JP2022089312A - Phenol resin composition - Google Patents

Abstract

To provide a phenol resin composition which extremely reduces contents of both free phenol and free aldehyde, has high water solubility, and is excellent in handleability or workability.SOLUTION: A phenol resin composition contains a water-soluble resol type phenol resin, an amino acid or its salt, in which the amino acid is a water-soluble amino acid having a molecular weight of 89 or more.SELECTED DRAWING: None

Description

The present invention relates to a phenolic resin composition containing a water-soluble resol type phenolic resin. More specifically, it relates to a phenolic resin composition having a reduced content of formaldehyde and phenol.

Phenol resin is a typical thermosetting resin used in many fields due to its heat resistance and high mechanical strength of the cured product. Phenol resins are used, for example, by impregnating or applying them to various base materials, or as binders for various organic and inorganic base materials. Phenol resins are roughly classified into novolak-type phenol resins that are heat-cured by adding a curing agent such as hexamethylenetetramine and resol-type phenol resins that are heat-cured by themselves. It has been.

Among these phenolic resins, hydrophilicity is used in applications where ammonia-free is required for environmental friendliness and work environment improvement, and when solvent-free is required, applications used in the form of aqueous solutions or emulsions. High resole-type phenolic resins are often used. The water-soluble resole resin is used, for example, as a binder for abrasive cloth. Resol resin has excellent abrasive grain holding power and heat resistance, and high grindability can be obtained.

However, this resol-type phenolic resin contains unreacted phenols and unreacted aldehydes, which are undesired substances from the viewpoint of protecting the air environment and the human body environment. In order to obtain a resol-type phenol resin having a reduced formaldehyde content, an excess amount of phenol may be reacted with aldehydes, but a resol-type phenol resin obtained by using an excess amount of phenol. Since it contains a large amount of unreacted phenols, it has poor curability, and the mechanical strength of the obtained cured product may not reach the level required by the market, which may limit its use. In addition, the resol-type phenol resin obtained by using an excess amount of phenol with respect to aldehydes contains a large amount of unreacted phenol, and therefore, it is not preferable to use it from the viewpoint of environment and occupational safety and health.

As a technique for solving the above problems, Patent Document 1 describes a method for producing a resol resin capable of reducing the amount of unreacted monomers such as formaldehyde and phenol. In Patent Document 1, a liquid resin exhibiting a free phenol level of 0.5% or less is produced by blending a phenol-formaldehyde condensate with 0.1 to 0.5 mol of glycine per 1 mol of starting phenol. The method is described.

Japanese Patent No. 6001536

However, the method described in Patent Document 1 has room for further improvement in both improving the water solubility of the obtained phenol resin and reducing free formaldehyde and free phenol.

The present invention has been made in view of the above problems, and the content of both free phenol and free aldehyde, which are unreacted monomers, is reduced, and the present invention has high water solubility, and thus is easy to handle or work. It is an object of the present invention to provide an excellent phenolic resin composition.

According to the present invention
Water-soluble resol type phenol resin and
Contains amino acids or salts thereof,
A phenol resin composition is provided in which the amino acid is a water-soluble amino acid having a molecular weight of 89 or more.

According to the present invention, there is provided a phenol resin composition in which the contents of both free phenol and free aldehyde are significantly reduced, and the phenol resin composition has high water solubility and is therefore excellent in handleability or workability.

Hereinafter, embodiments of the present invention will be described. In the present specification, the notation "a to b" in the description of the numerical range means "a or more and b or less" unless otherwise specified. For example, "5 to 90% by mass" means "5% by mass or more and 90% by mass or less".

(Phenol resin composition)
The phenolic resin composition of the present embodiment contains a water-soluble resole-type phenolic resin and an amino acid or a salt thereof. In this embodiment, the amino acid is a water-soluble amino acid having a molecular weight of 89 or more.

The phenol resin composition of the present embodiment contains a water-soluble resole-type phenol resin and a water-soluble amino acid having a molecular weight of 89 or more or a salt thereof. By containing the amino acid or a salt thereof in the phenol resin composition of the present embodiment, the amount of free aldehyde and free phenol, which are unreacted residual monomers inevitably contained in the water-soluble resole-type phenol resin, is reduced. Therefore, the environmental load and the load on the human body are reduced. The reason why the amount of free aldehyde and free phenol is reduced by the amino acid or its salt is not always clear, but the reaction or interaction between the amino acid and the free aldehyde and free phenol in the phenol resin composition causes the free aldehyde. And free phenol is believed to exist as a non-volatile compound or an inert compound.

Further, the phenol resin composition of the present embodiment is improved in stability over time by containing an amino acid or a salt thereof. Here, the temporal stability of the phenol resin composition means that the change in the characteristics of the resin composition with time is small. Changes in the characteristics of the resin composition over time include increasing the molecular weight of the phenolic resin contained in the resin composition and increasing the viscosity of the resin composition. Since the pH of the phenolic resin composition of the present embodiment is maintained in the neutral region by the buffering action of amino acids, the resole-type phenolic resin contained in the resin composition has a high molecular weight and unreacted free formaldehydes. Further polymerization reaction between the and free phenol is suppressed , so that the viscosity of the phenolic resin is increased and the properties of the resin composition are hardly or completely changed.
Hereinafter, the components to be blended in the phenol resin composition of the present embodiment will be described in detail.

(Water-soluble resole-type phenol resin)
The water-soluble resol-type phenol resin used in the phenol resin composition of the present embodiment is obtained by reacting phenols and aldehydes in a reaction solvent under a basic catalyst under the predetermined conditions described below. It is a resin that can be used.

Examples of the phenols used for the synthesis of the water-soluble resol-type phenol resin used in the present embodiment include phenols; cresols such as o-cresol, m-cresol, p-cresol; o-ethylphenol, m-. Ethylphenols such as ethylphenol and p-ethylphenol; butylphenols such as isopropylphenol, butylphenol and p-tert-butylphenol; p-tert-amylphenol, p-octylphenol, p-nonylphenol, p-cumylphenol and the like. Alkylphenols; Halogened phenols such as fluorophenols, chlorophenols, bromophenols, iodophenols; monohydric phenol substituents such as p-phenylphenols, aminophenols, nitrophenols, dinitrophenols, trinitrophenols: and 1- Monovalent phenols such as naphthol and 2-naphthol; polyhydric phenols such as resorcin, alkylresorcin, pyrogallol, catechol, alkylcatechol, hydroquinone, alkylhydroquinone, fluoroglucolcin, bisphenol A, bisphenol F, bisphenol S, dihydroxynaphthalin, etc. Can be mentioned. These may be used alone or in admixture of two or more.

Examples of the aldehydes used for the synthesis of the water-soluble resol type phenol resin used in the present embodiment include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural and glioxal. , N-butylaldehyde, caproaldehyde, allylaldehyde, benzaldehyde, crotonaldehyde, achlorine, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, salicylaldehyde and the like. These may be used alone or in combination of two or more. It is also possible to use precursors of these aldehydes or solutions of these aldehydes. Above all, it is preferable to use an aqueous formaldehyde solution from the viewpoint of manufacturing cost.

Examples of the basic catalyst used for synthesizing the water-soluble resole-type phenol resin used in the present embodiment include alkaline metal such as sodium hydroxide, potassium hydroxide and calcium hydroxide, or alkaline earth metal water. Oxides; carbonates such as sodium carbonate and calcium carbonate; oxides such as lime; sulfites such as sodium sulfite; phosphates such as sodium phosphate; ammonia, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine , Hexamethylenetetramine, amines such as pyridine and the like.

Water is generally used as the reaction solvent used for synthesizing the water-soluble resol type phenol resin used in the present embodiment, but an organic solvent may be used. Specific examples of such an organic solvent include alcohols, ketones, aromatics and the like. Specific examples of alcohols include methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin and the like. Specific examples of the ketones include acetone, methyl ethyl ketone and the like. Specific examples of aromatics include toluene, xylene and the like.

Examples of the form of the resole-type phenol resin include solids, aqueous solutions, solvent solutions, and aqueous dispersions. When an organic solvent is used as the reaction solvent for the synthesis of the water-soluble resole-type phenol resin, the organic solvent is removed from the reaction solution containing the reaction product by a known means such as extraction and drying.

The resol-type phenol resin used in the present embodiment contains phenols (P) and aldehydes (F) in a compounding molar ratio (F / P) of 0.8 or more, preferably 0.8 or more and 3.0. Hereinafter, the above-mentioned basicity as a polymerization catalyst is further preferably charged in a reaction vessel at a ratio of 1.0 or more and 2.8 or less, and even more preferably 1.2 or more and 2.5 or less. It is obtained by adding a catalyst and performing reflux for an appropriate time (for example, 3 to 6 hours). When the compounding molar ratio (F / P) of the phenols (P) and the aldehydes (F) is less than 0.8, the weight average molecular weight of the water-soluble resol-type phenol resin produced is small and the heat resistance is high. May be inferior to. When the compounding molar ratio (F / P) of the phenols (P) and the aldehydes (F) exceeds 3.0, the gelation of the resin is likely to proceed during the reaction, and the reaction efficiency is lowered. However, it is not preferable because a water-insoluble high-molecular-weight resole-type phenol resin is produced. The reaction temperature is, for example, 40 ° C to 120 ° C, preferably 60 ° C to 100 ° C. As a result, gelation can be suppressed and a water-soluble resol-type phenol resin having a target molecular weight can be obtained. The weight average molecular weight of the water-soluble resole-type phenol resin is preferably 250 to 3000, and more preferably 300 to 2000. The resol-type phenol resin having a molecular weight in the above range has water solubility and high heat resistance.

(amino acid)
The amino acid blended in the phenol resin composition of the present embodiment is not particularly limited as long as it has a molecular weight of 89 or more and is water-soluble. Examples include neutral amino acids such as alanine, valine and serine; acidic amino acids such as glutamine; and basic amino acids such as asparagine. The amino acid may be in the form of a salt, and examples of the amino acid salt include sodium salts and potassium salts of amino acids. Amino acids or salts thereof may be used alone or in combination of two or more.

Among them, amino acids and salts thereof preferably used include aspartic acid and sodium aspartate. By using such an amino acid, the pH of the obtained phenol resin composition can be kept neutral, and the water solubility can be kept high.

(Manufacturing method of phenol resin composition)
The phenolic resin composition of the present embodiment is prepared by dissolving a water-soluble resol-type phenol resin and an amino acid component in water by a known means to form an aqueous solution, or during the synthesis step of the above-mentioned water-soluble resol-type phenol resin. It can be obtained by adding an amino acid.

The blending amount of the amino acid or a salt thereof is, for example, 0.1 to 30% by mass, preferably 0.5 to 25% by mass, and more preferably 1 to 1 to 30% by mass with respect to the water-soluble resole-type phenol resin. It is 20% by mass. By blending an amino acid or a salt thereof within the above range, free aldehydes and free phenols remaining in the water-soluble resole-type phenol resin can be reduced.

The resin composition of the present embodiment is provided as an aqueous solution having a solid content of 10% by mass or more and 80% by mass or less. The solid content of the resin composition of the present embodiment can be adjusted according to the use of the resin composition by adjusting the amount of water as a solvent. For example, when the resin composition of the present embodiment is used as an adhesive for a friction material, the solid content is preferably 50 to 80% by mass. As a result, the viscosity of the obtained resin composition becomes appropriate for application to the friction base material, and sufficient bonding strength can be obtained for use as a friction material. When the resin composition of the present embodiment is used for impregnating a base material, the solid content is preferably 10 to 70% by mass. As a result, a resin composition having excellent handleability and excellent impregnation property can be obtained, and thus a high-strength / high-quality molded product can be produced with excellent production efficiency.

In the phenol resin composition of the present embodiment, the content of unreacted free phenols is 1% by mass or less, preferably 0.8% by mass or less, more preferably 0, based on the entire phenol resin composition. It has been reduced to less than 6.6% by mass.

Further, in the phenol resin composition of the present embodiment, the content of unreacted free aldehydes is 1% by mass or less, preferably 0.8% by mass or less, more preferably, with respect to the entire phenol resin composition. It is reduced to 0.6% by mass or less.

The pH of the phenolic resin composition of the present embodiment is close to neutral, for example, 6 to 8, preferably 6.5 to 7.8, and more preferably 6.8 to 7.5. be. Such pH is achieved by the presence of amino acids in the phenolic resin composition. The phenolic resin composition of the present embodiment is excellent in stability over time by having a pH in the above range.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Example 1)
To a reactor equipped with a stirrer, a reflux condenser and a thermometer, 1000 parts by weight of phenol, 1638 parts by weight of a 37% formalin aqueous solution (F / P molar ratio = 1.9), and 30 parts by weight of sodium hydroxide were added. The reaction was carried out at 90 ° C. for 70 minutes. After adding 500 parts by weight of water to this, 75 parts by weight of alanine was added and dissolved at 60 ° C. to obtain a resin composition. The obtained resin composition was transparent, had a solid content of 48%, had a pH of 7.4, and was 2.6 times water-dilutable at 25 ° C.
The amount of alanine in the resin composition calculated from the amount of each component used was 5% by mass with respect to the total solid content of the resin composition. Further, in this resin composition, the amount of free phenol measured by gas chromatography was 0.9% by mass, and the amount of free formaldehyde measured by the titration method was 0.3% by mass.

(Example 2)
A resin composition was obtained by synthesizing in the same manner as in Example 1 except that the alanine of Example 1 was changed to aspartic acid. The obtained resin composition was transparent, had a solid content of 48%, had a pH of 7.0, and was 2.3 times water-dilutable at 25 ° C.
The amount of aspartic acid in the resin composition calculated from the amount of each component used was 5% by mass with respect to the total solid content of the resin composition. Further, in this resin composition, the amount of free phenol measured by gas chromatography was 0.9% by mass, and the amount of free formaldehyde measured by the titration method was 0.2% by mass.

(Example 3)
A resin composition was obtained by synthesizing in the same manner as in Example 1 except that the alanine of Example 1 was changed to sodium aspartate. The obtained resin composition was transparent, had a solid content of 48%, had a pH of 7.5, and was 20-fold or more water-dilutable at 25 ° C.
The amount of sodium aspartate in the resin composition calculated from the amount of each component used was 5% by mass with respect to the total solid content of the resin composition. Further, in this resin composition, the amount of free phenol measured by gas chromatography was 0.8% by mass, and the amount of free formaldehyde measured by the titration method was 0.3% by mass.

(Example 4)
A resin composition was obtained by the same synthesis as in Example 3 except that the sodium aspartate of Example 3 was changed to 15 parts by weight. The obtained resin composition was transparent, had a solid content of 47%, had a pH of 7.6, and was 10-fold water-dilutable at 25 ° C.

The amount of sodium aspartate in the resin composition calculated from the amount of each component used was 1% by mass with respect to the total solid content of the resin composition. Further, in this resin composition, the amount of free phenol measured by gas chromatography was 1.0% by mass, and the amount of free formaldehyde measured by the titration method was 0.4% by mass.
(Example 5)
A resin composition was obtained by the same synthesis as in Example 3 except that the sodium aspartate of Example 3 was changed to 220 parts by weight. The obtained resin composition was transparent, had a solid content of 50%, had a pH of 7.0, and had a water dilutability of 20 times or more at 25 ° C.
The amount of sodium aspartate in the resin composition calculated from the amount of each component used was 15% by mass with respect to the total solid content of the resin composition. Further, in this resin composition, the amount of free phenol measured by gas chromatography was 0.7% by mass, and the amount of free formaldehyde measured by the titration method was 0.2% by mass.

(Comparative Example 1)
The same synthesis as in Example 1 was performed without adding alanine in Example 1 to obtain a resin composition. The obtained resin composition was transparent, had a solid content of 49%, had a pH of 8.9, and was 1.8 times water-dilutable at 25 ° C.
In this resin composition, the amount of free phenol measured by gas chromatography was 1.6% by mass, and the amount of free formaldehyde measured by the titration method was 1.0% by mass.

The results are summarized in Table 1 below.

In the phenol resin composition of the example containing amino acids, the amounts of free phenol and free formaldehyde contained as unreacted monomers in the resin composition were reduced.

Claims (3)

Water-soluble resol type phenol resin and
Contains amino acids or salts thereof,
The amino acid is a water-soluble amino acid having a molecular weight of 89 or more.
Phenolic resin composition. The phenolic resin composition according to claim 1, wherein the amino acid or a salt thereof is at least one selected from alanine, valine, serine, aspartic acid, and glutamic acid, and salts thereof. The phenol resin composition according to claim 1 or 2, wherein the amino acid or a salt thereof is in an amount of 0.1% by mass or more and 30% by mass or less with respect to the total solid content of the phenol resin composition.