FI63591C - FOERFARANDE FOER FRAMSTAELLNING AV ETT SURT AEMNE - Google Patents

Abstract

Mixing a sulphonated phenol with formaldehyde and reacting at elevated temperature produces an acidifier in a continuous manner. The mixing and reacting are carried out at a constant molar ratio of the reactants, at a temperature from 50 to 120 DEG C and in an "ideal" displacement reactor. The acidifier obtained can be used as a catalyst for curing phenol resols (resoles) and as a synthetic tanning agent in the leather industry.

Description

ΓβΊ / ^ ADVERTISEMENT PUBLICATION / 7rQ1 Jua lBJ '' utlAggnINGSSKRIFT 005 91 C (45) Patent granted 11 07 1903 Patent aeddelat VV (51) K ¥ .ik? /Int.a.3 C 08 G 8/18, 14/08, , Ö 14 C 3/18 FINLAND — FINLAND (21) PtMnttlhtkemu · —fatwNaMeknlnf 780035 (22) H »k * ml * pUvl - Anaeknlnfadtf 05.01.78 * '(13) Alku pilvi — GIMfhacadai 05.01.78 (41) Translators JulklMks - Whrtt off «mll | 07 07 78

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PatMit-och regiiterctyralMn '' Aiwttktn uttajd och utl. * Krtft * n puMtoand 31.03.83 (32) (33) (31) Pjrydttty atuoikaui —Begird priority 06. 01. 77 06.01.77 USSR (SU) 21 + 392 ^ 0 , 2UU1696 (71) Vsesojuzny Nauchno-Issledovatelsky Institut Sinteticheskikh Smol, ulitsa Frunze 77, Vladimir, USSR (SU) (72) Vasily Dmitrievich Valgin, Vladimir, Alexandr Maximovich Vasilenko, Vladimir, Anatoly Yakovlevich Morozov, Rostovska oblast oblast, USSR (SU) (7 ^) Oy Kolster Ab (5M Method for the preparation of an acidic substance - Förfarande för framställning av ett surt ämne

The invention relates to a process for the preparation of an acidic substance by mixing sulfonated phenol and formaldehyde and reacting them at an elevated temperature and, if necessary, in the presence of processing aids. The substance according to the invention can be used as a catalyst in the curing of phenol-formaldehyde resoles and as a tanning agent in the leather industry.

A process for the preparation of an acidic substance is known in the art which involves condensing phenol with an aldehyde at 85-100 ° C for a few hours, after which the novolak is sulfonated with sulfuric acid at 100-110 ° C for 2-6 hours (GB Patents 1,361,045, 1,359,683).

The disadvantages of this prior art method are the intermittent flow of the process, the long duration of the technological cycle, the considerable power consumption and the considerable labor input.

The resulting acidic substance also has drawbacks, such as the high viscosity of the sulfonated novolak, the presence of free sulfuric acid, which can sometimes be considerable, the small number of phenoxy rings unsubstituted by sulfoxy groups 2,63591, which phenol rings are able to act as active formaldehyde acceptors. To reduce the viscosity, such an acidic substance must be diluted with water, which increases its corrosive effect.

Also known in the art is a process for the preparation of an acidic substance which is carried out in a batch reactor in two steps: in the first step, the phenol is reacted with sulfuric acid at a temperature of 125-150 ° C for 0.5-1.0 hours; in the second step, the product obtained from the first step is reacted with formaldehyde at a temperature of 30-50 ° C for 1-2 hours GB Patent 1,283 113) The disadvantages of the prior art process in this field are due to its intermittent nature and considerable power consumption due to the need for vigorous mixing.

The acidic substance obtained by this method is a relatively weak acceptor of the aldehyde released during the curing of phenol-aldehyde resoles and causes increased corrosive activity to the phenol-aldehyde resins cured by it.

A process for preparing a foam from a phenol aldehyde using an acidic substance as a catalyst comprising a condensation product of a sulphonated phenol, a nitrogen-containing organic compound belonging to the class of amines or formaldehyde and formaldehyde is also better known in the art.

Said acidic substance is prepared by a method using a batch reaction of sulfuric acid, phenol, a nitrogenous organic compound and an aldehyde in three steps. In the first step the phenol is reacted with sulfuric acid at 80-110 ° C for 2-24 hours, in the second step the sulfonated phenol is reacted with the nitrogen-containing compound at 40-70 ° C for 0.5-1 hours and in the third step the product is reacted with the aldehyde at 40-70 ° C for 0.25 hours (GB Patents 1,228,857 and 1,272,857).

The disadvantages of this prior method are due to the intermittent operation, the long duration of the tenological period, as well as the high labor input and the considerable need for energy.

The nitrogen-containing compound contained in said acidic substance reduces the corrosion effect of the cured phenol-aldehyde resins and also acts as an acceptor of the aldehydes evolved during the curing of phenol-formaldehyde resoles.

63591 Disadvantages of the acidic substance used in the prior art in this field are also, for example, the insufficient strength of the phenol-aldehyde resins cured by it. In addition, this acidic substance tends to crystallize at low temperatures, which in certain cases causes considerable technological difficulties.

Thus, all prior art methods have the following disadvantages: - the periodic nature of the method, resulting in - losses in both the starting material and the final product; - the long duration of the technological cycle; - significant need for energy and work.

It is an object of the present invention to provide a continuous process for producing an acidic substance which achieves high productivity and efficiency and which makes it possible to produce a product which has a low viscosity, a low corrosion effect and which does not crystallize at low temperatures.

The process for the preparation of an acidic substance according to the invention is characterized in that the mixing of the sulfonated phenol and formaldehyde and the reaction of the components are carried out in a suitable displacement device at a temperature of 50-120 ° C in a molar ratio of 1: 0.3 to 1: 0.5.

The process for producing an acidic substance according to the present invention is carried out according to an improved technological scheme, which gives high productivity with lower energy requirements and less workload compared to previous methods in the art.

The advantage of an acidic substance containing urea as a processing aid and prepared according to the invention is based on the fact that it does not tend to crystallize at low temperatures.

According to the present invention, the acidic substance is prepared continuously in a molar ratio of sulfonated phenol with formaldehyde in the range of 1: 0.3 to 1: 0.5. At these molar ratios, the substance contains essentially no free phenol, has good compatibility with water and a viscosity of at most 120 P at 20 ° C.

The acidic substance can be modified with various compounds such as alcohol, nitrogen-containing compound, metal sulfonate, orthophosphoric acid, and other suitable compounds selected for the acidic range of action according to the desired properties.

Thus, different implementations of the process for the preparation of the acidic substance are possible.

4,63591

According to one embodiment of the present invention, for the preparation of an acidic substance, the acceptor properties with respect to free aldehyde are improved by using urea as a processing aid and the molar ratio of sulfonated phenol, formaldehyde to urea is in the range 1: (0.4-1.2): (0.5-1, 0).

This function can, of course, also be performed by another nitrogenous compound, such as thiourea or dicyandiamide; however, for economic reasons (commercial availability and cheap price) urea is recommended.

According to another embodiment of the present invention, 5 to 20% by weight of orthophosphoric acid is used as a processing aid to improve the fire resistance of the acid-cured product to produce an acidic substance. Other flame retardants such as boric acid may also be used; however, the commercial availability and low cost of orthophosphoric acid makes it a preferred active ingredient that can be used as a solvent for sulfonated phenol.

In another embodiment, for the preparation of an acidic substance according to the invention, the addition of urea as a liquid solution in orthophosphoric acid is used to simplify the process technology.

The residence time of the reaction mixture in the reactor must not be shorter than that required to complete the exothermic reaction, deviation from this requirement will result in an uneven product. By selecting the appropriate temperature and dimensions of the reactor, it is possible to ensure the completion of the exothermic reaction in the reactor with a residence time of 0.5 to 10 minutes.

The main difference between the continuous process according to the present invention and the prior art (batch) process for the preparation of oligomeric acid is due to the different starting composition of the reaction mixture, the process according to the invention a methyl derivative when the aldehyde is carefully added to the reaction mixture. According to the present invention, the process takes place in a constant molar ratio of components, in contrast to the prior art method, which is carried out when the molar ratio of the components changes.

63591 These special circuits result in the excellent quality of the product made by the method of the present invention.

Another difference is that the process is considerably streamlined, i.e. the duration of the individual steps and thus of the whole process is considerably shortened. This makes it possible to significantly improve the technological and economic properties of the method.

The term "phenol" as used in the present invention refers to phenol per se and its derivatives such as isomeric cresols.

Concentrated sulfuric acid is preferably used as the sulfonating agent. However, this does not eliminate the possibility of using fuming sulfuric acid, for example.

For the purposes of the present invention, a sulfonated phenol is preferred; however, when urea is used as a processing aid, other arylsulfonic acids such as benzenesulfonic acid may also be used.

"Formaldehyde" is a 37% aqueous solution of formaldehyde, i. formalin; however, it is possible to use other aldehydes such as acetaldehyde.

Urea's mission, i.e. as a free formaldehyde acceptor, other unsubstituted or mono-substituted amides or amines may also be used; however, this does not seem economically necessary.

For the purposes of the present invention, a technological process diagram is recommended in which reaction products with a temperature higher than 70 ° C are removed from the displacement reactor to a special heat exchanger where they cool the starting components (phenol, sulfuric acid) to a temperature above 50 ° C. In this embodiment, after mixing the starting materials, the reaction mixture reaches a temperature of 110-180 ° C with the release of exothermic heat, which allows the phenol sulfonation reaction to be completed under conditions approaching adiabatic conditions in 0.5-5.0 minutes without using additional heat.

In the preparation of an acidic substance, it is advantageous in some cases to neutralize part of the sulfonated phenol in the acidic substance by means of a base, whereby metal sulfonates are formed. This modified implementation of the method according to the present invention makes it possible to reduce the corrosion effect of the acidic substance. In addition, the water and moisture absorption of resole resins cured with 6,63591 of this acidic substance is often reduced. Oxides, hydroxides, carbonates, borates and the like can be used as the neutralizing additive, i.e. bases and salts of weak acids of metals such as barium, calcium, copper, silver, zinc, tin, iron and the like, which are added in amounts not usually exceeding 0.1 mole per 1.0 mole of sulfonated phenol.

For a better understanding of the invention, some examples are set forth below in tabular form.

In all examples, the sulfonated phenol was used as a melt or solution in orthophosphoric acid. Phenol and formaldehyde were administered in liquid form.

The starting materials according to the compositions were fed by means of metering pumps to a flow-through reactor with a residence time of the reaction mixture of 0.5 to 10 minutes and a temperature of 50 to 120 ° C.

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