JP2006169486A - Process for production of resorcin resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for production of a resorcin resin with very low content of unreacted resorcin and excellent in fluidity. <P>SOLUTION: The process for production is made producible the resorcin resin by a reaction of dissolved resorcin in a good solubility solvent with solubility parameters of 9.0 or over, formaldehyde and an acidic catalyst, addition of a solvent with poor solubility of resorcin with solubility parameters of 9.0 or less, compatible with the afore mentioned good solubility solvent at a larger volume to the afore mentioned good solubility solvent, and having boiling points higher than the afore mentioned good solubility solvent, followed by removal of almost all the solvent with good solubility of resorcin by a distillation method, then transfer of the residual reaction solution in the other vessel while still hot and isolation of the precipitated resin in the reaction vessel to give the resorcin resin with excellent fluidity and small content of the unaltered resorcin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a resorcin resin. Specifically, the present invention relates to a method for producing a novolac type resorcin resin that is a linear polycondensate of resorcin and formaldehyde.

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 heat reaction curing at the point of use. A precursor pre-polycondensate that is a type resorcin formaldehyde resin may be used. It is particularly useful as a component of a tire cord / rubber adhesive.
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

この表の番号１，２，３、４はＰとｎの値を変えた場合の上式によるＤの計算結果を示す。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 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.

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 crystallized at room temperature, but it is very sublimable and vaporizes during heat curing, so care must be taken at the work site. Furthermore, the possibility that unreacted resorcinol remains after curing cannot be wiped out, and the product performance is adversely affected. Accordingly, a resorcin resin having a low unreacted resorcin content has been desired. Conventionally, an operation of removing unreacted resorcin from the precursor prepolycondensate by extraction or other methods has been performed, but the effect is not sufficient. In general, in order to ensure fluidity, it is desirable to obtain a reaction product in which two to three resorcins are bound in one molecule, in other words, a large amount of resorcin dimer or trimer. . 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. However, the physical and chemical properties of these reaction products are very close to those of the resorcin body. Therefore, it is extremely difficult to isolate only resorcin from the resin. That is, the amount of resorcin dimer and trimer tends to decrease. In this way, the purpose cannot be achieved.
The present invention provides a method for producing a resorcin resin having an extremely low unreacted resorcin content and excellent fluidity.

  In order to achieve the above object, in the present invention, resorcin is dissolved in a good solvent of resorcin having a solubility parameter of 9.0 or more, and reacted by adding formaldehyde and an acidic catalyst, and has a boiling point higher than that of the good solvent. Add a larger amount of the poor solvent of resorcin that is compatible with the good solvent to 9.0 or less than the good solvent, then remove most of the good solvent by distillation, and transfer the remaining solution to another container when hot. The content of unreacted resorcin in the resorcin resin was reduced by removing the resin precipitated in the reaction vessel.

  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 6% 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

  In the present invention, formaldehyde water or paraformaldehyde is used as formaldehyde.

  In the present invention, the acidic catalyst refers to an inorganic acid or an organic acid. Hydrochloric acid is most preferably used for inorganic acids, and p-toluenesulfonic acid is most preferably used for organic acids.

  In the present invention, the good solvent for resorcin refers to a solvent that dissolves resorcin in a large amount at room temperature. The solubility parameter, which is the physical constant of these solvents, is often 9.0 or more. Specifically, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, 1-butanol and tert-butanol, ethers such as diethyl ether, dioxane and tetrahydrofuran And esters such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate. The good solvent should be used twice or more, preferably three times or more the resorcin resin.

  The poor solvent for resorcin of the present invention refers to a solvent that hardly dissolves resorcin at room temperature but dissolves to some extent at high temperature. The solubility parameter of such a solvent is often 9.0 or less. Specifically, aromatic hydrocarbons such as benzene, toluene and xylene are preferably used. The poor solvent may be added in an amount of about twice or more, preferably three times or more that of the good solvent. It is possible to use a mixed solvent of a good solvent and a poor solvent for the purpose of increasing the reaction temperature when dissolving resorcin at first.

  Next, the reason why unreacted resorcin can be reduced according to the method of the present invention will be described. It is possible to extract unreacted resorcin from the resorcin resin using a poor solvent. The poor solvent is excellent as an extraction solvent because it selectively dissolves resorcin and does not dissolve much of the multimeric product of resorcin dimer or higher. However, the amount of unreacted resorcin extracted by one extraction operation is extremely small. Therefore, many operations and a large amount of poor solvent are required to reduce the content of unreacted resorcin to a satisfactory level. This is because the poor solvent is not absorbed into the resorcin resin, and the unreacted resorcin is diffused and transferred from the inside of the resin to the resin surface in contact with the poor solvent. It is no exaggeration to say that the poor solvent extracts only unreacted resorcin present in the vicinity of the resin surface. Therefore, the amount of unreacted resorcin extracted is very small.

  In the present invention, when the resorcin resin is produced, it is dissolved in a good solvent. As the proportion of good solvent decreases as a poor solvent is added to the reaction solution and the good solvent is discharged out of the system by distillation, the polymer component having a higher molecular weight in the produced resin sequentially precipitates in the reaction vessel. Come. It can be said that the method of the present invention is a distillation fractional precipitation method. When the good solvent is almost discharged, only low molecular components of the produced resin and unreacted resorcin are contained in the solvent. If distillation is continued to near the boiling point of the poor solvent, the only component dissolved in the solvent is unreacted resorcinol. Therefore, if the solution is transferred to another container while the resorcin crystals are not precipitated, and the total amount of the precipitated resin in the reaction container is taken out, a resin with an extremely small amount of unreacted resorcin can be obtained. In order to take out the resin, it may be dissolved in a good solvent or dissolved in alkaline water.

Since resorcin itself dissolves in a poor solvent at high temperatures, the amount of resorcin in the solvent does not change. Thus, a large amount of unreacted resorcin can be taken into the solvent. The purity of the unreacted resorcin improves as the temperature at the end of distillation approaches the boiling point of the poor solvent. However, it takes a long time for the distillation temperature to approach the boiling point of the poor solvent. In addition, a large amount of poor solvent is required. As a practical solution processing method, it is sufficiently effective to set the end point temperature of distillation about 0.2 ° C. lower than the boiling point of the poor solvent.
Hereinafter, the present invention will be described in detail by way of examples. However, the description of the examples does not limit the present invention.

  9.31 g of resorcin was dissolved in a mixed solvent consisting of 40.00 g of tetrahydrofuran and 20.00 g of toluene, and 1.08 g of 3.6% hydrochloric acid and 4.30 g of 37% formaldehyde water were added and heated at reflux for 6 hours. Next, 180 ml of toluene was added and distillation was started. The distillation was stopped when the distillation temperature reached 11.4 ° C. While the reaction solution was still hot, the solution was separated by a gradient method. The amount of the separated reaction liquid was 57.92 g. The amount of the resin deposited on the bottom was 8.85 g. The resin was dissolved in 40 ml of methyl ethyl ketone, 40 ml of water and 1 ml of 28% ammonia water were added and distilled under reduced pressure while heating to give a 50% resorcin resin aqueous solution. The obtained resorcin resin was converted to G.P. P. It was measured by C (gel permeation chromatography) method. The content of unreacted resorcin was 3.25%. When the separated reaction solution was cooled, white crystals of unreacted resorcin were deposited.

Comparative Example 1

  19.62 g of resorcin is dissolved in 106.62 g of water, 1.13 g of 3.6% hydrochloric acid and 9.05 g of 37% formaldehyde water are added and left at room temperature for 24 hours, and 3.03 g of 3.0% aqueous sodium hydroxide solution is added. Hydrochloric acid was neutralized. p. H increased from 1 to 4. Water in the filtrate was removed by distillation, 120 ml of toluene was added, heated to the boiling point of toluene, and refluxed for about 2 hours. When the upper layer solution was separated from the resin by the gradient method and toluene in the liquid was distilled off, white crystals of resorcin appeared at the bottom of the container. When weighed, it was 0.18 g. The resin after extracting this resorcin is referred to as G.P. P. When analyzed by method C, the content of unreacted resorcinol was 13.3%.

  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 (1)

    Resorcin is dissolved in a good solvent of resorcin having a solubility parameter of 9.0 or more, and formaldehyde and an acidic catalyst are added and reacted, and a solubility parameter that has a boiling point higher than that of the good solvent and is compatible with the good solvent is 9. Resin that is deposited in the reaction vessel by adding the poor solvent of resorcin below 0 in a larger amount than the good solvent, then removing most of the good solvent by distillation, and transferring the remaining reaction solution to another vessel when hot. A method for producing a resorcin resin in which the content of unreacted resorcin is reduced.