JP2007100058A - Method for reducing unreacted resorcine in resorcine resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a resorcine resin with reduced content of unreacted resorcine and excellent in flowability. <P>SOLUTION: The invention relates to the method for reducing amount of the unreacted resorcine comprising heating the resorcine resin to a molten state and removing sufficient amount of the vaporized unreacted resorcine to outside by feeding an inert gas to the surface of the resorcine resin and discharging the gas with the unreacted resorcine to outside of the system. The invention relates to the method for reducing amount of the unreacted resorcine which comprises following steps for improving efficiency, a dividing step to divide the resorcin resin into a comparatively high molecular weight component and a comparatively low molecular weight component and then heating the low molecular weight component to a molten state and removing the vaporized unreacted resorcine to outside by feeding an inert gas to the surface of the resorcine to remove sufficient amount of the unreacted resorcine and joining it with the high molecular weight polymer component. <P>COPYRIGHT: (C)2007,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 resorcin and formaldehyde, followed by heating and curing at the point of use. Precursor prepolycondensates 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.

Number 1

D = nP ^(n-1.0) (1.0-P) ^2.0

  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.

Problems to be solved by the invention

  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.

Means for solving the problem

In order to achieve the above object, in the present invention, the resorcin resin is heated to a molten state, an inert gas to the resorcin resin is sent to the surface of the resin, and discharged together with unreacted resorcin. A sufficient amount of unreacted resorcin was excluded from the system to produce a resorcin resin with a reduced amount of unreacted resorcin.
Furthermore, for the purpose of improving efficiency, the resorcin resin is divided into a high molecular weight component having a relatively high molecular weight and a low molecular weight component having a relatively low molecular weight, and the low molecular weight component is heated to a molten state. An inert gas with respect to the resorcin resin is sent to the system and further discharged together with the unreacted resorcin to remove a sufficient amount of the unreacted resorcin from the system, and then combined with the high molecular weight component. Thus, a resorcin resin with a reduced amount of unreacted resorcin was produced.

  Resolving method is a method of reacting resorcin and formaldehyde in water using an acidic catalyst in water in the presence of a resorcin resin precipitation agent to precipitate a relatively high molecular weight component, and then extracting a relatively low molecular weight component from the aqueous phase by organic solvent extraction. Is the way to get.

  Further, by reacting the low molecular weight component with the ketones and then removing the unreacted resorcin as described above, the unreacted resorcin could be reduced to some extent. It was also found that the heat resistance of the obtained resin was improved.

The invention's effect

  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 the resorcin resin is heated to a molten state, the unreacted resorcin contained in the resorcin resin has a little volatility, so that it evaporates somewhat. However, it does not evaporate to the extent that it can be recovered by distillation. And since the flight distance of resorcin molecules in the air is very short, it is difficult to extract out of the system by vacuum 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 and the resorcin vaporized near the resin surface is forced out of the system by discharging the gas out of the system. I found that it was possible to guide. 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 order to further improve the efficiency of the method of the present invention, it is still effective if the resorcin resin is divided into a relatively high molecular weight component and a relatively low molecular weight component in advance, and the above method is applied to the obtained low molecular weight component. is there. The reason is considered as follows. Since most of the unreacted resorcin is transferred to the low molecular component by the splitting treatment, the proportion of the unreacted resorcin in the low molecular component is higher than that of the original resin. Since the evaporation amount of resorcin per unit time depends on the proportion of unreacted resorcin in the resin, the amount of evaporation of unreacted resorcin inevitably increases when the low molecular component is heated. The low molecular component has a lower viscosity than the high molecular component. Therefore, the diffusion movement of unreacted resorcin in the resin is facilitated. In addition, a new resin surface can be easily formed by agitation, rotation, or thermal motion by external force in the heated and melted state. Since the amount of evaporation increases due to various factors, unreacted resorcin can be recovered quickly.

  Next, the method of the division process will be described. 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 resorcin resin precipitation agent (hereinafter referred to as precipitation agent) may be selected depending on the purpose.

  In the split treatment method of the present invention, an increase in the average molecular weight of the resorcin resin is suppressed by the presence of the precipitant during the reaction. Although this point is slightly more complicated than the other division methods, it is a great advantage.

  The precipitant referred to in the present invention is a certain 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 electric charge, but a precipitant in the present invention is an anion whose hydration is higher than that of a chloride ion in the Hofmeister permutation. In the same permutation, the salt is a cation that exhibits hydration properties that are higher than sodium ions, and that that is more than calcium ions in the case of divalent ions. 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 precipitant in the present invention. Among them, calcium chloride is the most excellent precipitation agent in the present invention because of its effect and easy handling.

When resorcin and formaldehyde are reacted in water, as shown in Table 1, products from low to high molecular weight are obtained with a certain probability according to the quantitative ratio of resorcin and formaldehyde. However, when a precipitant is present, the solubility in water rapidly decreases in the process of the product becoming a polymer, so when a certain amount of product with a certain degree of condensation proceeds, the product molecule There is a tendency to precipitate. In that case, the product of each degree of condensation has a certain solubility in water depending on the concentration of the precipitating agent, but the solubility is different when there is a large amount of homologs when it is present alone and is quite complex. Therefore, it is not possible to make a general decision. Also, the precipitate does not have a distinctly clear line consisting only of a product having a certain molecular weight or more, but has a pattern of molecular weight distribution including a small amount of unreacted resorcin. However, the proportion of the high molecular weight component is significantly higher than that of the resin in the case of no splitting treatment. However, it is also certain that the average molecular weight of the whole resin tends to be lower than the case where no precipitant is present due to the use of the precipitant. In this case, it is reasonable to think that the reaction rate of the deposited high molecular weight component and formaldehyde is much slower than the reaction rate of unreacted resorcin or low molecular weight components still remaining in water. Therefore, there is no growth of the precipitated resin, that is, no increase in molecular weight.
Next, when referring to the low molecular weight component remaining in the mother liquor, there is no clear line that it consists only of a product having a certain molecular weight or less. It has a molecular weight distribution with a certain pattern. However, the proportion of unreacted resorcin in the low molecular weight component is increased in each stage compared to the proportion of unreacted resorcin in the resin when the splitting treatment is not performed.

  In the present invention, when the amount of the precipitating agent is calculated as an anhydrous salt, the concentration of the precipitating agent as an aqueous solution may be adjusted between 15% and 40%, preferably between 20% and 30%. 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 the amount of the precipitating agent is small, there is no effect. If the amount is too large, resorcin itself does not dissolve even when the temperature is raised.

  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. If the amount of formaldehyde is small, the amount of precipitation is small, and if it is too large, the production of high molecular weight components increases.

  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. This is because it takes a certain time until the reaction product precipitates after reaching the saturated concentration.

  The reaction temperature can be 0 ° C. or higher and 100 ° C. or lower under atmospheric pressure, but preferably 0 ° C. or higher and 70 ° C. or lower. Further preferred is a temperature near room temperature. If the temperature is low, the resorcin may not dissolve in the presence of the precipitant. When the temperature is high, not only the reaction rate becomes too high, but also the high molecular weight component may not be precipitated even if a precipitant is present.

  Since the precipitated high molecular weight component is a free-flowing precipitate, the reaction mother liquor in which the low molecular weight component is dissolved can be sufficiently separated by a method such as compression filtration or suction filtration. However, since the mother liquor cannot be completely removed, low molecular weight components contained in a small amount of mother liquor that cannot be removed remain on the high molecular weight component side, but this is unavoidable.

  The precipitating agent remains in the high molecular weight component. If this becomes a problem depending on the application, the precipitation agent may be removed by a generally known method. For example, a selective solvent method using a solvent that dissolves the reaction product but not a precipitation agent, an ion exchange method, an ion exchange membrane electrodialysis method, a precipitation method in which a reagent that reacts with the cation of the precipitation agent and insolubilizes is added. is there. When the precipitating agent is calcium chloride, an organic solvent such as 2-butanone, methyl isobutyl ketone, tetrahydrofuran, or ethyl acetate can be used as a selective solvent method.

  Low molecular weight components are dissolved in the reaction mother liquor separated by filtration. Low molecular weight components can be extracted from the reaction mother liquor by organic solvent extraction. For extraction, an organic solvent such as 2-butanone, methyl isobutyl ketone, tetrahydrofuran, or ethyl acetate can be used. Since the extracted low molecular weight component solution does not contain a precipitant, it is very convenient. A low molecular weight component can be obtained by distilling off the organic solvent by distillation. This completes the division process.

  The process proceeds to a step of removing unreacted resorcin from the low molecular weight component, but it is also possible to react the low molecular weight component and ketones before that. Resorcin or resorcin resin easily reacts with ketones under an acidic catalyst. In this case, since ketones react as a bifunctional compound like formaldehyde, excessive reaction is not preferable because long molecules are formed and the solubility in water is lowered. If the resorcin resin has a large amount of high molecular weight components, the solubility in water similarly decreases, which is not preferable. In that sense, ketones are suitable for the purpose of reacting with low molecular weight components. It is not preferable to react for a long time because there is a similar danger. When 2-butanone is selected as the ketone, it is sufficient from experience that a low molecular weight component is dissolved in 2-butanone and then reacted at the boiling temperature of 2-butanone for about 2 hours. In this case, since the color of the solution changes from red yellow to green yellow, the progress of the reaction can be determined. By reacting the low molecular weight component and the ketones, the ketones also react with the unreacted resorcin, which is advantageous for reducing the unreacted resorcin. Also, the heat resistance of the resin is somewhat improved.

  Examples of ketones that can be used include acetone, 2-butanone, diethyl ketone, methyl butyl ketone, and methyl isobutyl ketone. The reactivity becomes weaker as the molecular weight of the ketones increases. As the acidic catalyst, an acidic compound similar to the compound used for the reaction of resorcin and formaldehyde can be used. The amount is between 0.0001 mol and 0.1 mol, preferably between 0.005 mol and 0.03 mol, relative to 1.0 mol resorcin.

Next, after neutralizing the low molecular weight component, unreacted resorcin is removed by the method described above. The obtained low molecular weight component is dissolved in an organic solvent such as neutral 2-butanone, methyl isobutyl ketone, tetrahydrofuran, ethyl acetate, etc., and combined with the organic solvent solution of the high molecular weight component separately prepared as described above, and an appropriate amount of water. And a high concentration aqueous solution of resorcin resin with reduced unreacted resorcin can be obtained by distilling off the organic solvent and considerable water by distillation. The concentration of the aqueous solution can be 40% or more. A small amount of a high molecular weight component may be deposited in this solution with the standing time, but this is practically acceptable.
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.

Embodiment of the Invention

  46.70 g of resorcin was dissolved in 421.10 g of water, and 138.00 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. Next, 21.50 g of 37% formaldehyde water was added dropwise at a time while adding 11.00 g of 3.6% hydrochloric acid and stirring well. The mixture was stirred for about 1 hour with a magnetic stirrer, and the stirring was stopped and left at room temperature of 22 ° C. for about 12 hours. About 30 minutes after the addition of formaldehyde water, a white precipitate of a high molecular weight component started to precipitate. After about 12 hours, a large amount of white precipitate was formed in the reaction solution. This precipitate did not cling to the stir bar and did not stick. In order to neutralize hydrochloric acid in the reaction solution, an equimolar amount of 3% aqueous sodium hydroxide solution was added dropwise with stirring. The pH of the reaction solution increased from 1 to 4.

  Next, the reaction solution was subjected to suction filtration. The precipitate was 91.75 g in a wet state. 124.20 g of 2-butanone was added to the precipitate and dissolved. The liquid showed a 2-butanone phase in the upper layer and an aqueous phase in the lower layer. The upper 2-butanone phase was separated with a separatory funnel. The 2-butanone phase was 154.75 g and the aqueous phase was 43.95 g. As a result of measuring the concentration of the 2-butanone phase, it was 25.37%, so the solid content of the high molecular weight component was 39.26 g.

  On the other hand, the filtrate of suction filtration was 536.45 g. In a separatory funnel, 150.00 g of 2-butanone was added to this filtrate and shaken well to extract the low molecular weight components dissolved therein. The fraction of 2-butanone phase was 143.10 g. As a result of measuring the concentration, it was 8.10%, so the solid content of the low molecular weight component was 11.69 g.

この結果から低分子量成分中には多量の未反応レゾルシンが存在する事が分かった。Next, in order to know what the molecular weight distribution of the high molecular weight component and the low molecular weight component is. P. C analysis was performed. The result was as follows. Each data represents the percentage of each peak area. Monomer means unreacted resorcin.

From this result, it was found that a large amount of unreacted resorcin was present in the low molecular weight component.

  The 2-butanone solution of the low molecular weight component was transferred to a 300 ml-shaped flask and 1 g of 3.6% hydrochloric acid was added, and a low temperature component and 2-butanone were reacted by heating for 2 hours while refluxing. . The color of the liquid changed from reddish yellow to light greenish yellow. Next, a 3% aqueous solution of caustic soda corresponding to the amount of hydrochloric acid in the low molecular component was added to neutralize the solution to pH 4. This reaction solution was dissolved in G.P. P. When subjected to C analysis, the amount of unreacted resorcin was 55.85%. It was found that unreacted resorcin decreased somewhat.

  An eggplant-shaped flask was attached to the rotary evaporator via a backflow prevention trap. At this time, a cardboard is fixed on the neck sliding part of the trap flask, and the evaporator is connected to the aspirator to reduce the pressure. Observed. 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 the pure white resorcin crystals adhered to the walls of the trap and the evaporator. After 3 hours, this operation was terminated, and the low molecular weight component in the eggplant flask was weighed to be 6.04 g. It can be seen that a significant amount of unreacted resorcin has been removed. G. P. As a result of C analysis, the amount of unreacted resorcin was 20.16%.

  The low molecular weight component was dissolved in 30.80 g of tetrahydrofuran, combined with the aforementioned high molecular weight component 2-butanone solution, and 75.00 g of water was added and distilled. The liquid in the flask made transparent by distilling off the organic solvent and considerable water became transparent. At this point, the distillation was stopped. 92.5 g of a resorcin resin solution having a concentration of 42.52% was obtained. This resin is referred to as G.I. P. As a result of C analysis, the amount of unreacted resorcin was 6.34%.

  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 (5)

  The resorcin resin is heated to a molten state, a gas inert to the resorcin resin is sent to the resin surface, and a sufficient amount of unreacted resorcin is discharged outside the system together with unreacted resorcin. A method for producing a resorcin resin in which the amount of unreacted resorcin is reduced.   The resorcin resin is divided into a high molecular weight component having a relatively high molecular weight and a low molecular weight component having a relatively low molecular weight, and the low molecular weight component is heated to a molten state, and the surface of the component is inert to the resorcin resin. A sufficient amount of unreacted resorcin is removed from the system by removing the sufficient amount of unreacted resorcin from the system. Method for producing reduced resorcin resin.   In the presence of resorcin resin precipitants, a process of reacting resorcin and formaldehyde in water using an acidic catalyst to precipitate a relatively high molecular weight component and extracting a relatively low molecular weight component from the aqueous phase by organic solvent extraction. A method for reducing unreacted resorcin in the resorcin resin according to claim 1.   In the same permutation, the resorcin resin precipitant in the Hofmeister permutation is a cation that exhibits a hydration property greater than sodium ion in the same permutation, and a hydration property greater than calcium ion in the divalent case. The method for producing a resorcin resin with a reduced amount of unreacted resorcin according to claim 3, which is a salt comprising:   The low molecular weight component is dissolved in an organic solvent and reacted with ketones in the presence of an acidic catalyst, and then the solvent is distilled off and heated to a molten state. A gas inert to the resorcin resin is formed on the surface of the low molecular component. 3. The method for producing a resorcin resin with a reduced amount of unreacted resorcin according to claim 2, wherein a sufficient amount of unreacted resorcin is removed from the system by feeding and discharging to the outside of the system together with unreacted resorcin.