JPS5825685B2 - Manufacturing method of novolac resin for textile raw materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a novolac resin for textile raw materials, and more specifically, to an improvement in the method for reacting phenols with taldehydes.

It is known that novolak resin is used as a raw material to produce fibers used for various purposes.

For example, novolac resin is melt-spun into fibers,
Then, by curing, phenolic resin fibers with excellent heat resistance, flame resistance, and low-temperature properties can be obtained.

The novolac resin used as such a fiber raw material is different from the novolac resin used as a general molding material, and its physical properties are strictly limited.

For example, when a normal novolac resin is heated, it gradually hardens and its physical properties change, such as an increase in viscosity, but in the case of a raw material for fibers, it is desirable to use a resin that is as thermally stable as possible.

It is also required that there are no foreign substances in the resin.
It is also necessary that the melt viscosity of the resin be as constant as possible.

Furthermore, fibers that are simply melt-spun are extremely brittle and cannot be used as practical fibers, so these fibers are cross-linked and cured, or cured, using an acid-formalin aqueous solution, etc., to become insoluble and infusible fibers. It must proceed smoothly.

Among these, the most important thing for use as a fiber raw material is that the resin has good thermal stability and that the melt viscosity does not change.

Generally, in order to manufacture fibers using novolac resin, for example, the novolac resin is subjected to rapid distillation under reduced pressure and heat to remove unreacted phenol, water, and other impurities, and foreign substances are filtered. After performing purification treatments such as filtration and removal, the fibers are melt-spun, and then cross-linked and cured in a hydrochloric acid-formalin solution to obtain insoluble and infusible novolak fibers.

In the manufacturing process of this fiber, the novolac resin obtained by polycondensation reaction has excellent thermal stability and the melt viscosity does not change during the refining process and melt spinning process, which is important for spinnability, curing uniformity, yarn quality, and yarn speed. From the viewpoint of retention, etc., this is something that is highly desired.

In particular, a novolac resin with good thermal stability that can withstand purification processes operated at high temperatures and whose melt viscosity does not change is desired.

The present inventors conducted various studies to obtain a novolac resin that is suitable for fiber raw materials and has good thermal stability during refining treatment.As a result, the crude novolac resin obtained by a conventional process was rapidly distilled under reduced pressure and heating. It has been found that the distillate obtained from this process has a significant effect on the thermal stability of novolak resin.

That is, the present invention relates to improving the thermal stability of novolac resin by rapidly distilling a crude novolac resin obtained by reacting phenols and aldehydes in the presence of an oxalic acid catalyst under reduced pressure and heating to produce a novolac range for textiles. The present invention provides a method for producing a novolac resin for fiber raw materials, characterized in that the reaction is carried out in the presence of a distillate from the rapid distillation.

The present invention will be explained in detail below. The phenols used in the present invention include phenol, cresol,
xylenol, phenylphenol, bisphenol A
and mixtures thereof.

Examples of aldehydes include formaldehyde, paraformaldehyde, and furfural.

Formaldehyde is conveniently used in the form of an aqueous solution, particularly in the form of an aqueous solution (formalin) with a concentration of 37 to 48%, industrially.

Oxalic acid is selectively used as catalyst.

The amount of oxalic acid used, the molar ratio of phenols to aldehydes, and other reaction conditions may be determined in accordance with known methods.

To illustrate one particularly preferred method, the amount of oxalic acid used is 0.2 to 1.5% by weight based on the phenols, and the molar ratio of phenols/aldehydes is 1.12 to 1.3.
It is 0.

The aldehyde may be added to the reaction system all at once, or continuously or at intervals within a certain period of time.

The reaction temperature is preferably 60 to 150°C, and the total time required for one reaction is preferably 2 to 8 hours.

The reaction is usually carried out under normal pressure and total reflux, and after the completion of the polycondensation reaction, the temperature of the system is raised to 140 to 180°C to carry out evaporative dehydration and to thermally decompose and deactivate oxalic acid.

The crude novolac resin obtained by such O-filtering contains unreacted phenol, water, etc., and is therefore rapidly distilled under reduced pressure and heating.

This rapid distillation is carried out, for example, under reduced pressure of 100 degrees Hg or less and under heating at 160 to 220 DEG C., according to a conventional method.

The most significant feature of the present invention is that the above-mentioned polycondensation reaction of phenols and aldehydes is carried out in the presence of a distillate obtained by rapid distillation (hereinafter simply referred to as distillate). It's my turn.

More specifically, it is carried out by adding a small amount of distillate before the start of the polycondensation reaction or at the beginning of the reaction.

The composition of the distillate from rapid distillation depends on the composition of the crude novolac resin to be subjected to rapid distillation and the conditions of rapid distillation.

The crude novolac resin used in the present invention is produced by reacting phenols and aldehydes under reflux conditions using water as a reaction medium, and then heating under non-reflux conditions to partially remove unreacted phenol, water, etc. It is obtained as a residue after distillation.

However, this crude novolak resin usually contains 3 to 20%, especially 5 to 15%, of phenols, 5% or less of water, especially about 0.5 to 3%, and 5 to 5% of other structurally unknown components. % or less, especially 1 to 3%.

On the other hand, rapid distillation is carried out by processing the crude novolac resin into a thin film under reduced pressure and heating.

The degree of reduced pressure is 100 mmHg or less, preferably 60 r.
NrnHg or less is better, heating temperature is 130-250℃,
Preferably, the temperature is selected from the range of 160 to 220°C.

When the crude novolak resin is subjected to rapid distillation as described above, the distillate of the present invention is obtained.

This distillate contains 60 to 90% of phenols, especially I'C7.
It contains 5 to 85% of water, 1 to 8%, especially 2 to 4% of water, and 5 to 20% of components of unknown structure.

The amount of distillate that should be present when reacting phenols and aldehydes is 0.0% relative to the phenols.
It is selected from the range of 5 to 20%, preferably 0.2 to 10%.

If the amount present is too small, the effects of the present invention cannot be fully exerted,
On the other hand, if the amount is too high, there is no particular problem since the main components are phenols and water, but components of unknown structure in the reaction system will also increase, and depending on the case, it may cause coloring of the crude novolak. , usually in a proportion of 20% or less relative to phenols.

In order for the distillate to be present in the reaction system, it is preferable to add the necessary amount before the start of the polycondensation reaction, but it is preferable to add it in the early stage of the reaction when the reaction has not progressed much, for example, within 1 hour from the start of the reaction. It may be a method.

The polycondensation reaction is usually carried out for 2 to 8 hours.

The crude novolak obtained by reacting ζphenols and aldehydes in the presence of a distillate as described above has extremely good thermal stability.

The reason for this is not clear at present, but it is presumed that a small amount of components of unknown structure present in the distillate have a slight influence.

Conventionally, this distillate was distilled again to remove structurally unknown components, and phenol was recovered in a purified form, which was recycled for use in the polycondensation reaction.

It was an unexpected discovery by the present inventors that a structurally unknown component in the distillate contributes to the thermal stability of novolac resin.

As detailed above, according to the method of the present invention, when reacting phenols and aldehydes in the presence of an oxalic acid catalyst, thermal stability can be achieved by adding a small amount of distillate obtained by rapid distillation. Novolac resin for fiber raw materials with excellent properties can be produced industrially and advantageously.

Furthermore, the yield of phenols is improved throughout the entire process of novolak resin production, which is advantageous from this point of view as well.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples; however, the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Reference Example 1 100 parts of phenol (parts by weight, the same applies hereinafter) was placed in a reaction vessel, then 5 parts of a 10% aqueous oxalic acid solution was added, and 100 parts of phenol was added.
It was kept at 0°C.

To this, 73 parts of 37% formalin was added continuously at a constant flow rate over 1.0 hour, and after the addition was completed, the reaction was carried out under total reflux at normal pressure over 2 hours.

After dehydration under normal pressure, the reaction product, novolac resin, was heated to 160° C. to complete the reaction.

The crude novolac resin thus obtained was
Rapid distillation was performed at a temperature of 210° C. under reduced pressure of Hg to dehydrate and remove phenol, and the gas phase was cooled to 60° C. to obtain an evaporative distillate.

This distillate contained 83.2% by weight of phenol, 2.6% by weight of water, and 14.2% by weight of other substances of unknown structure.

Example 1 100 parts of phenol was charged into a reaction vessel, and then 10%
5 parts of oxalic acid aqueous solution was added and kept at 100°C.

To this was added 0.3 parts of the distillate obtained in Reference Example 1 (0.3% by weight based on phenol), and then 73 parts of 37% formalin was added continuously at a constant flow rate over 1.0 hour. did.

Further, the reaction was carried out under total reflux at normal pressure over a period of 2 hours after the addition was completed.

After dehydration under normal pressure, the crude novolac resin as a reaction product was heated to 160° C. to complete the reaction.

The crude novolak resin thus obtained was
Dehydration and dephenolization were performed by rapid distillation at a temperature of 210°C under reduced pressure of Hg, and filtration was performed using a filter to obtain a total of 10
The purification process required several hours of residence time.

In this purification treatment, the rate of increase in the intrinsic viscosity of the purified product obtained relative to the intrinsic viscosity of the novolac resin before treatment was 0.3%, which was sufficiently small and the novolac resin had excellent thermal stability during the purification treatment.

Comparative Example 1 In Example 1, a banko reaction was carried out without adding the distillate obtained in Reference Example 1.

After dehydration under normal pressure, the resin was heated to 160° C. to complete the reaction.

The crude novolak resin thus obtained was used in Example 1.
When the refining treatment was performed in the same manner as above, the increase rate of the intrinsic viscosity of the obtained purified product was 10% compared to the intrinsic viscosity of the novolac resin before the refining treatment. Met.

Example 2 In Example 1, 0.7 part of the distillate obtained in Reference Example 1 (
After adding 0.7% by weight based on phenol, the reaction was carried out.

After that, the reaction was completed by dehydration and temperature raising in the same manner as in Example-1, and then purification treatment was performed.The intrinsic viscosity of the obtained purified product increased, whereas the intrinsic viscosity of the novolac resin before the purification treatment was 0. The novolac resin had a sufficiently small ratio of 0.2% and had excellent thermal stability during purification treatment.

Example 3 In Example 1, 90 parts of Pheno-Jv was charged, and 10 parts of the distillate obtained in Reference Example 1 were added, followed by a reaction.

After dehydration under normal pressure, the resin was heated to 160° C. to complete the reaction.

This novolak resin was slightly yellowish compared to Example 1, but this did not pose any particular problem in terms of quality such as intrinsic viscosity.

After that, the same purification treatment as in Example 1 was performed, and the rate of increase in the intrinsic viscosity of the obtained purified product was 0.3%, which was sufficiently small compared to the intrinsic viscosity of the novolac resin before the purification treatment. It was a novolac resin with excellent thermal stability.

Claims (1)

[Claims] 1 In a method for producing a novolac resin for textile raw materials by rapidly distilling a crude novolac resin obtained by reacting phenols and aldehydes in the presence of an oxalic acid catalyst under reduced pressure and heating, the reaction is carried out during the rapid distillation. A method for producing a novolac resin for textile raw materials, characterized in that the method is carried out in the presence of a distillate of.