JP5547417B2 - Method for producing resorcinol formaldehyde resin - Google Patents

Description

  The present invention relates to a method for producing a resorcin formaldehyde resin, and a resorcin formaldehyde resin produced by the method.

  Conventionally, resorcin formaldehyde resin has a fast curing speed, so it has been used for adhesives, plywood, laminated materials, surface coating materials, etc., and especially has excellent adhesion to rubber and fibers. It is used as

  When a resorcin formaldehyde resin is used as an adhesive, it is required that the resorcin formaldehyde resin has sufficient fluidity and is dissolved uniformly when a solvent coexists.

  Although it is conceivable to dilute with an organic solvent in order to impart fluidity, the use of an organic solvent is not preferable because it has a possibility of deteriorating the working environment and lowering the adhesive strength. There is also a method of dispersing in water with an anionic surfactant without using an organic solvent to make an adhesive (Patent Document 1), but there remains anxiety in terms of long-term stability of the aqueous dispersion.

  It is also empirically known that sufficient fluidity can be obtained by reducing the constituent ratio of the resorcin pentamer or more from the constituents of the polycondensate. Higher-order condensates of resorcin pentamer or higher are considered to lose fluidity because the ratio of the three-dimensional structure suddenly increases.

  However, when the reaction conditions are set gently so as to reduce the composition ratio of the resorcin pentamer or higher, the molecular weight distribution of the product simply shifts to the low molecular side, and usually unreacted resorcin (resorcin monomer) Body) concentration becomes high. It has been observed that when unreacted resorcin concentration increases, resorcin sublimates during drying when used as an adhesive. Since resorcin vapor is harmful to the human body, the unreacted resorcin concentration is required to be 15% by weight or less, preferably 10% by weight or less, more preferably 5% by weight or less. Moreover, it has been found that the less unreacted resorcin, the higher the adhesion.

  As a method for reducing unreacted resorcin, Patent Document 2 contains about 33% by weight of unreacted resorcin after completion of the reaction when 0.6 mole of formaldehyde is reacted with 1 mole of resorcin. When 8 mol of formaldehyde is reacted, about 20% by weight of unreacted resorcin is contained. Therefore, in order to reduce the unreacted resorcin content to 15% by weight or less, the degree of vacuum is 0.05 mmHg, 130%. It has been reported that unreacted resorcin is removed by sublimation at 0 ° C. Patent Document 3 reports that a continuous extractor was used using methyl isobutyl ketone as a solvent and water as an extractant, and the unreacted resorcin content was reduced to 5.5%. However, these methods are industrially disadvantageous, such as requiring vacuum distillation after completion of the reaction or requiring a long operation using a continuous extractor.

  In addition, if the reaction conditions are made violent in order to reduce the unreacted resorcin concentration, a high-order condensate of a pentamer or higher is generated in a large amount, which is not preferable.

  As a method for reducing both the resorcin monomer and the higher-order condensate of pentamer or more, Patent Document 4 describes the solubility of the resorcin multimer (particularly, pentamer or more having a three-dimensional structure) in the aqueous phase. In order to reduce the temperature, a method is described in which a salt is allowed to coexist in the reaction system, and an organic solvent having a solubility parameter of 7.0 to 12.5 for dissolving the resorcin formaldehyde resin is added. The peak area corresponding to the resorcin pentamer or more by gel permeation chromatography analysis of the resorcin formaldehyde resin obtained by this method is 30% to 55% with respect to the entire peak area, and corresponds to the resorcin monomer. The peak area is 3% to 9% with respect to the total peak area, and it has succeeded in reducing higher-order condensates of monomers and pentamers than conventional ones. However, in this method, it is necessary to heat in order to dissolve a large amount of salt, and an industrial problem that a step for removing the added salt is also required remains.

JP-A-57-167342 Japanese Patent Publication No.54-932 Japanese Patent Publication No.49-14550 International Publication No. 2005/035611 Pamphlet

  The present invention has been made based on the above background, and provides a method for producing a resorcin formaldehyde resin capable of reducing resorcin monomers and higher-order condensates of pentamers or more without adding a salt. provide.

  As a result of intensive studies to achieve the above object, the present inventors have conducted a heterogeneous reaction between resorcin and formaldehyde using phosphoric acid as a catalyst in a system in which water and esters form two phases. As a result, it was found that the higher-order condensate of resorcin monomer and pentamer or higher can be reduced without adding a salt, and the present invention has been completed.

  That is, the method for producing the resorcin formaldehyde resin of the present invention comprises a step of heterogeneously reacting resorcin and formaldehyde in the presence of esters, water, and 9 parts by mass or more of phosphoric acid with respect to 100 parts by mass of resorcin. It is characterized by having.

  According to the present invention, it is possible to reduce a resorcin monomer and a higher-order condensate of pentamer or higher without adding a salt. Therefore, it is not necessary to heat to dissolve the salt, the step of removing the salt can be omitted, and industrialization is easy.

  Further, it is possible to easily and safely efficiently obtain a resorcin formaldehyde resin in which the content of the resorcin monomer is 9% or less and the content of the higher-order condensate of the pentamer or more is 55% or less. By optimizing the conditions, a resorcin formaldehyde resin in which the content of resorcin monomer, which has been difficult to obtain in the past, is 3% or less and the content of higher-order condensate of pentamer or more is 20% or less. Can be obtained.

2 is a GPC chart of the product of Example 1. 2 is a GPC chart of the product of Example 18.

  The method for producing the resorcinol formaldehyde resin of the present invention requires resorcin and formaldehyde as raw materials, phosphoric acids as an acid catalyst, water as an aqueous phase, esters as an organic phase, and a heterogeneous state formed from these, for example, mechanically It has a step of synthesizing a condensate (resin) by advancing the reaction between resorcin and formaldehyde as a heterogeneous reaction (phase separation reaction) system by stirring and mixing with ultrasonic waves or the like. Next, for example, a water-insoluble organic solvent (for example, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, etc.) is added and mixed to dissolve the condensate, the mixing is stopped and the mixture is allowed to stand, and the organic phase (organic solvent phase) and The aqueous phase (phosphoric acid aqueous solution phase) is separated and the aqueous phase is removed to recover the phosphoric acids. On the other hand, the organic phase is washed with hot water and / or neutralized, and then the organic solvent is recovered by distillation. Formaldehyde resin can be produced. Since the production method of the present invention utilizes a heterogeneous reaction, the stirring efficiency is extremely important, and it is necessary to refine both phases in the reaction system to increase the surface area of the interface as much as possible. This facilitates the conversion of the resorcin monomer to the resin.

  Examples of formaldehyde used as a raw material include formalin and paraformaldehyde. Among these, formalin which is an aqueous solution in advance is preferable. The compounding molar ratio (F / Re) of formaldehyde (F) and resorcin (Re) is 0.33 or more, preferably 0.40 to 1.0, and more preferably 0.50 to 0.80. In the range of 0.50 to 0.80, a resorcin formaldehyde resin in which the resorcin monomer and the higher-order condensate of pentamer or more are further reduced can be produced in a high yield.

  The phosphoric acid used as the acid catalyst is preferably an aqueous solution type such as 89% by mass phosphoric acid, 85% by mass phosphoric acid, 75% by mass phosphoric acid, etc. Etc. may be used. The compounding quantity of phosphoric acid (pure substance) is 9 mass parts or more with respect to 100 mass parts of resorcinol, Preferably it is 30 mass parts or more, More preferably, it is 50-150 mass parts. If the amount of phosphoric acid (pure substance) is less than 9 parts by mass with respect to 100 parts by mass of resorcin, unreacted resorcin monomer increases, which is not preferable.

  Esters used in the present invention play an important role in forming a heterogeneous reaction field with water in the presence of formaldehyde, resorcin, and phosphoric acids.

  Specifically, for example, methyl formate, ethyl formate, propyl formate, butyl formate, isobutyl formate, isoamyl formate, hexyl formate, benzyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, allyl acetate, n-butyl acetate S-butyl acetate, isobutyl acetate, amyl acetate, isoamyl acetate, cyclohexyl acetate, benzyl acetate, methyl cyclohexyl acetate, 2-ethylhexyl acetate, methyl propionate, ethyl propionate, butyl propionate, isoamyl propionate, benzyl propionate, Methyl lactate, ethyl lactate, butyl lactate, methyl butyrate, ethyl butyrate, isopropyl butyrate, isoamyl butyrate, methyl acetoacetate, ethyl acetoacetate, allyl acetoacetate, ethyl isovalerate, isoamyl isovalerate, methyl benzoate Ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, benzyl benzoate, methyl salicylate, isoamyl salicylate, benzyl salicylate, methyl cinnamate, ethyl cinnamate, ethyl stearate, butyl stearate, amyl stearate , Monoesters such as γ-butyrolactone, methyl abietic acid, diethyl oxalate, dibutyl oxalate, diamyl oxalate, dimethyl malonate, diethyl malonate, diisopropyl malonate, diethyl tartrate, dibutyl tartrate, dibutyl maleate, maleic acid Diesters such as dioctyl, diethyl adipate, dioctyl adipate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, dibutyl sebacate, dioctyl sebacate, Examples include triesters such as triethyl enoate and tributyl citrate, tetraesters such as acetyl triethyl citrate and tributyl acetyl citrate, and carbonates such as dimethyl carbonate, diethyl carbonate, and diphenyl carbonate.

  Among these, in view of compatibility with water, those having no ether group and / or hydroxyl group in the molecule are preferable. Further, the content of resorcin monomer and higher-order condensation of resorcin pentamer or higher. In terms of sufficiently reducing the content of the product, ethyl acetate, n-butyl acetate, benzyl acetate, propyl formate, dimethyl malonate, diethyl malonate, diethyl oxalate, triethyl citrate, tributyl citrate, methyl benzoate, Diethyl carbonate and the like are preferable. Also, ethyl acetate, butyl acetate, etc. having a low boiling point are preferable in terms of industrially easy handling in the production process of resorcin formaldehyde resin and finally evaporating and removing the esters. The esters are not limited to the above examples, and can be used in solid form as long as they have the above characteristics and exhibit a liquid state at the time of reaction, and each may be used alone or in combination of two or more. .

  In order to carry out a heterogeneous reaction in the presence of these esters and water, generally 1.0 to 2000 parts by mass of esters are added to 100 parts by mass of water, preferably 20 to 1500 parts. It is 100 mass parts, More preferably, it is 100-1000 mass parts.

  The reaction temperature between resorcin and formaldehyde varies depending on the reaction conditions, but the reaction can be carried out even at a relatively low temperature. Generally, it is 0-100 degreeC or more, Preferably it is 0-40 degreeC, More preferably, it is 0-25 degreeC. In addition, as reaction time, although it changes with reaction temperature, the compounding quantity of phosphoric acid, etc., generally it is about 1 to 40 hours.

  The reaction environment is usually atmospheric pressure, but the reaction may be performed under pressure or reduced pressure as long as the heterogeneous reaction characteristic of the present invention is maintained. Under a pressure of 50 MPa, the reaction rate can be increased.

  When the production method of the present invention is used, the content of the resorcin monomer is 9% or less and the content of the higher-order condensate of the pentamer or more is 55% or less as measured by the area method of gel permeation chromatography analysis. Preferably, a resorcin formaldehyde resin having a resorcin monomer content of 3% or less and a high-order condensate content of pentamer or more of 20% or less can be produced. The resorcinol formaldehyde resin of the present invention has a weight average molecular weight (Mw) of 200 to 500 and a dispersion ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) by gel permeation chromatography analysis measurement. It is 1.3 or less, preferably 1.2 or less.

  Examples The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. “Part” and “%” mean “mass standard” unless otherwise specified.

  The characteristics of the novolac type phenol resin were confirmed by measuring the obtained aqueous solution of resorcin formaldehyde resin by the following test method.

(1) Resorcinol monomer (monomer), 2- to 4-mer and pentamer-and-more component content (area%)
By measuring the gel filtration chromatograph 8220 series build-up system (column: G2000HXL + G4000HXL, detector: RI, carrier: tetrahydrofuran 1 ml / min, column temperature 40 ° C.) manufactured by Tosoh Corporation, the area of each component relative to the total area of the molecular weight distribution can be determined. The content was measured by the area method expressed as a percentage.

(2) Weight average molecular weight (Mw), number average molecular weight (Mn), dispersity (Mw / Mn)
Using the same apparatus, the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of standard polystyrene were determined, and the degree of dispersion (Mw / Mn) was calculated.

<Example 1>
In a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 27.5 parts of resorcin (Re) was dissolved in 13.8 parts of pure water and 27.5 parts of butyl acetate, and then 89% phosphoric acid was added. 27.5 parts added, and 13.6 parts of 37% formalin (F) (molar basis: while maintaining the system temperature at 5 to 10 ° C. under a cloudy state (two-phase mixture) formed by stirring and mixing. F / Re = 0.67) was added dropwise over 30 minutes. Furthermore, after performing the condensation reaction at the same temperature for 15 hours, the reaction was stopped. In addition, the condensation reaction was sampled every 1 to 2 hours, measured by gel permeation chromatography analysis, and performed until the increase in molecular weight was confirmed to have almost reached equilibrium.

  Next, 55.0 parts of methyl isobutyl ketone (MIBK) was added with stirring and mixing to sufficiently dissolve the condensate. Further, 27.5 parts of pure water was added, stirring was stopped, and the contents were separated. The solution was allowed to stand and allowed to stand to separate into a MIBK solution layer and a phosphoric acid aqueous solution layer. Next, the phosphoric acid aqueous solution layer was removed, and the MIBK solution layer was washed with water several times to remove phosphoric acid. Thereafter, the contents were returned again into the reaction vessel, and the removal of MIBK by evaporation and the addition of pure water were repeated to obtain an aqueous solution of resorcin formaldehyde resin.

  The obtained aqueous solution of resorcinol formaldehyde resin was subjected to gel permeation chromatography analysis. A GPC chart of the product of Example 1 is shown in FIG.

  The yield of resorcin formaldehyde resin was 103% with respect to the amount of resorcin charged (mass basis). The yield of resorcinol formaldehyde resin here represents the resin solid content obtained by drying an aqueous solution of resorcinaldehyde formaldehyde resin at 140 ° C. for 5 hours in a vacuum dryer as a percentage of the charged amount (mass basis) of resorcinol. I made it.

<Examples 2 to 26, Comparative Examples 1 to 4>
Resorcinol formaldehyde resin was produced and analyzed in the same manner as in Example 1 except that the conditions shown in Tables 1 to 6 were changed. A GPC chart of the product of Example 18 is shown in FIG.

<Comparative Example 5>
In a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 88.7 parts of pure water, 57.0 parts of calcium chloride, and 24.6 parts of resorcin were dissolved at 60 ° C., 10 parts of methyl ethyl ketone, 0.3 part of 35% hydrochloric acid was added. While maintaining the reaction system at 50 ° C., 10.9 parts of 37% formalin was added dropwise over 45 minutes, and after completion of the addition, the reaction was further continued by stirring for 1 hour. Further, 0.9 part of 37% formalin was added dropwise over 45 minutes, and after completion of the addition, the reaction was further stirred for 1 hour. While maintaining the temperature of the reaction system, the mixture was left to separate into two layers, and the lower aqueous phase was removed. The organic phase is diluted with 33.3 parts of methyl ethyl ketone, 16.7 parts of pure water is added, and the reaction system is further stirred for 1 hour while maintaining the same temperature. After standing, the aqueous phase is separated into two layers. The sample was extracted to obtain a methyl ethyl ketone solution of resorcin formaldehyde resin.

  33.3 parts of methyl ethyl ketone was added to the resulting methyl ethyl ketone solution of resorcin formaldehyde resin, distilled and dehydrated at an azeotropic temperature, cooled to room temperature, and then treated by filtration. Further, an appropriate amount of pure water was added to the contents, followed by distillation and dehydration at an azeotropic temperature to obtain 49 parts of an aqueous solution of resorcin formaldehyde resin having a solid content of about 50%.

  The obtained resorcin formaldehyde resin was subjected to gel permeation chromatography analysis in the same manner as in Example 1, and the obtained results are shown in Table 6.

<Comparative Example 6>
Resorcin formaldehyde resin was produced and analyzed in the same manner as in Comparative Example 5 except that the conditions shown in Table 6 were changed.

<Comparative Example 7>
In a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 66.5 parts of pure water, 42.8 parts of calcium chloride, 15.8 parts of resorcin, and 0.18 part of 35% hydrochloric acid are dissolved at 70 ° C. I let you. While maintaining the reaction system at 50 ° C., 6.6 parts of 37% formalin was added dropwise over 5 hours, and after completion of the dropwise addition, the reaction was further stirred for 1 hour. The reaction system was cooled to room temperature and then filtered to remove the reaction mother liquor. Next, 100.0 parts of 39% calcium chloride aqueous solution was added to the reaction product and stirred at 50 ° C. for 1 hour. Thereafter, the unreacted resorcin was removed by immediately filtering and removing the washing solution.

  Further, the reaction product was dried under reduced pressure, dissolved in 60.0 parts of methyl ethyl ketone, and filtered to remove precipitated calcium chloride. Subsequently, an appropriate amount of pure water was added to the contents, followed by distillation and dehydration at an azeotropic temperature to obtain 30 parts of an aqueous solution of resorcin formaldehyde resin having a solid content of about 50%.

  The obtained resorcin formaldehyde resin was subjected to gel permeation chromatography analysis in the same manner as in Example 1, and the results obtained are shown in Table 7.

<Comparative Example 8>
Resorcin formaldehyde resin was produced and analyzed in the same manner as in Comparative Example 7 except that the conditions shown in Table 7 were changed.

<Comparative Example 9>
In a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 72 parts of pure water and 98.3 parts of resorcin were placed and dissolved at 60 ° C., and then 37% formalin 38.0 with stirring at 105 ° C. The portion was added dropwise over 30 minutes and stirring was continued for another 6 hours. Next, 208 parts of toluene was added and the temperature was raised to 90 ° C., followed by concentration while raising the temperature to 105 ° C. while distilling off water by azeotropic distillation. The mixture was stirred for 60 minutes while maintaining the temperature, allowed to stand for 10 minutes to separate the toluene phase and the aqueous phase, and then 193 parts of the toluene phase from which the monomer and the like were extracted by decantation was removed. Thereafter, 200 parts of toluene was added and the same extraction treatment was repeated twice, and then toluene was distilled off by distillation under reduced pressure. Thereafter, pure water was added to the system to obtain 180 parts of an aqueous solution of resorcin formaldehyde resin having a solid content of about 50%.

  The obtained resorcin formaldehyde resin was subjected to gel permeation chromatography analysis in the same manner as in Example 1, and the results obtained are shown in Table 7.

Claims (4)

  A process for producing a resorcin formaldehyde resin, comprising a step of heterogeneously reacting resorcin and formaldehyde in the presence of esters, water, and phosphoric acids of 9 parts by mass or more with respect to 100 parts by mass of resorcin .   The method for producing a resorcinol formaldehyde resin according to claim 1, wherein the esters do not have an ether group and / or a hydroxyl group in the molecule.   The ester is at least one selected from ethyl acetate, n-butyl acetate, benzyl acetate, propyl formate, dimethyl malonate, diethyl malonate, diethyl oxalate, triethyl citrate, tributyl citrate, methyl benzoate, and diethyl carbonate. The method for producing a resorcinol formaldehyde resin according to claim 1 or 2, wherein: The method for producing a resorcinol formaldehyde resin according to any one of claims 1 to 3 , wherein the amount of formaldehyde is 0.50 to 0.80 mol per mol of resorcin.

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