invention (hereinafter sometimes simply referred to as “manufacturing method”) will be described.
The production method of the present invention is a method for producing a novolac-type phenol resin in which phenols and aldehydes are reacted at 120 ° C. or higher in a sealed device using an aqueous phosphoric acid solution, and the phenols and aldehydes are reacted with 1 mol of the phenols. The phosphoric acid is used in an amount of 0.2 mol or more.

Although it does not specifically limit as phenols used with the manufacturing method of this invention, For example, it has phenolic hydroxyl groups, such as a phenol, metacresol, 3, 5- xylenol, and it exists at least other than the position of meta with respect to a phenolic hydroxyl group. One or two or more of compounds having no substituent can be suitably used.
In addition to the above, trifunctional phenols having an alkyl group or aryl group having a large number of carbon atoms as a substituent can also be used, but phenol and / or metacresol are preferred in view of curability.
That is, in phenols having a large substituent, although the molecular weight is increased, the number of phenol nuclei at the same molecular weight is decreased, leading to a decrease in the number of hydroxyl equivalents, etc., and subsequent three-dimensional due to steric hindrance by the substituent. Cross-linking may be difficult.
In addition, resorcin can be used as phenols as long as gelation does not occur during the reaction.

  In addition, the aldehydes used in the production method of the present invention are not particularly limited. It is also possible to use a substance that is a source of aldehydes or a solution of these aldehydes.

Although the reaction molar ratio (F / P) of aldehydes (F) and phenols (P) is not particularly limited, it is preferably 0.1 to 3.0, more preferably 0.5 to 1. 0. Most preferably, it is 0.6-0.8.
When the reaction is carried out under a condition where the reaction molar ratio is lower than the lower limit, the yield tends to be low, and the molecular weight tends to be too small even as a novolak type phenol resin. On the other hand, when the reaction molar ratio exceeds the above upper limit, the molecular weight tends to be difficult to control, and depending on the reaction conditions, gelation or partial gelation may occur.

In the production method of the present invention, phenols and aldehydes are reacted at 120 ° C. or higher using an aqueous phosphoric acid solution. Preferably it is 130 degreeC or more. Thereby, a novolac type phenol resin can be produced in a high yield in a short time.
Although it does not specifically limit as a method of making it react at the said temperature or more, It is preferable to carry out batch reaction of phenols and aldehydes with phosphoric acid aqueous solution collectively. As a result, if the temperature of the reaction system is raised to a predetermined temperature, the temperature of the reaction system can be quickly increased to the above temperature or more rapidly due to the large exotherm associated with the reaction between phenols and aldehydes. Can be advanced.
Usually, in the production of a novolac type phenol resin, a method such as sequential addition of aldehydes is employed in order to suppress this exotherm, but in the production method of the present invention, the reaction is shortened by utilizing this exotherm. Can be completed in time.

Moreover, in the manufacturing method of this invention, phenols and aldehydes are made to react in a sealing apparatus with phosphoric acid aqueous solution. When reaction is carried out under normal pressure using an open reactor, components such as phenols, aldehydes and moisture in the reaction system suddenly boil and overflow from the reactor if the reaction system suddenly generates heat. Or it may be difficult to raise the temperature further due to boiling of the above components.
In the present invention, by reacting in a sealed device, such a problem can be avoided and the reaction can proceed efficiently in a short time. In addition, although it does not specifically limit as a sealing device here, For example, an autoclave etc. are mentioned.

  In the production method of the present invention, the phenols and aldehydes are reacted using an aqueous solution of phosphoric acid, and 0.2 mol or more of the phosphoric acid is used with respect to 1 mol of phenols. .

  Here, as the phosphoric acid, a phosphoric acid compound that can be dissolved in water to form a phosphoric acid aqueous solution can be used, and is not particularly limited. For example, phosphoric acid (orthophosphoric acid), diphosphoric acid, triphosphoric acid, etc. In addition to linear polyphosphoric acid, cyclic polyphosphoric acid, diphosphorus pentoxide, phosphorous acid, hypophosphorous acid and the like, various phosphoric acid ester compounds can be mentioned. These can be used alone or in combination of two or more.

  Of these phosphoric acids, phosphoric acid is preferred. Phosphoric acid can be easily adjusted in concentration and can be obtained at low cost.

  Although it does not specifically limit as a density | concentration of phosphoric acid in this phosphoric acid aqueous solution, It is preferable that it is 20 to 99 weight%, More preferably, it is 40 to 99 weight%. By setting the concentration of phosphoric acid in the phosphoric acid aqueous solution to the above lower limit or more, the reaction between phenols and aldehydes can be efficiently advanced.

The amount of phosphoric acid used in the production method of the present invention is 0.2 mol or more per 1 mol of phenols. Thereby, in the system which reacts phenols and aldehydes using phosphoric acid aqueous solution, distribution with the organic phase which has phenols as a main component, and the aqueous phase which consists of phosphoric acid aqueous solution can be stabilized.
The amount of the phosphoric acid is more preferably 0.3 to 1.0 mol, and particularly preferably 0.4 to 0.9 mol, with respect to 1 mol of phenols. Thereby, a novolak type phenol resin having a narrow molecular weight distribution and less unreacted phenols can be obtained efficiently.

  Increasing the amount of phosphoric acid tends to increase the effect of obtaining a high yield of novolak-type phenolic resin with a low content of unreacted phenols and a narrow molecular weight distribution. On the other hand, use of an amount exceeding 1.0 mol may not be economical because this effect is substantially unchanged. On the other hand, if the amount is less than 0.2 mol, the phosphoric acid concentration in the aqueous phase is too low to stably distribute the organic phase and the aqueous phase, so that the reaction rate decreases.

  In the production method of the present invention, the amount of water in the reaction system is not particularly limited, but is preferably 1 to 40% by weight. This reaction condition is effective for selectively reacting not only unreacted phenols but also low molecular weight novolak type phenol resins such as dinuclear and trinuclear compounds, and effectively narrowing the molecular weight distribution. it can. In other words, the reaction of unreacted phenols can be carried out sufficiently even outside the range of the above reaction conditions, but it is insufficient for the selective reaction in the low molecular weight region such as dinuclear or trinuclear. In this case, the molecular weight distribution tends to be wide.

In the production method of the present invention, the amount of water in the reaction system is the amount of water with respect to phenols, aldehydes, novolac-type phenol resins, phosphoric acids and the like existing in the system. Water includes water added during charging, water contained in aldehydes added, water contained in aqueous phosphoric acid solution added, water crystallized from phosphoric acids, water derived from raw materials, condensed water generated during reaction, etc. There is.
The water content in these reaction systems is preferably 1 to 40% by weight, more preferably 1 to 30% by weight. The method for calculating the amount of water in the reaction system is a value obtained by dividing the amount of water in the charged raw material and the amount of condensed water produced by the reaction as the amount of water in the reaction system, and dividing this by the total amount charged.
The smaller the amount of water, the smaller the amount of unreacted phenols and the higher the yield of a novolak type phenol resin with a narrow molecular weight distribution. In this respect, 40% by weight or less is preferable, and 30% by weight or less is more preferable in order to further enhance the effect. However, if the water content is too low, the phosphoric acids will increase in viscosity or solidify and the catalytic action will decrease, so that the water content to the extent that it contains crystal water is preferably 1% by weight or more. When the water content exceeds 40% by weight, the effect is hardly changed.

  In the production method of the present invention, the stirring speed during the reaction is not particularly limited, but a higher stirring speed is preferred. This is because the aqueous phase containing the catalyst and the organic phase containing phenols do not melt together and the reaction proceeds in a non-uniform state, so the higher the stirring speed, the more the contact interface between the aqueous phase and the organic phase increases. This is because the process proceeds efficiently.

  After completion of the reaction, neutralization or washing with water may be performed to remove the catalyst. Moreover, in order to remove water, an organic solvent, and also unreacted phenols as needed, it is possible to perform atmospheric distillation, vacuum distillation, steam distillation or the like.

In the production method of the present invention, the reason why a novolak type phenol resin having a narrow molecular weight distribution can be obtained in high yield using phosphoric acids as a catalyst is considered as follows.
The phosphoric acids used in the present invention are very water-soluble. However, the phenols have low solubility, and the novolak type phenol resin has the property that the solubility is further reduced as the molecular weight increases. For this reason, at the time of reaction, it will be in the state which phase-separated into the organic phase which consists of phenols and a novolak-type phenol resin which hardly contains a catalyst, and the aqueous phase which contained phosphoric acid which is a catalyst in large quantities. Low molecular components such as phenols and dinuclear substances are relatively easily eluted in the aqueous phase, and the eluted part reacts with aldehydes. However, in the polymer region, there is almost no elution and the reaction does not proceed. In addition, the novolak-type phenol resin eluted and reacted in the aqueous phase is quickly extracted into the organic phase, and the reaction does not proceed further.
In this way, a difference in reaction rate between the low molecular weight region and the high molecular weight region occurs, and as a result, a novolak resin having a small amount of unreacted phenols and a narrow molecular weight distribution can be produced in a high yield.

In the production method of the present invention, an aqueous phosphoric acid solution is used as a catalyst, the reaction temperature is 120 ° C. or higher, and preferably, the reaction system has a water content of 1 to 40% by weight as a reaction condition. And
By setting the reaction temperature to a high temperature of 120 ° C. or higher, the following effects can be obtained. Because of the high temperature, low molecular weight regions such as dinuclear and trinuclear bodies are easily eluted into the aqueous phase, and the reaction in the aqueous phase easily proceeds. In addition, the reaction rate is improved due to the high temperature. When the water content in the reaction system is 1 to 40% by weight, the water content is low and the catalyst concentration in the water phase is maintained high, and the water phase and the organic phase are more securely separated. The reaction on the organic phase side can be suppressed. Moreover, although phosphoric acid has the property to raise a viscosity or to solidify when it is high concentration, since it is high temperature, it can be in the molten state and can prevent losing a catalyst function. From these effects, the effect of obtaining a novolak-type phenol resin with a small amount of unreacted phenols and a narrow molecular weight distribution in a high yield in a short time is enhanced.

  The molecular weight distribution of the novolak-type phenolic resin obtained by the production method of the present invention is the number average molecular weight (Mn) in terms of polystyrene and the weight average molecular weight (Mw) measured by liquid chromatography such as gel permeation chromatography (GPC). ) (Mw / Mn) in terms of the value (dispersion degree). In general, in a high molecular weight compound having a molecular weight distribution, Mw> Mn and the dispersity is a value larger than 1, and the smaller the value, the lower the dispersity and the narrower the molecular weight distribution.

  Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to the examples. In the examples and comparative examples, “%” represents all “% by weight”.

<Example 1>
In a 10 L closed reaction apparatus (autoclave) equipped with a stirrer and a thermometer, phenol 4000 g, 92% paraformaldehyde 971 g (molar ratio F / P = 0.7), and 85% phosphoric acid aqueous solution 4000 g (phosphoric acids / phenol) 1 mol = 0.62 mol) was added and heated in a sealed state. When the internal temperature rose to 80 ° C., a rapid exothermic reaction occurred, and the internal temperature rose to 150 ° C. in about 3 minutes. At the same time, the pressure rose to 0.43 MPa. When the internal temperature decreased to 130 ° C., the pressure release cock was gradually opened, and the internal pressure was returned to atmospheric pressure via the cooling pipe. At this time, the internal temperature was 95 ° C. The internal temperature was cooled to 60 ° C. and allowed to stand for 10 minutes. After standing, the aqueous phosphoric acid solution was separated and removed from the bottom of the reactor. After completion of the separation, 4000 g of water was added and stirred for 15 minutes at an internal temperature of 80 to 90 ° C. to wash the remaining catalyst. After standing for 10 minutes, washing water was removed from the upper part of the reactor. A dehydration pipe was attached here, and atmospheric pressure dehydration was performed up to an internal temperature of 130 ° C., followed by vacuum dehydration up to an internal temperature of 150 ° C. at 5000 Pa to remove moisture and the like in the system. The obtained resin was taken out from the reactor into a vat to obtain 5245 g of a novolac type phenol resin.
The number average molecular weight (Mn) of the obtained resin by GPC was 510, the weight average molecular weight (Mw) was 800, and the degree of dispersion (Mw / Mn) was 1.57. Moreover, the unreacted phenol component was 0.6%. The time required for the reaction was 2 hours and 15 minutes in total.

<Example 2>
Except that the charged amount of 92% paraform was changed to 1040 g (F / P = 0.75), the same procedure as in Example 1 was performed to obtain 4300 g of a novolac type phenol resin.
The number average molecular weight (Mn) by GPC of the obtained resin was 660, the weight average molecular weight (Mw) was 890, and the dispersity (Mw / Mn) was 1.35. Moreover, the unreacted phenol component was 0.2%. The time required for the reaction was 2 hours and 10 minutes in total.

<Comparative Example 1>
A 10 L reactor equipped with a stirrer, a condenser and a thermometer was charged with 7000 g of phenol and 70 g of oxalic acid, heated to an internal temperature of 95 ° C. at normal pressure, and then 3864 g of 37% formalin (F / P = 0.64). Was added over 1 hour. Furthermore, after refluxing reaction at 98-100 degreeC for 1 hour, it heated up to 140 degreeC, removing the water produced | generated by switching to dehydration piping. Next, while gradually reducing the pressure in the kettle to 5000 Pa, the internal temperature was raised to 250 ° C. to remove moisture and the like, and 6090 g of a novolac type phenol resin was obtained.
The number average molecular weight (Mn) by GPC of the obtained resin was 720, the weight average molecular weight (Mw) = 1580, and the dispersity (Mw / Mn) = 2.19. The unreacted phenol component was 0.4%. The total time required for the reaction was 4 hours 30 minutes.

<Comparative example 2>
A 10 L reactor equipped with a stirrer, a cooling tube and a thermometer was charged with 3000 g of phenol and 3000 g of 85% phosphoric acid aqueous solution, heated to an internal temperature of 95 ° C. at normal pressure, and then 728 g of 92% paraformaldehyde (F / P = 0.70) was added over 1 hour. Furthermore, refluxing reaction was performed at 98-100 degreeC for 1 hour. The internal temperature was cooled to 60 ° C. and allowed to stand for 10 minutes. After standing, the aqueous phosphoric acid solution was separated and removed from the bottom of the reaction apparatus. After completion of the separation, 3000 g of water was added and stirred for 15 minutes at an internal temperature of 80 to 90 ° C. to wash the remaining catalyst. After standing for 10 minutes, washing water was removed from the upper part of the reactor. A dehydration pipe was attached here, and atmospheric pressure dehydration was performed up to an internal temperature of 130 ° C., followed by vacuum dehydration up to an internal temperature of 150 ° C. at 5000 Pa to remove moisture and the like in the system. The obtained resin was taken out from the reactor into a vat to obtain 4292 g of a novolac type phenol resin.
The number average molecular weight (Mn) by GPC of the obtained resin was 520, the weight average molecular weight (Mw) was 790, and the degree of dispersion (Mw / Mn) was 1.52. Moreover, the unreacted phenol component was 0.4%. The total time required for the reaction was 4 hours and 10 minutes.

  The results for the resins produced in the examples and comparative examples are shown in Table 1. The yield value was calculated from the value for the theoretical yield. Moreover, the measuring method of each physical property value is as follows.

(Measuring method)
(1) Number average molecular weight (Mn), weight average molecular weight (Mw), dispersity (Mw / Mn): measured by liquid chromatography.
・ Liquid chromatography:
Using a Tosoh GPC column (G1000HXL: 1, G2000HXL: 2, G3000HXL: 1) with a flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C as a differential refractometer as a detector GPC measurement was performed, and the molecular weight was converted by standard polystyrene.
(2) Unreacted phenol content: measured by gas chromatography.
-Gas chromatography: In accordance with JIS K0114, 2,5-xylenol was used as an internal standard and measured by an internal standard method.

In Examples 1 and 2, phenols and aldehydes are reacted at 120 ° C. or higher in a sealed apparatus using an aqueous phosphoric acid solution containing 0.2 mol or more of phosphoric acid with respect to 1 mol of phenol. It was a phenolic resin obtained by the production method of the invention, and a novolak type phenolic resin having a small amount of unreacted phenol and a narrow molecular weight distribution could be obtained in a high yield in a short time.
On the other hand, Comparative Example 1 was a reaction using a normal oxalic acid catalyst, and the amount of unreacted phenol was small because it was removed by distillation under reduced pressure. However, it took a long time and the yield was low. In addition, the molecular weight distribution also became wider compared to the examples. In Comparative Example 2, since phosphoric acid was used as a catalyst, a resin with a small amount of unreacted phenol and a narrow molecular weight distribution was obtained. However, since the reaction was carried out at normal pressure, the reaction time was long.

  The production method of the present invention is suitable as a method for producing a novolac type phenol resin used for a binder such as a molding material, a friction material, a grindstone, and a sealing material.

Claims (4)

A method for producing a novolac-type phenol resin in which phenols and aldehydes are reacted at 120 ° C. or higher in an airtight device using an aqueous phosphoric acid solution, and 0.2 mol of the phosphoric acid per 1 mol of the phenol A method for producing a novolac-type phenolic resin characterized by using the above. The method for producing a novolac type phenol resin according to claim 1, wherein the phenols and the aldehydes are collectively charged and reacted together with the phosphoric acid aqueous solution. The method for producing a novolac type phenol resin according to claim 1 or 2, wherein the reaction is carried out with a water content in the reaction system of 1 to 40% by weight. The method for producing a novolac type phenol resin according to any one of claims 1 to 3, wherein the phosphoric acid is phosphoric acid.