JP2007297574A - New method for producing resorcinol resin containing unreacted resorcinol in reduced amount - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a resorcinol resin having excellent flowability and having a reduced unreacted resorcinol content. <P>SOLUTION: This method for producing the resorcinol resin containing unreacted resorcinol in a reduced amount comprises reacting resorcinol with formaldehyde in the presence of an acidic catalyst, 2-butanol, and an aqueous solution of a resorcinol water solubility inhibitor which is a salt for inhibiting and limiting the water solubility of the resorcinol and the resorcinol resin, batching off a 2-butanol phase, distilling off the 2-butanol, heating the produced resorcinol resin to a melted state, and then blowing a gas inactive in the resorcinol resin on the surface of the resin to exhaust the gas and a sufficient amount of the unreacted resorcinol outside the system. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a resorcin resin. More specifically, the present invention relates to a method for producing a resorcin resin in which the amount of unreacted resorcin is reduced.

  The resorcinol formaldehyde resin is used as an adhesive, paint, curing agent, surface treatment agent, coating agent, and the like. The starting material, that is, the raw material resorcin is dissolved in water at room temperature, and after the curing reaction, it is changed to an insoluble and infusible resin, and its curing rate is fast, so it is a very useful resin. This resin is often used by adding an alkaline catalyst or an acidic catalyst to the raw materials resorcinol and formaldehyde, followed by heating and curing at the point of use. Precursor precondensates of formaldehyde resin may be used.

  This precursor prepolycondensate is obtained by reacting a low molar ratio of formaldehyde with resorcin under an acidic catalyst. In order to ensure fluidity, it is desirable that the average degree of polycondensation of the precursor prepolycondensate is low. For this purpose, the amount of formaldehyde must be sufficiently reduced relative to resorcin. The polycondensation degree distribution of the product can be expressed by the following theoretical formula as a function of the molar ratio of resorcin to formaldehyde.

  This equation assumes that the novolak-type reaction of resorcin and formaldehyde under an acidic catalyst is complete, both resorcin and formaldehyde are bifunctional molecules, and the two bonds of formaldehyde are bound to resorcin. ing. Here, D represents the weight ratio, that is, the weight fraction, of the reaction product having n resorcin nuclei in the molecule when formaldehyde is reacted in P mole with respect to 1 mole of resorcin. n is a measure of the degree of polycondensation because it indicates how many resorcins the reaction product is. Here, since the product of n = 1 represents unreacted resorcin, D when n = 1 represents the weight fraction of unreacted resorcin. Next, Table 1 shows calculated values and actually measured values of D corresponding to various P and n.

  The numbers 1, 2, 3, and 4 in this table indicate the calculation results of D according to the above equation when the values of P and n are changed. No. 5 is data calculated from each peak area of gel permeation chromatography (hereinafter abbreviated as GPC), which is almost consistent with the data of No. 3 in the case of P having the same value. ing.

  As is obvious from the above table, it is most effective to lower the molar ratio of formaldehyde to resorcin to lower the molecular weight of the precursor prepolycondensate. But of course there are major obstacles here. That is, a large amount of unreacted resorcin remains. Resorcin is a crystal at room temperature, but a small amount of it evaporates during heat curing, so care must be taken at the work site. Furthermore, residual unreacted resorcin after curing will adversely affect product performance. Therefore, conventionally, complicated and complicated operations have been performed to remove unreacted resorcin by extraction or other methods from the precursor prepolycondensate, but the effect is not sufficient. An object of the present invention is to produce a precursor prepolycondensate of resorcin and formaldehyde (hereinafter referred to as resorcin resin for the sake of simplicity) having an extremely low unreacted resorcin content and excellent fluidity.

  To achieve the above object, in the present invention, an aqueous solution of salts of resorcin and resorcin resin that inhibits water solubility (hereinafter referred to as a resorcinol water-soluble inhibitor) and an acid catalyst containing resorcin and formaldehyde in the presence of 2-butanone. After the lower reaction, the 2-butanone phase is separated, 2-butanone is distilled off, and the generated resorcin resin is heated to a molten state, and an inert gas is sent to the resin surface with the unreacted resorcin. A sufficient amount of unreacted resorcin was removed from the system by discharging it out of the system to produce a resorcin resin with a reduced amount of unreacted resorcin.

  Conventionally, the content of unreacted resorcin in the resorcin resin was 13% or more, but according to the present invention, the content can be reduced to 7% or less. For this reason, the environment at the work site where the resorcin resin is used is remarkably improved, and the performance of the resorcin resin is also improved.

BEST MODE FOR CARRYING OUT THE INVENTION

  The present invention will be described in detail below. When resorcinol and formaldehyde are reacted in the presence of an aqueous solution of resorcinol and 2-butanone in the presence of an acidic catalyst, the reaction solution is divided into two phases. The reaction proceeds mainly in the aqueous phase. Although the molecular weight of the reaction product gradually increases, the product having a relatively large molecular weight shifts to the 2-butanone phase because of the presence of the resorcinol water-soluble inhibitor in the aqueous phase. After the reaction, a considerable amount of unreacted resorcin remains in the aqueous phase. However, the generated molecules of each molecular weight are distributed in both phases with a certain distribution ratio depending on the kind and amount of the resorcinol water-soluble inhibitor. Thus, there is a molecular weight distribution in both phases. As a result of the analysis, it is known that an unreactable amount of unreacted resorcin has been transferred to the 2-butanone phase. Accordingly, since this method alone cannot sufficiently remove unreacted resorcin, a method such as washing the 2-butanone phase with pure water has been adopted, but the effect is not sufficient and the process is complicated. Therefore, it is difficult to recover 2-butanone.

  On the other hand, when the resorcin resin is heated to a molten state, the unreacted resorcin contained in the resorcin resin has some volatility, so that it evaporates somewhat. However, it does not evaporate to the extent that it can be recovered by distillation. The resorcin molecule has a very short flight distance even in reduced-pressure air, so it is difficult to take it out of the system even under reduced-pressure distillation. If the heating temperature is extremely raised, there is a slight effect, but the resin may be oxidized and deteriorated. In addition, since the partial pressure is low, a steam distillation method in which water is added for distillation is conceivable, but in practice, a ridiculous result cannot be obtained.

  In the present invention, in order to improve this situation, a gas that does not oxidize resorcin is sent to the heated resin surface after distilling off 2-butanone, and the gas is discharged out of the system, so that the gas near the resin surface is discharged. It was found that it is possible to forcibly induce resorcinol out of the system. In this case, the resorcinol vaporized adheres as crystals to a relatively low temperature vessel wall outside the system. By continuously sending the gas, it was possible to continuously separate only the unreacted resorcin from the resin. Crystallized resorcin is so pure that it can be reused. Usable gases include air, nitrogen gas, carbon dioxide gas, water vapor, and inert gases such as argon, but air is the cheapest and easiest to use. Oxidation of the resin with air is acceptable if the temperature of the resin is kept below 160 ° C. Accordingly, the melting temperature of the resin is preferably maintained at a temperature from about 120 ° C. to about 160 ° C.

  In general, in order to ensure the fluidity of resorcin resin, a reaction product in which two to three resorcins are bound in one molecule, in other words, a resin containing a large amount of resorcin dimer or trimer. Is desirable. That is, in Table 1, increasing the value of D with n = 2 or n = 3 is effective for increasing the fluidity of the reaction product. Therefore, in the present invention, the type and amount of the resorcinol water-soluble inhibitor may be selected for that purpose. In the method of the present invention, the increase in the average molecular weight of the resorcin resin is suppressed by the presence of the water-soluble resorcin inhibitor during the reaction.

  The resorcinol water-soluble inhibitor referred to in the present invention is a kind of salt that adjusts the molecular weight of the resorcinol formaldehyde reaction product. A salt is a general term for compounds formed in a form in which a cation and an anion neutralize an electric charge, but a resorcinol water-soluble inhibitor in the present invention is a hydratability that is higher than a chloride ion in a Hofmeister permutation. In the same permutation, the cation is a salt that is a cation exhibiting hydration properties when it is monovalent or higher, and when it is divalent, it is a cation that exhibits hydration properties higher than calcium ion. The Hoffmeister permutation is a permutation indicating the degree of hydration of each ion announced by Hofmeister in 1888. This is shown in Chemical Formula 1 below.

  Specifically, sodium citrate, calcium citrate, sodium tartrate, calcium tartrate, sodium acetate, calcium acetate, sodium chloride, magnesium chloride, calcium chloride and the like can be used as a resorcinol water-soluble inhibitor in the present invention. Among them, calcium chloride is the most excellent resorcinol water-soluble inhibitor in the present invention because of its effectiveness and easy handling.

  In the present invention, when the amount of the resorcin-soluble inhibitor is calculated as an anhydrous salt, the concentration of the resorcin-soluble inhibitor as an aqueous solution is adjusted between 15% and 40%, preferably between 20% and 30%. That's fine. The amount of resorcin at the start of the reaction may be set near the maximum concentration at which resorcin is dissolved in the aqueous solution. For example, 100 g of a 24% calcium chloride aqueous solution dissolves about 8.2 g of resorcin at normal temperature. When the concentration of calcium chloride is higher than 24%, resorcin tends to precipitate. If there is little resorcinol water-soluble inhibitor, it will not be effective, and if it is too much, resorcin itself will not dissolve even if the temperature is raised.

The amount of 2-butanone is set to be between 1/10 and 10 times the amount of resorcin. Usually between 2 and 6 times the amount.
The amount of formaldehyde in the reaction of the present invention is between 0.05 mol and 0.8 mol, preferably between 0.2 mol and 0.7 mol, per 1.0 mol of resorcin.

  Either an inorganic acid or an organic acid can be used as the reaction catalyst. Of these, hydrochloric acid is the easiest to use. The amount of the reaction catalyst is between 0.0001 mol and 0.1 mol, preferably between 0.005 and 0.03 mol, relative to 1.0 mol of resorcin. If the amount of the catalyst is small, the reaction takes time. If the amount is too large, the reaction rate increases and the molecular weight is not sufficiently adjusted.

  The reaction temperature can be 0 ° C. or higher and 75 ° C. or lower under atmospheric pressure, but is preferably 10 ° C. or higher and 60 ° C. or lower, more preferably a temperature between about normal temperature and 50 ° C.

  Next, the present invention will be described in more detail by way of examples of the present invention. However, the present examples show typical examples of the present invention, and various change applications exist within the scope of the present invention. Is not to deny.

  78.75 g of resorcin was dissolved in 332.25 g of water, and 213.80 g of calcium chloride was added. Since heat of dissolution occurred, it was cooled to 22 ° C. Resorcin was completely dissolved and no precipitate was present. Further, 300.8 g of 2-butanone was added. The reaction solution became two-phase. Next, 9.0 g of 3.6% hydrochloric acid was added and 33.0 g of 37% formaldehyde water was added dropwise at a time while stirring well. After stirring for about 4 hours, the reaction was stopped by adding to the reaction solution with dilute aqueous sodium hydroxide until pH 4.0. The entire amount of the reaction solution was transferred to a separatory funnel, and the 2-butanone phase was collected and transferred to a type flask having an inner diameter of the neck of about 27 mm. At this time, the amount of unreacted resorcin in the reaction product resin is G.P. P. C analysis showed 11.5%.

  An eggplant-shaped flask was attached to the rotary evaporator via a backflow prevention trap. At this time, a thick paper with a thickness of about 1 mm, a width of about 5 mm, and a length of about 30 mm is sandwiched between the neck of the flask that forms the trap, and a gap is created so that external air can flow in, and the evaporator is fixed. The vacuum exhaust was performed. In the fitting of the sliding portion, the trap was convex and the formed mold was concave. Therefore, it was observed that the air flowing from the gap of the sliding portion collided with the 2-butanone solution and the solution surface was undulated. The introduced air was reversed at the surface of the contents of the flask flask and was exhausted from the aspirator to the outside via the trap and the evaporator cooling section. In this state, most 2-butanone was distilled off by heating in a water bath. Next, the water bath is replaced with an oil bath, and the temperature of the oil bath is set to 140 ° C. and the air is blown in the same manner. Heated. After a while, the unreacted resorcin molecule began to evaporate, and pure white resorcin crystals were deposited on the trap and the evaporator wall. Three hours later, this operation was terminated, and the resin in the eggplant flask was weighed to be 80.5 g. G. P. As a result of C analysis, the amount of unreacted resorcin in the resin was 5.46%.

  Resorcin resin is a main component of an extremely useful adhesive because it dissolves well in alkaline water and does not require the use of an organic flammable solvent, is a relatively harmless resin, and has a high curing rate. Currently, it is widely used to bond various tire cords and rubber used in automobile tires. Since unreacted resorcin is removed by the present invention, the working environment is improved and the performance of the product is improved. It is certain that the present invention will develop as an extremely useful technology in the industry.

Claims (2)

  Resorcin and an aqueous solution of a water-soluble inhibitor of resorcin, which is a salt that restricts the water-solubility of a resorcin resin, and an acid catalyst and 2-butanone are reacted with resorcin and formaldehyde, and then the 2-butanone phase is separated to give 2- Butanone is distilled off, the produced resorcin resin is heated to a molten state, an inert gas is sent to the resin surface and discharged together with unreacted resorcin, and a sufficient amount of unresorcinated resin is discharged. A new production method of resorcin resin that reduces the amount of unreacted resorcin by eliminating reactive resorcin outside the system.   In the same permutation, the resorcin-soluble water-soluble inhibitor is monovalent or higher in the same permutation as an anion having a hydration property greater than or equal to the chloride ion. 2. A new method for producing a resorcin resin having a reduced amount of unreacted resorcin according to claim 1, which is a salt comprising ions.