JP2011094055A - Method for producing phenol resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a resol-type phenol resin, which has excellent water-dilutability and is reduced in the amount of remaining monomer. <P>SOLUTION: First, a reaction product (α) is obtained by reacting formaldehyde (F) and an alkanone (A) in a ratio that the molar ratio (formaldehyde(F)/alkanone(A)) of formaldehyde (F) to alkanone (A) is 3/1 to 8/1. Then, the reaction product (α), phenols (P) and formaldehyde (F') are reacted in the presence of an alkali catalyst in a ratio that the mass ratio (reaction product (α)/phenols (P)/formaldehyde (F')) is 10/100/15 to 230/100/100. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a resol type phenolic resin having good water reducibility and reduced environmental burden with little residual monomer.

  Phenolic resins are excellent in heat resistance, adhesiveness, mechanical properties, electrical properties, price advantages, etc., so friction material binders, foam moldings, abrasive binders, wood adhesives, laminates It is widely used as a binder for molds, a binder for molds, a binder for casting cores, a coating agent, an epoxy resin curing agent and the like. Such a phenol resin is obtained by reacting phenols and aldehydes, and an alkali resole resin using an alkali metal or alkaline earth metal hydroxide as a catalyst, or an ammonia resole resin using ammonia, 2 High-ortho type resins using valent metal salts, novolak resins using acids as catalysts, and the like are generally known.

  In recent years, there has been a demand for materials that do not use an organic solvent usage amount or a low organic solvent usage amount from the viewpoint of reducing environmental impact and safety. From this point, a resol resin having a high water dilution property is required. . However, the water-reducibility of such a resole resin usually improves as the molecular weight of the resole resin decreases, so that when the water-reducibility is increased by lowering the molecular weight, the strength and heat resistance of the cured product are reduced. In addition, the reaction does not proceed sufficiently in the polycondensation reaction between phenol and formalin, or there is an increase in residual phenol and volatile residual formalin due to the need to use formalin in excess of phenol. After all, it increased the environmental load. In particular, although resole resins can be made water-based, they cannot be distilled at high temperatures because they are self-curing thermosetting resins, such as unreacted phenols, aldehydes, or mononuclear components. Residual monomers were likely to remain in the resin.

  Conventionally, as a means for reducing the residual monomer of the resole resin from the viewpoint of reducing environmental impact, for example, after reacting formalin and phenol to obtain a resole resin, unreacted formaldehyde remaining in the system by adding ethylene urea There is known a technique for reducing the amount of unreacted formaldehyde by reacting with (see Patent Document 1 below). However, although such a technique is an effective means for reducing the amount of residual monomer, it does not have an effect of improving water dilutability. In order to increase the water-dilutability of the resole resin, the reaction time should be shortened to reduce the molecular weight. In this case, a large amount of unreacted formaldehyde remains, so a large amount of expensive ethylene urea must be added. In addition to being inferior in economic efficiency, there are problems such as a decrease in mechanical strength.

  As described above, in the field of resol resins, there is currently no technology for improving water dilutability while reducing the amount of residual monomer.

JP 2009-13298 A

  The problem to be solved by the present invention is to provide a method for producing a resol type phenolic resin having excellent water reducibility and a reduced amount of residual monomers.

  As a result of intensive studies, the inventors mixed phenols, formaldehyde, and acetone at a predetermined ratio, and reacted in the presence of an alkali catalyst, thereby having high viscosity and excellent water reducibility. And it discovered that the resol type phenol resin with few volatile components was obtained, and came to complete this invention.

  That is, in the present invention, the molar ratio of formaldehyde (F) to alkanone (A) of formaldehyde (F) and alkanone (A) [formaldehyde (F) / alkanone (A)] is 3/1 to 8/1. The reaction product (α) is reacted at a ratio, and then the reaction product (α), phenols (P) and formaldehyde (F ′) are added in the presence of an alkali catalyst in the mass ratio [the The reaction product (α) / phenols (P) / formaldehyde (F ′)] is reacted at a ratio of 10/100/15 to 230/100/100.

  According to the present invention, there is provided a method for producing a resol type phenolic resin having excellent water reducibility while having a high viscosity and having a reduced amount of residual monomers.

  Specifically, in the production method of the present invention, first, formaldehyde (F) and alkanone (A) are mixed at a molar ratio [formaldehyde (F) / alkanone (A)] of 3/1 to 8/1. The reaction product (α) is obtained by reacting at a ratio of Here, when the molar ratio of formaldehyde (F) to alkanone (A) [formaldehyde (F) / alkanone (A)] exceeds 8, the amount of residual formaldehyde in the resol type phenol resin finally obtained Will increase. On the other hand, if it is less than 3, the water-reducibility of the finally obtained resol type phenolic resin will be low. The reaction can be carried out in the presence of an alkali catalyst, and the reaction temperature can be carried out in the range of 25 ° C to 80 ° C. After completion of the reaction, the reaction product (α) can be obtained by cooling to room temperature.

  Next, the obtained reaction product (α), phenols (P) and formaldehyde (F ′) are mixed in the presence of an alkali catalyst in the mass ratio [the reaction product (α) / phenols (P). / Formaldehyde (F ′)] can be reacted at a ratio of 10/100/15 to 230/100/100 to obtain a target phenol resin.

  Here, the mass ratio which is the reaction ratio of the reaction product (α), phenols (P) and formaldehyde (F ′) [the reaction products (α) / phenols (P) / formaldehyde (F ′) ], When the mass of the reaction product (α) is less than 10 parts by mass with respect to 100 parts by mass of the phenols (P), the water-reducibility of the finally obtained resol-type phenol resin becomes low. Moreover, when it exceeds 230 mass parts, the molecular weight of this phenol resin will become low, and hardened | cured material intensity | strength and heat resistance will fall. From the point of being excellent in the balance between these water dilutability and the physical properties of the cured product, it is particularly preferably in the range of 15 to 110 parts by mass.

  On the other hand, when the amount of formaldehyde (F ′) is less than 15 parts by mass with respect to 100 parts by mass of the phenols (P), the water-reducibility of the finally obtained resol-type phenol resin becomes low, and the molecular weight However, the cured product does not have a sufficient strength and heat resistance. Further, when the amount of formaldehyde (F ′) exceeds 100 parts by mass with respect to 100 parts by mass of the phenols (P), the amount of residual formaldehyde in the finally obtained resol type phenol resin increases.

  The reaction between the reaction product (α), phenols (P) and formaldehyde (F ′) is carried out under a temperature condition of 40 to 90 ° C. in the presence of an alkali catalyst. it can.

  The phenols (P) used here include phenol; bisphenols such as bisphenol A and bisphenol F; alkylphenols such as cresol, xylenol, ethylphenol, butylphenol, and octylphenol; polyhydric phenols such as resorcin and catechol; Examples thereof include resole resins having 3 to 10 bodies, novolak resins having an average nucleus number of 3 to 10, halogenated phenols, phenylphenols, aminophenols, and the like. In addition, these phenols are not limited to one type in use, and two or more types may be used in combination. Among these, phenol, alkylphenol, bisphenol, a resole resin having an average number of nuclei of 3 to 10 and a novolak resin having an average number of nuclei of 3 to 10 are preferable from the viewpoint of practicality. Phenol and cresol are preferable from the viewpoint of water dilution and reactivity of the phenol resin.

  Examples of the formaldehyde source of formaldehyde (F) include formalin, paraformaldehyde, and trioxane. Here, it is preferable that formalin is 35-60 mass% formalin from the point of water reducibility and workability | operativity at the time of manufacture.

  Specific examples of the alkanone (A) used in the present invention include acetone and methyl ethyl ketone, and acetone is preferable from the viewpoint of good reactivity and higher molecular weight.

  Examples of the alkali catalyst used in the reaction between the formaldehyde (F) and the alkanone (A) and the reaction between the reaction product (α), the phenol (P) and the formaldehyde (F ′) include, for example, hydroxylation. Alkali metal hydroxides such as sodium, lithium hydroxide and potassium hydroxide, alkaline earth metal oxides and hydroxides such as calcium, magnesium and barium, primary amines such as ammonia and monoethanolamine, diethanolamine Secondary amines such as trimethylamine, triethylamine, triethanolamine, tertiary amines such as diazabicycloundecene, or sodium phosphate, potassium phosphate, sodium carbonate, potassium carbonate, tetra Methyl ammonium hydroxide, hexamethylene tetra Alkaline substance such as emissions and the like.

  Among these, alkali metal hydroxides are preferable from the viewpoint that high water reducibility can be obtained. Moreover, the usage-amount of the said alkali catalyst in reaction with an above described reaction product ((alpha)), phenols (P), and formaldehyde (F ') is the range from which the pH of a reaction system will be 7.5-11. It is preferable from the viewpoint of reactivity.

  The reaction of the reaction product (α), phenols (P) and formaldehyde (F ′) described above has a formaldehyde content of less than 1% by mass, particularly less than 0.5% by mass, and residual phenols (P). It is preferable to carry out until the amount is less than 2% by mass, particularly less than 1% by mass. In the present invention, it is worthy of special mention that even if the reaction is carried out until the amount of unreacted components is remarkably reduced, the water dilutability is not impaired and rather excellent water dilutability is exhibited. The reaction time in the production method of the present invention is about 4 to 9 hours, and the productivity is very good. As described above, a resol type phenol resin having a high molecular weight, a low monomer, and a high water reducibility can be obtained with a reaction time comparable to that of the prior art.

  After completion of the reaction, neutralization may be performed by adding an acidic substance if necessary. Examples of the acidic substance used here include boric acid, lactic acid, sulfuric acid, hydrochloric acid, and the like. When an alkali metal hydroxide is used as the alkali catalyst, it can be obtained by using boric acid as the acidic substance. It is preferable from the point that the water reducibility of a resol type phenol resin can be improved.

  Moreover, although the residual monomer is sufficiently reduced in the resol type phenol resin obtained in the present invention, a formalin scavenger may be used in combination as necessary. Examples of the formalin scavenger include resorcin, urea, melamine, burette and the like.

  The resol-type phenol resin thus obtained can drastically increase water reducibility while extremely reducing the residual monomer component in the resin. Specifically, the water reducibility of the phenol resin is 200% by mass or more. In particular, when an alkali metal hydroxide is used as the alkali catalyst and boric acid is used as the neutralizing agent, the water dilutability is 1000% by mass or more. Here, the water dilutability means the amount of water that can be dissolved in the phenol resin, and the amount of water in the system at the time when the system becomes cloudy when water is gradually added to the phenol resin. Is expressed on the basis of the amount of resin in the system. Specifically, it can be represented by the following formula. Therefore, since the phenol resin has excellent water reducibility, it can be a completely water-based composition using no organic solvent.

Water reducibility (mass%) = [(water mass / resin mass) × 100]

  The resol-type phenolic resin obtained by the production method of the present invention has a sufficiently low amount of residual formaldehyde and residual phenols (P) without performing a step of removing unreacted components. The unreacted raw material components may be removed by a conventional method such as solvent extraction.

  The resol-type phenolic resin thus obtained can be usually used in the form of an aqueous solution, and the concentration of nonvolatile content is preferably in the range of 50 to 60% by mass for ease of handling. Moreover, it is preferable that the pH is the range of 5-8. Furthermore, since the phenol resin is excellent in solubility in water, the viscosity when it is made into an aqueous solution for a high non-volatile content is low. Specifically, the viscosity in an aqueous solution having a nonvolatile content concentration of 50 to 60% by mass is in the range of 50 to 1000 mPa · s.

  The phenol resin has excellent curability, and the gel time on a hot plate at 150 ° C. is 20 to 50% as compared with a normal resol type phenol resin. In addition to excellent storage stability at 15 ° C., the cured product has excellent mechanical strength.

  Since the resol type phenolic resin obtained by the production method of the present invention described in detail above has both excellent water dilutability and low volatile components, it can be used for adhesives, paints, mold binders, casting cores. It is used for binders for friction, binders for friction materials, binders for refractories, foamed molded products and the like.

  Among these, for adhesives and coatings, specifically, it can be used as a vehicle resin for water-based paints, a binder resin for water-based inks, water-based adhesives for plywood, and water-based adhesives for various plastics. It is also useful as a binder for fibrous substances such as pulp and glass fiber and particulate substances such as wood powder, cellulose powder and ceramic.

  When these adhesives and paints are used, a crosslinking material such as an aqueous epoxy resin, an aqueous melamine resin, an aqueous blocked isocyanate, or an aqueous reactive urethane resin may be used in combination.

  In addition, as described above, the resol type phenolic resin obtained in the present invention can be used as a paint / adhesive in a completely aqueous system that does not contain any solvent. In order to improve it, you may mix | blend drying acceleration | stimulation components, such as alcohol, in the ratio of 0.01-15 mass% in a composition. In addition, pigments such as rust preventive pigments, colored pigments, extender pigments, thixotropic agents, viscosity modifiers, flow aids, surface modifiers, primary rust preventive agents, antifoaming agents, antiseptics, etc. Various additives such as fungicides may be added.

  Further, when used as a binder for a mold or a binder for a casting core, for example, the resol type phenol resin can be mixed with a molding sand together with a curing agent if necessary, and cured and shaped into a predetermined shape. .

  In addition, when used as a binder for friction materials, natural diamond abrasive grains, artificial diamond abrasive grains, alumina abrasive grains, silicon carbide abrasive grains, etc. are blended and dispersed together with the resol type phenolic resin, and cured. By doing so, an abrasive can be obtained.

When used as a refractory binder, the phenol resin can be kneaded with a refractory aggregate to obtain a molded product such as a refractory brick. Examples of the refractory aggregate for, _{e.g., SiO 2, MgO, Al 2} O 3, include those containing graphite.

  The foamed molded product can be obtained by melt-kneading a foaming agent in the phenol resin and then foam-molding. Examples of the blowing agent used here include hydrocarbons such as butane, pentane, cyclopentane, isopentane, and hexane, halogenated hydrocarbons such as methylene chloride and propane chloride, perfluoroalkanes such as perfluorohexane and perfluoropentane, and perfluoropentane. Hydrofluoroethers such as fluorobutyl methyl ether and perfluorobutyl ethyl ether, hydrofluorocarbons such as difluoromethane, tetrafluoroethane, and pentafluoroethane, dichloroethane, trichloroethane, tetrachloromethane, dichloromonofluoroethane, dichlorotrifluoroethane, dichloro Fluoroamines such as hydrochlorofluorocarbons such as pentafluoropropane, perfluoromorpholine and perfluoromethylmorpholine And the like. The amount of the blowing agent used is preferably in the range of 0.3 to 10 parts by mass per 100 parts by mass of the resol type phenol resin.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Measurement of residual phenol amount: The residual phenol amount was measured by GPC.
The amount of residual formaldehyde is measured by HPLC. Water dilution measurement: Water is gradually added to the obtained phenolic resin, and the amount of water in the system when the system becomes cloudy is used as a reference for the amount of resin in the system. Measured.

[HPLC measurement method]
Equipment: “Waters HPLC system” manufactured by Waters Corporation
Column: “Waters Symmetry C18; 5 μm, 4.6 × 250 mm”
Column temperature: 30 ° C
Eluent: methanol / water = 43/57
Flow rate: 0.8 sec / min Detection wavelength: 200-400 nm
Injection volume: 5 μm

[GPC measurement conditions]
Column: Showa Denko "Shodex KF803"
Showa Denko "Shodex KF802"
Showa Denko "Shodex KF802"
Showa Denko "Shodex KF801"
Detector: RI (Differential refraction diameter)
Measurement conditions: Column temperature 40 ° C
Developing solvent Tetrahydrofuran
Flow rate: 1.0 ml / min Standard: Monodispersed polystyrene with a known molecular weight Sample: 1.0 mass% tetrahydrofuran solution (25 μl) in terms of resin solid content.

Example 1
42 mass% formalin 516 g and acetone 70 g were put into a 1000 ml reaction vessel, 30 mass% sodium hydroxide 8 g was added and reacted at 30 to 40 ° C. for 30 minutes. Subsequently, it heated at 50 degreeC and hold | maintained for 30 minutes, after adding 2 mass of 30 mass% sodium hydroxide, and also hold | maintaining for 1.5 hours, it cooled to room temperature and obtained the acetone- formalin adduct.
300 g of the obtained acetone-formalin adduct, 300 g of phenol and 256 g of 42% by mass formalin are mixed, then 30% by mass sodium hydroxide is added to adjust the pH to 9.5-10, and the mixture is heated to 75 ° C. The reaction was carried out until the mass became 200% by mass and the viscosity became 100 to 200 mPa · s. It was then cooled and 10 g resorcin was added. At room temperature, 2-4 g of powdered boric acid was added and sufficiently stirred.
The obtained resol type phenol resin had a nonvolatile content concentration of 54 to 56 mass%, a water dispersibility of 300 mass%, a pH of 6-8, and a viscosity of 200 to 300 mPa · s. Unreacted phenol was about 1% by mass, and unreacted formalin was about 0.5% by mass.

Comparative Example 1
342 g of phenol and 390 g of 42% by mass formalin were placed in a 1000 ml reaction vessel and stirred. Then, 10 g of a 48% by mass aqueous sodium hydroxide solution was added, the temperature was raised to 80 ° C., and the temperature was maintained for 6 hours. It was then cooled to room temperature.
The resol type phenol resin thus obtained had a nonvolatile content concentration of 56% by mass, a molecular weight of about 700, a water dilutability of 10-20% by mass, a pH of about 8.5, and a viscosity of 150 mPa · s.
The unreacted phenol was 0.3% by mass, the unreacted formaldehyde was 5% by mass, and the gel time on a 150 ° C. hot plate was 100 s.

Comparative Example 2
376 g of phenol and 206 g of 42% by mass of formalin (0.72 mol with respect to 1 mol of phenol) are placed in a 1000 ml reaction vessel, stirred, added with 1.1 g of oxalic acid, heated to 100 ° C. and held for 1 hour. did. Next, 1.1 g of oxalic acid was added and the reaction was continued for another hour.
Next, 228.5 g of 42% by mass formalin was added to the reaction vessel, 48% by mass sodium hydroxide was added to adjust the pH to 8.5-9, and the mixture was heated to 75-80 ° C. Held for hours.
It was then cooled to room temperature.
The resol-type phenol resin thus obtained had a nonvolatile content concentration of 56% by mass, a molecular weight of about 700 or more, a water dilutability of 10-20% by mass, a pH of about 8.5, and a viscosity of about 500 mPa · s.
Unreacted phenol was 1% by mass, and unreacted formaldehyde was 3% by mass.

Comparative Example 3
565 g of phenol and 280 g of formalin of 42% by mass (0.65 mol with respect to 1 mol of phenol) are placed in a 1000 ml reaction vessel, stirred, 2.0 g of oxalic acid is added, and the temperature is raised to 100 ° C. and held for 1 hour did. Next, 2.0 g of oxalic acid was added, the reaction was continued for another hour, further heated to 180 ° C. and held for 3 hours. Unreacted phenol was removed under reduced pressure and cooled to room temperature to obtain a novolak resin.
To 312 g of the novolac resin thus obtained, 220 g of methanol and 145% of formalin 145% were added, and sodium hydroxide was added to adjust the pH to about 9, and then the temperature was raised to 75 ° C. The reaction was continued until 300 to 600 mPa · s.
The resol-type phenol resin thus obtained has a non-volatile concentration of 51 to 53% by mass, a molecular weight of about 800 or more, a water dilutability of 50-80% by mass, pH 8-10, 1% by mass of unreacted phenol, The reaction formaldehyde was 2% by mass or more.

Comparative Example 4
400 g of phenol and 676 g of 42% by mass of formalin were put in a 2000 ml reaction vessel, stirred, 21.2 g of 48% aqueous sodium hydroxide solution was added, the temperature was raised to 80 ° C., and the temperature was maintained for 4 hours. The reaction temperature was lowered to 50 ° C., 14 g of ethylene urea was added, and the mixture was stirred for 30 minutes and cooled to room temperature. The resulting resin had a non-volatile concentration of 53 to 57%, a molecular weight of about 500 or more, a water dilution of 180% by mass, pH 8-10, 3% by mass of unreacted phenol, and 0.8% by mass of unreacted formaldehyde. It was.

Claims (4)

Reaction by reacting formaldehyde (F) and alkanone (A) at a ratio of formaldehyde (F) to alkanone (A) [formaldehyde (F) / alkanone (A)] of 3/1 to 8/1. A product (α) is obtained, and then the reaction product (α), phenols (P) and formaldehyde (F ′) are mixed in the presence of an alkali catalyst in the mass ratio [the reaction product (α). / Phenols (P) / formaldehyde (F ′)] is reacted at a ratio of 10/100/15 to 230/100/100. 6. The phenols (P) are selected from the group consisting of phenol, alkylphenol, bisphenol, a resole resin having an average nucleus number of 3 to 10, and a novolak resin having an average nucleus number of 3 to 10. Of producing phenolic resin. The method for producing a phenol resin according to claim 1, wherein boric acid is further added after completion of the reaction. The method for producing a phenol resin according to claim 3, wherein the alkali catalyst is an alkali metal hydroxide.