TW201623356A - Epoxy resin and hardener for epoxy resin - Google Patents

Abstract

An epoxy resin and a hardener for epoxy resins, the epoxy resin being characterizing by being obtained by at least reacting epichlorohydrin with lignin modified with a carboxylic acid.

Description

Epoxy resin and epoxy resin hardener

The present invention relates to an epoxy resin and an epoxy resin hardener.

The epoxy resin cured product is usually produced by blending and hardening an epoxy resin and an epoxy resin hardener, and is widely used in various industrial fields such as electronic components such as semiconductor sealing materials or coating materials and adhesives. .

In recent years, as an epoxy resin composition containing such an epoxy resin and an epoxy resin curing agent, it has been studied to use a plant-derived raw material suitable for carbon neutralization from the viewpoint of suppressing environmental damage. Specifically, an epoxy resin composition containing an epoxy resin and lignophenol as a main component has been proposed, and an epoxidized lignan is also proposed as an epoxy resin (see Patent Document 1).

Further, as the epoxy resin, in addition to the above, an epoxy resin obtained by reacting epichlorohydrin with a gramineous plant lignin recovered from a pulp waste liquid obtained by an alkali distillation method is also proposed, and It is also proposed to use the above-mentioned gramineous plant lignin as an epoxy resin hardener (refer to Patent Document 2).

Further, as the epoxy resin, there is proposed a wood obtained by reacting epichlorohydrin with a phenolic lignin recovered from a pulp waste liquid obtained by an alkali distillation method and a phenol under an acid catalyst. The epoxy resin obtained by the reaction of the phenol resin is also used, and the above-mentioned lignin phenol resin is also proposed as an epoxy resin hardener (see Patent Document 3).

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2009-292884

Patent Document 2: Japanese Patent Laid-Open Publication No. 2011-144340

Patent Document 3: Japanese Patent Laid-Open No. 2011-99083

However, in the epoxy resin composition described in Patent Document 1, since the molecular weight of the lignan as a raw material component is relatively large, there is a problem that the fluidity is relatively low and the workability is poor.

In the case of using the epoxy resin and the epoxy resin curing agent described in Patent Document 2 and Patent Document 3, the heat resistance of the obtained cured epoxy resin may be insufficient.

Therefore, an object of the present invention is to provide an epoxy resin and an epoxy resin hardener which are capable of obtaining an epoxy resin cured product excellent in workability and heat resistance.

The epoxy resin of the present invention is characterized in that it is obtained by reacting at least a carboxylic acid-modified lignin with epichlorohydrin.

Further, in the epoxy resin of the present invention, it is preferred that the lignin modified with the above carboxylic acid is phenol-modified.

Further, in the epoxy resin of the present invention, it is preferred that the lignin in which the carboxy group is modified with a carboxylic acid is extracted by an organic solvent.

Further, the epoxy resin hardener of the present invention is characterized in that it contains A carboxylic acid modified lignin.

Further, in the epoxy resin hardener of the present invention, it is preferred that the lignin modified with the above carboxylic acid is phenol-modified.

Further, in the epoxy resin hardener of the present invention, it is preferred that the lignin modified with the above carboxylic acid is extracted by an organic solvent.

Since the epoxy resin and the epoxy resin hardener of the present invention are obtained by using carboxylic acid-modified lignin, the handleability is excellent, and the heat resistance of the cured epoxy resin can be improved.

Epoxy resin

The epoxy resin of the present invention can be obtained by reacting a carboxylic acid-modified lignin (hereinafter sometimes referred to as a carboxylic acid-modified lignin) with epichlorohydrin.

In the carboxylic acid-modified lignin, for example, a carboxylic acid having one carboxyl group (hereinafter sometimes referred to as a monofunctional carboxylic acid) may be mentioned as the carboxylic acid, and specific examples thereof include a saturated aliphatic monofunctional carboxylic acid. An unsaturated aliphatic monofunctional carboxylic acid, an aromatic monofunctional carboxylic acid or the like.

Examples of the saturated aliphatic monofunctional carboxylic acid include acetic acid, propionic acid, butyric acid, lauric acid, and the like.

Examples of the unsaturated aliphatic monofunctional carboxylic acid include acrylic acid, methacrylic acid, and linoleic acid.

Examples of the aromatic monofunctional carboxylic acid include benzoic acid, 2-phenoxybenzoic acid, and 4-methylbenzoic acid.

These carboxylic acids may be used singly or in combination of two or more.

The carboxylic acid is preferably a saturated aliphatic monofunctional carboxylic acid, more preferably acetic acid. When the above carboxylic acid is used, the carboxylic acid-modified lignin can be easily obtained, and the obtained carboxylic acid-modified lignin is as follows, since the solubility in the organic solvent is relatively high, and the melting temperature is Relatively low temperature (about 100 to 200 ° C), so the operability is also excellent.

The lignin is composed of guaiacyl lignin (G type), syringyl lignin (S type), p-hydroxyphenyl lignin (H type) and other basic skeletons. A molecular phenolic compound is included in the whole plant. As a natural extract of such natural lignin, for example, it is known that it is contained in a waste liquid (black liquor) discharged from a plant material by a soda method, a sulfurous acid method, a purification method, or the like. Quality, sulfite lignin, refined lignin, etc.

Specific examples of the lignin include lignin derived from woody plants and lignin derived from herbaceous plants.

Examples of the lignin derived from the woody plant include coniferous lignin contained in a conifer (for example, cedar), for example, a broad-leaved tree lignin contained in a broad-leaved tree. The lignin derived from the woody plant does not contain the lignin with the H-type as the basic skeleton. For example, the coniferous lignin is based on the G-type, and the broad-leaved lignin is based on the G-type and the S-type. skeleton.

Examples of the lignin derived from the herbaceous plant include grass lignin or the like contained in gramineous plants (wheat straw, rice straw, corn, bamboo, etc.). The lignin derived from the herbaceous plant is based on all of the H-form, the G-form, and the S-form.

These lignin may be used singly or in combination of two or more.

As the lignin, preferred is lignin derived from a herbaceous plant, and more preferably a lignin derived from a herbaceous plant obtained from a corn stover (corn core, stem, leaf, etc.). .

In addition, as the lignin, a basic skeleton containing an H-form is preferably contained in a ratio of 9% by mass or more, and more preferably 14% by mass or more, from the viewpoint of reactivity.

The method for producing the carboxylic acid-modified lignin is not particularly limited and can be carried out according to a known method.

Specifically, for example, a carboxylic acid can be obtained in the form of a pulp waste liquid by using a carboxylic acid (preferably acetic acid) for the plant material (for example, conifer, broadleaf, grass, etc.) which is a raw material of lignin. Modified lignin.

The method of the distillation is not particularly limited. For example, a plant material which is a raw material of lignin is mixed with a carboxylic acid and an inorganic acid (for example, hydrochloric acid, sulfuric acid, etc.) to carry out a reaction.

The carboxylic acid (100% conversion) is, for example, 500 parts by mass or more, preferably 900 parts by mass or more, for example, 30,000 parts by mass or less, based on 100 parts by mass of the plant material which is a raw material of lignin. It is preferably 15,000 parts by mass or less.

In addition, the inorganic acid (100% conversion) is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, for example, 10 parts by mass, based on 100 parts by mass of the plant material which is a raw material of lignin. Hereinafter, it is preferably 5 parts by mass or less.

Further, as a reaction condition, the reaction temperature is, for example, 30 ° C or more. It is preferably 50 ° C or more, for example, 400 ° C or less, preferably 250 ° C or less. Further, the reaction time is, for example, 0.5 hours or longer, preferably 1 hour or longer, for example, 20 hours or shorter, preferably 10 hours or shorter.

By this evaporation, pulp is obtained, and carboxylic acid-modified lignin is obtained in the form of a pulp waste liquid.

Then, in this method, the pulp is separated by a known separation method such as filtration, and the filtrate (pulp waste liquid) is recovered, and if necessary, an unreacted carboxylic acid is used, for example, by a known method using a rotary evaporator, vacuum distillation, or the like. Removal (distillation removal). Thereafter, a large excess of water is added to precipitate and filter the carboxylic acid-modified lignin, thereby recovering the carboxylic acid-modified lignin as a solid.

Further, the method for obtaining the carboxylic acid-modified lignin is not limited to the above, and for example, a carboxy group can be obtained by reacting lignin (hereinafter, unmodified lignin) which has not been modified with a carboxylic acid with a carboxylic acid. Acid modified lignin.

In such a method, as the unmodified lignin, a powdery unmodified lignin is preferable.

The average particle diameter of the powdery unmodified lignin is, for example, 0.1 μm or more, preferably 5 μm or more, for example, 1000 μm or less, or preferably 500 μm or less.

When the average particle diameter is in the above range, aggregation of unmodified lignin can be suppressed, and unmodified lignin can be favorably dispersed with respect to the carboxylic acid.

Further, the powdery unmodified lignin can be obtained by drying and pulverizing the block-shaped unmodified lignin by a known method, and a commercially available product can also be used.

As a method of reacting unmodified lignin with a carboxylic acid, for example, unmodified lignin is mixed with a carboxylic acid and a mineral acid (for example, hydrochloric acid, sulfuric acid, etc.) so that Its reaction.

The carboxylic acid (100% conversion) is, for example, 300 parts by mass or more, preferably 500 parts by mass or more, for example, 15,000 parts by mass or less, preferably 100 parts by mass or less, based on 100 parts by mass of the unmodified lignin. 10,000 parts by mass or less.

In addition, the inorganic acid (100% conversion) is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, for example, 10 parts by mass or less, based on 100 parts by mass of the unmodified lignin. It is preferably 5 parts by mass or less.

Further, as the reaction conditions, the reaction temperature is, for example, 30 ° C or higher, preferably 50 ° C or higher, for example, 400 ° C or lower, preferably 250 ° C or lower. Further, the reaction time is, for example, 0.5 hours or longer, preferably 1 hour or longer, for example, 20 hours or shorter, preferably 10 hours or shorter.

Such a carboxylic acid-modified lignin is excellent in handleability.

That is, lignin which has not been modified with a carboxylic acid has a relatively low solubility in an organic solvent and does not melt, and therefore has poor handleability depending on the use.

On the other hand, as described above, the carboxylic acid-modified lignin is due to a polar organic solvent (for example, acetone, methanol, phenol, tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N,N-dimethylmethyl). The solubility of decylamine, N,N-dimethylacetamide, dimethyl hydrazine, hexamethylphosphonium decylamine, etc. is relatively high, and the melting temperature is relatively low temperature (about 100 to 200 ° C) Therefore, the operability is excellent.

Further, the carboxylic acid-modified lignin is preferably extracted from the product (crude product) obtained by the above method by an organic solvent.

The organic solvent may, for example, be the above-mentioned polar organic solvent, and acetone is preferred.

The carboxylic acid can be obtained by extracting the carboxylic acid modified lignin with an organic solvent. By modifying the modified lignin, it is possible to improve the heat resistance of the cured epoxy resin (described later).

Further, the extraction method is not particularly limited, and a known method can be employed.

The extraction ratio of the carboxylic acid-modified lignin is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and for example, 90% by mass or less, preferably 80% by mass or less.

Further, the carboxylic acid-modified lignin is preferably phenol-modified.

To phenol-modified carboxylic acid-modified lignin, for example, a carboxylic acid-modified lignin (a phenol-modified carboxylic acid-modified lignin) is reacted with a phenol under an acid catalyst.

Examples of the phenols include phenol, cresol (o-cresol, m-cresol, p-cresol, etc.), resorcin, and the like.

These phenols may be used alone or in combination of two or more.

The phenol is preferably cresol from the viewpoint of performance improvement, and more preferably p-cresol.

The blending ratio of the phenols is, for example, 100 parts by mass or more, preferably 300 parts by mass or more, for example, 5,000 parts by mass or less, preferably 100 parts by mass or less, based on 100 parts by mass of the phenol-modified lignin modified phenol. 3000 parts by mass or less.

The acid catalyst is not particularly limited, and examples thereof include a known acid catalyst. Specific examples thereof include inorganic strong acids such as sulfuric acid, nitric acid, and hydrochloric acid.

These acid catalysts may be used alone or in combination of two or more.

As the acid catalyst, sulfuric acid is preferred from the viewpoint of low cost and performance improvement.

The blending ratio of the acid catalyst is, for example, 1 part by mass or more, preferably 5 parts by mass or more, for example, 20 parts by mass or less, preferably 100 parts by mass or less, based on 100 parts by mass of the carboxylic acid-modified lignin which has not been modified with phenol. It is 15 parts by mass or less.

Further, in the reaction between the carboxylic acid-modified lignin and the phenol, formaldehyde can be used in combination.

In the case of using formaldehyde, formaldehyde and carboxylic acid modified lignin and phenols will be copolymerized, formaldehyde will be methylene group due to dehydration condensation, and phenol modified carboxylic acid modified lignin (carboxylic acid modification) In the lignin-phenol resin, a phenol group is bonded via a methylene group.

In the case of using formaldehyde, the compounding ratio is 2 mol or less, preferably 1 mol or less, relative to the phenolic 1 molar.

Further, in the reaction of the carboxylic acid-modified lignin with the phenol, a solvent may be added as needed. Examples of the solvent include N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylammonium, and hexamethylphosphonium decylamine. And, preferably, N,N-dimethylformamide.

When the solvent is used, the amount thereof is, for example, 25 parts by mass or more, preferably 40 parts by mass or more, for example, 100 parts by mass or less, preferably 60 parts by mass, based on 100 parts by mass of the carboxylic acid-modified lignin. the following.

Further, in order to react the carboxylic acid-modified lignin with the phenol and, if necessary, with formaldehyde, for example, the components may be blended and heated in the above ratio.

The reaction temperature is, for example, 100 ° C or higher, preferably 110 ° C or higher, and for example 200 ° C or lower, preferably 150 ° C or lower. Further, the reaction time is, for example, 30 minutes or longer, for example, 3 hours or shorter.

By reacting a carboxylic acid-modified lignin with a phenol in this manner, a phenol-modified carboxylic acid-modified lignin (a phenolic modified substance of a carboxylic acid-modified lignin, a carboxy group) can be obtained. Acid modified lignin-phenol resin).

Further, after the completion of the reaction, the acid catalyst may be neutralized by adding a base as needed.

Further, unreacted components (unreacted phenols, etc.) may be removed and recovered by a known method such as filtration or distillation as needed. Further, the distillation conditions in the case of performing distillation are not particularly limited, and the temperature conditions are, for example, 150 ° C or higher, and the pressure conditions are, for example, 60 mmHg or less. Further, the unreacted components (unreacted phenols, etc.) recovered can be directly used in the next production.

Further, when a phenol-modified carboxylic acid-modified lignin is obtained as a solution (for example, in the case of adding an aqueous alkali solution, etc.), the solution may be added dropwise to an organic solvent such as hexane to The phenol-modified carboxylic acid modified lignin is recovered in the form of a precipitate.

Further, the phenol-modified carboxylic acid-modified lignin recovered in the form of a precipitate may be dissolved in an organic solvent or the like, and recovered again in the form of a precipitate, thereby modifying the phenol-modified carboxylic acid. The lignin is refined.

Further, the phenol-modified carboxylic acid-modified lignin (carboxylic acid-modified lignin-phenol resin) may be washed as needed. The washing method is not particularly limited. For example, water may be added to the phenol-modified carboxylic acid-modified lignin (carboxylic acid-modified lignin-phenol resin) and stirred. By such washing, impurities or salts generated by the above neutralization can be removed.

By using such a phenol-modified carboxylic acid-modified lignin (phenolic modified body of a carboxylic acid-modified lignin), heat resistance of an epoxy resin cured product (described later) can be improved.

Moreover, in the reaction of carboxylic acid-modified lignin (including phenol-modified carboxylic acid-modified lignin (the same applies hereinafter)) with epichlorohydrin, for example, in carboxylic acid-modified lignin The epichlorohydrin is combined and allowed to react under a known base catalyst.

The blending ratio of the carboxylic acid-modified lignin to the epichlorohydrin is in excess of 100 parts by mass of the carboxylic acid-modified lignin, and specifically, for example, 150 parts by mass or more, preferably 250 parts by mass. The above is, for example, 2,000 parts by mass or less, preferably 1,000 parts by mass or less.

The reaction temperature is, for example, 80 ° C or higher, preferably 90 ° C or higher, for example, 120 ° C or lower, preferably 110 ° C or lower. Further, the reaction time is, for example, 2 hours or longer, preferably 2.5 hours or longer, for example, 4 hours or shorter, preferably 3.5 hours or shorter.

Thereby, the glycidyl ether group is bonded to the carboxylic acid-modified lignin, whereby an epoxy resin can be obtained.

Further, in addition to the above, for example, the carboxylic acid-modified lignin may be bonded to epichlorohydrin by the following two stages of reaction to obtain an epoxy resin: first, a transfer catalyst is known between the phases (for example, four In the presence of a quaternary ammonium salt such as quaternary ammonium (TBAC), epichlorohydrin is added to the carboxylic acid-modified lignin in the above ratio, and then an alkali solution (such as an aqueous sodium hydroxide solution) is added thereto to make a closed loop. .

In this case, the reaction temperature of the first-stage reaction (reaction of epichlorohydrin to the carboxylic acid-modified lignin) is, for example, 60 ° C or higher, preferably 75 ° C or higher, for example, 90 ° C or lower. It is preferably 85 ° C or less. Further, the reaction time is, for example, 6 hours or longer, preferably 7 hours or longer, for example, 10 hours or shorter, preferably 9 hours or shorter.

Further, the reaction temperature of the second-stage reaction (closed-loop reaction) is, for example, 20 ° C or higher, preferably 35 ° C or higher, for example, 50 ° C or lower, preferably 45 ° C or lower. Further, the reaction time is, for example, 10 hours or longer, preferably 14 hours or longer, for example, 20 Below the hour, it is preferably 16 hours or less.

In the epoxy resin obtained in this manner, the bonding ratio of the carboxylic acid-modified lignin to epichlorohydrin is usually 100 parts by mass relative to the carboxylic acid-modified lignin, and the epichlorohydrin is 20 to 35 parts by mass.

In addition, the content of the carboxylic acid-modified lignin in the epoxy resin obtained in this manner is, for example, 70 parts by mass or more, preferably 75 parts by mass or more, based on 100 parts by mass of the total amount of the epoxy resin. For example, it is 85 parts by mass or less.

In addition, since such an epoxy resin is obtained by using a carboxylic acid-modified lignin, it is excellent in workability, and the heat resistance of the cured epoxy resin (described later) can be improved. Further, since such an epoxy resin is obtained by using a carboxylic acid-modified lignin, it is suitable for carbon neutralization, and the environmental load can be reduced.

2. Epoxy resin hardener

The epoxy resin hardener of the present invention comprises a carboxylic acid modified lignin.

Examples of the carboxylic acid-modified lignin include the above-mentioned carboxylic acid-modified lignin.

Further, the carboxylic acid-modified lignin is preferably used by extraction with an organic solvent.

By extracting the carboxylic acid-modified lignin with an organic solvent, the carboxylic acid-modified lignin can be purified, and the heat resistance of the cured epoxy resin (described later) can be improved.

Further, the carboxylic acid-modified lignin is preferably used by phenol modification.

When the carboxylic acid-modified lignin is phenol-modified, the heat resistance of the cured epoxy resin (described later) can be further improved.

Further, since such an epoxy resin hardener is obtained by using a carboxylic acid-modified lignin, it is excellent in workability and can be cured of an epoxy resin (post Said) the improvement of heat resistance. Further, since such an epoxy resin hardener is obtained by using a carboxylic acid-modified lignin, it is suitable for carbon neutralization, and the environmental load can be reduced.

3. Epoxy resin composition

The epoxy resin composition contains a main component composed of an epoxy resin and an epoxy resin hardener.

Examples of the epoxy resin include the epoxy resin of the present invention described above, and examples of the epoxy resin curing agent include the epoxy resin curing agent of the present invention.

Further, when the epoxy resin of the present invention is used as the epoxy resin, as the epoxy resin curing agent, for example, an aliphatic amine, an aromatic amine, a polyphenol compound, a novolac resin, an acid anhydride, or the like can be used. Epoxy resin hardener.

Further, when the epoxy resin curing agent of the present invention is used as the epoxy resin curing agent, as the epoxy resin, for example, a known epoxy resin such as a bisphenol epoxy resin or a novolac epoxy resin can be used. .

Further, as the epoxy resin, the epoxy resin of the present invention and the known epoxy resin may be used in an appropriate ratio, and as the epoxy resin curing agent, the above-mentioned epoxy resin hardener of the present invention may be Known epoxy resin hardeners are used in combination in an appropriate ratio.

It is preferable to use the epoxy resin of the present invention as an epoxy resin, and to use the above-mentioned epoxy resin hardener of the present invention as an epoxy resin hardener.

The formulation of the main agent (epoxy resin) and the epoxy resin hardener is such that the amine equivalent and/or the phenolic hydroxyl equivalent of the epoxy resin hardener and the epoxy equivalent of the main agent are substantially equal to ± 20%. Alternately formulated.

Further, as a method of blending, there is no particular limitation, for example, a main agent (ring The epoxy resin and the epoxy resin hardener are dissolved in a common solvent (for example, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, acetonitrile, etc.), and if necessary, a hardening accelerator (described later) is added, and then the solvent is volatilized. .

Further, when the main component (epoxy resin) and the epoxy resin hardener are dissolved in a solvent, heating may be performed as needed. The heating temperature is, for example, 40 ° C or higher, preferably 50 ° C or higher, for example, 70 ° C or lower, preferably 60 ° C or lower.

Further, in the epoxy resin composition, a curing accelerator can be added at an appropriate timing.

Examples of the curing accelerator include 2-ethyl-4-methylimidazole and derivatives thereof, 1-cyanoethyl-2-ethyl-4-methylimidazole, and derivatives thereof, and further examples thereof include dimethylbenzyl chloride. A tertiary amine such as an amine, a derivative of triphenylphosphine (TPP) (KALIBOR salt, etc.), and a known hardening accelerator.

In the case of blending the hardening accelerator, the blending ratio is, for example, 0.1 part by mass or more, preferably 0.2 part by mass or more, for example, 3 parts by mass, based on 100 parts by mass of the total amount of the epoxy resin and the epoxy resin hardener. Hereinafter, it is preferably 2 parts by mass or less.

Further, since such an epoxy resin composition uses carboxylic acid-modified lignin in an epoxy resin and/or an epoxy resin curing agent, it is excellent in handleability, and heat resistance of an epoxy resin cured product can be obtained. Sexual improvement.

4. Epoxy resin cured

The epoxy resin cured product can be obtained by hardening the epoxy resin composition.

Examples of the method for curing the epoxy resin composition include a method of injecting an epoxy resin composition into a known mold and heating it, or a method of performing vacuum hot press forming.

In the heating, the epoxy resin may be heated in one stage, or may be heated in multiple stages of two or more stages. It is preferred to heat the epoxy resin in two stages.

In this case, the heating temperature in the first stage is, for example, 140 ° C or higher, preferably 145 ° C or higher, for example, 160 ° C or lower, preferably 155 ° C or lower. Further, the heating time in the first stage is, for example, 1.5 hours or longer, preferably 2 hours or longer, for example, 3 hours or shorter, preferably 2.5 hours or shorter.

Further, the heating temperature in the second stage is, for example, 170 ° C or higher, preferably 175 ° C or higher, for example, 190 ° C or lower, preferably 185 ° C or lower. Further, the heating time in the second stage is, for example, 2.5 hours or longer, preferably 3 hours or longer, for example, 4 hours or shorter, preferably 3.5 hours or shorter.

Thereby, an epoxy resin cured product excellent in heat resistance can be obtained.

Moreover, since the cured epoxy resin is excellent in mechanical properties and electrical properties, and is obtained by using carboxylic acid-modified lignin, it is suitable for carbon neutralization, and the environmental load can be reduced.

Therefore, such an epoxy resin cured product is widely used in various industrial fields as an adhesive, a molding material, a structural material, a semiconductor sealing material, an electronic material, and the like.

In particular, it is preferably used in the field of electrical products, automobiles, and the like which are required to be suitable for carbon neutralization or heat resistance.

[Examples]

Hereinafter, the present invention will be described based on examples and comparative examples, but the present invention is not limited by the following examples. In the following description, "parts" and "%" indicate quality standards unless otherwise stated. Furthermore, the embodiments shown below The numerical value can be substituted for the corresponding numerical value (that is, the upper limit value or the lower limit value) described in the embodiment.

<Acetate modified lignin> Production Example 1 (no extraction/phenol-free modification)

100 parts by mass of corn forage stems and leaves were mixed with 95 parts by mass of acetic acid 1000 parts by mass and 3 parts by mass of sulfuric acid, and allowed to react under reflux for 4 hours. After the reaction, filtration is carried out to remove the pulp, and the pulp waste liquid is recovered. Then, the acetic acid in the pulp waste liquid was removed using a rotary evaporator, and concentrated to a volume of 1/10. Thereafter, 10 times (mass basis) of the concentrated liquid was added and filtered to thereby obtain a solid portion. The form of acetic acid modified lignin is obtained.

Production Example 2 (no extraction/phenolic modification)

Acetic acid modified lignin was obtained in the form of a solid portion by the same method as in Production Example 1.

Then, 100 parts by mass of acetic acid-modified lignin, 1000 parts by mass of p-cresol, and 11 parts by mass of 98% sulfuric acid were placed in a 300 mL three-neck separable flask equipped with a stirrer, a thermometer, and a cooling tube, and the mixture was heated while stirring. It was allowed to react at 130 ° C for 2.5 hours. Thereby, the lignin acetate was mixed with phenol and sulfuric acid, and liquefied within 20 minutes.

Then, the mixture was cooled to a temperature of 100 ° C or lower, and 45.3 parts by mass of a 20% aqueous sodium hydroxide solution was added to carry out neutralization. Then, the insoluble portion was removed by filtration, and thereafter, the obtained solution (filtrate) was added dropwise to its 20-volume amount of hexane to obtain a precipitate.

Then, the obtained precipitate is recovered by suction filtration, and It is dissolved in the minimum required (about 100 parts by mass) in tetrahydrofuran (THF). Then, the obtained solution was added dropwise to 20 volumes of hexane of tetrahydrofuran, and a precipitate was again obtained.

Then, the above filtration, the dissolution of tetrahydrofuran, and the dropwise addition of hexane were repeated, and the obtained precipitate was recovered by suction filtration.

Thereafter, the obtained precipitate was dried under conditions of 60 ° C and 40 mmHg for 15 hours, whereby a phenol modified body of acetic acid lignin was obtained.

Production Example 3 (with extraction/phenol-free modification)

Acetic acid modified lignin was obtained in the form of a solid portion by the same method as in Production Example 1.

Then, the obtained acetic acid-modified lignin was dissolved in an organic solvent (acetone), and the insoluble matter was removed by filtration. Thereafter, the organic solvent solution of the acetic acid-modified lignin is dried, whereby acetic acid-modified lignin (extracted product obtained by an organic solvent) is obtained.

Production Example 4 (with extraction/phenolic modification)

The acetic acid-modified lignin was subjected to phenol modification in the same manner as in Production Example 2 except that the acetic acid-modified lignin obtained in Production Example 3 (the extract obtained from the organic solvent) was used. Thereby, a phenolic modified body of acetic acid lignin (extracted product obtained by an organic solvent) is obtained.

Comparative Manufacturing Example 1 (no extraction/phenol-free modification)

Neutralize the wheat straw alkali-digested pulp waste liquid (black liquor), and then filter and borrow This obtains unmodified lignin in the form of a solid.

Comparative Manufacturing Example 2 (no extraction/phenolic modification)

The wheat straw alkali-digested pulp waste liquid (black liquor) is neutralized, and then filtered to obtain unmodified lignin in the form of a solid fraction.

Using this unmodified lignin, the unmodified lignin was subjected to phenol modification in the same manner as in Production Example 2. Thereby, a phenol modified body of unmodified lignin (lignin modified without carboxylic acid) was obtained.

Comparative Manufacturing Example 3 (with extraction/phenol-free modification)

Unmodified lignin was obtained in the form of a solid portion by the same method as Comparative Production Example 1.

Then, the obtained unmodified lignin was dissolved in an organic solvent (methanol), and the insoluble matter was removed by filtration. Thereafter, the organic solvent solution of the unmodified lignin is dried, whereby unmodified lignin (extract obtained by an organic solvent) is obtained.

Comparative Manufacturing Example 4 (with extraction/phenolic modification)

The unmodified lignin was subjected to phenol modification in the same manner as in Production Example 2 except that the unmodified lignin obtained in Comparative Example 3 (the extract obtained by the organic solvent) was used. Thereby, a phenol modified body of unmodified lignin (an extract obtained by an organic solvent) is obtained.

<Epoxy resin> [Example 1]

245 parts by mass of an acetic acid-modified lignin (extracted product obtained from an organic solvent) obtained in Production Example 3 was placed in a 1-liter four-necked flask equipped with a stirring motor, a thermometer, a dropping funnel, and a reflux cooling tube. 1850 parts by mass of epichlorohydrin and 27.4 parts by mass of tetramethylammonium chloride as an interphase transfer catalyst were added, and 0.9 parts by mass of water was added thereto, and the mixture was reacted at 80 ° C for 8 hours under a nitrogen stream.

Then, 50 g of a 20% by mass aqueous sodium hydroxide solution was added dropwise at 40 ° C, and stirred for 15 hours. Thereafter, the mixture was cooled to room temperature, and a 20% by mass aqueous acetic acid solution was added dropwise to neutralize it.

Then, the obtained solution was transferred to a separatory funnel, washed 5 times with 100 mL of ion-exchanged water, and then anhydrous magnesium sulfate was added to remove water.

Then, magnesium sulfate was removed by filtration, and the obtained solution (filtrate) was added dropwise to a 20-fold volume of a hexane/diethyl ether mixed solvent (mixing ratio of 7/3 (volume ratio)) of the solution. Precipitation is formed.

Thereafter, the obtained precipitate was recovered by suction filtration, and dried at 60 ° C and 40 mmHg for 15 hours, whereby an epoxy resin was obtained.

The epoxy equivalent (EEW) of the obtained epoxy resin was 280.

Further, the epoxy equivalent (EEW) was measured by the following method.

That is, the obtained epoxy resin (epoxidized lignin) was dissolved in chloroform, and 1,1',2,2'-tetrachloroethane (TCE) as a reference substance was added, and then ¹ H was measured. The NMR spectrum was calculated from the integrated intensity ratio of each peak by the following formula (the same applies hereinafter).

I _TCE : integral strength of 1,1',2,2'-tetrachloroethane (TCE)

I _epoxy : integral strength of epoxy groups

W _{epoxy resin} : the quality of epoxy resin (epoxidized lignin)

W _TCE : Quality of 1,1',2,2'-tetrachloroethane (TCE)

M _TCE : molecular weight of 1,1',2,2'-tetrachloroethane (TCE)

[Comparative Example 1]

An epoxy resin was obtained in the same manner as in Example 1 except that the unmodified lignin obtained in Comparative Production Example 3 (the extract obtained by the organic solvent) was used. The epoxy resin obtained had an epoxy equivalent of 290.

[Evaluation 1]

In order to study the properties of each epoxy resin, the epoxy resin and the epoxy resin hardener were formulated and hardened. Further, as the epoxy resin curing agent, a commercially available novolak resin (Phenolite TD-2131, manufactured by DIC Corporation) was used.

More specifically, first, an epoxy resin and an epoxy resin hardener are prepared such that the epoxy equivalent of the epoxy resin and the amine equivalent of the epoxy resin hardener and/or the phenolic hydroxyl equivalent are substantially equal. These are dissolved in tetrahydrofuran, and then a hardening accelerator (1-cyanoethyl-2-ethyl-4) is added in an amount of 0.5 parts by mass based on 100 parts by mass of the total amount of the epoxy resin and the epoxy resin hardener. -Methylimidazole), whereby a varnish is obtained. Then, the obtained varnish was cast on a film, and dried at 60 ° C for 2 hours, and tetrahydrofuran was removed, whereby an epoxy resin composition was obtained.

Thereafter, the mold was filled in Teflon (registered trademark), and heated at 150 ° C for 2 hours in vacuum pressing, followed by heating at 180 ° C for 3 hours, thereby hardening it. Furthermore, the epoxy resin composition melts upon heating and exhibits fluidity. Then harden.

The obtained epoxy resin cured product was evaluated by the following method. The results are shown in Table 1.

(1) Glass transition temperature

The measurement was carried out using dynamic viscoelastic analysis (DVA). As the measuring device, DMS-6100 manufactured by SII Nano Technologies Co., Ltd. was used. The size of the test piece was set to 10 mm × 40 mm × 2 mm. The measurement mode is a three-point bending mode, and the measurement conditions are set to air conditions, a temperature range of -100 ° C to 300 ° C, a temperature increase rate of 5 ° C / min, and a frequency of 1 Hz. The α relaxation peak temperature of the tan δ curve obtained thereby was set as the glass transition temperature (Tg).

<Epoxy resin hardener> [Embodiment 2]

The phenolic modified body of the acetic acid lignin obtained in Production Example 2 was set as an epoxy resin hardener.

[Example 3]

The phenol-modified body of the acetic acid-modified lignin (the extract obtained by the organic solvent) obtained in Production Example 4 was used as an epoxy resin hardener.

[Comparative Example 2]

The phenol modified body of the unmodified lignin obtained in Comparative Production Example 2 was set as an epoxy resin hardener.

[Comparative Example 3]

The phenol-modified body of the unmodified lignin (the extract obtained by the organic solvent) obtained in Comparative Production Example 4 was set as an epoxy resin hardener.

[Evaluation 2]

In order to study the properties of each epoxy resin hardener, the epoxy resin and the epoxy resin hardener were formulated and hardened. Further, as the epoxy resin, a commercially available bisphenol A type epoxy resin (trade name JER 828, manufactured by Mitsubishi Chemical Corporation) was used.

More specifically, first, an epoxy resin and an epoxy resin hardener are prepared such that the epoxy equivalent of the epoxy resin and the amine equivalent of the epoxy resin hardener and/or the phenolic hydroxyl equivalent are substantially equal. These are dissolved in tetrahydrofuran, and then a hardening accelerator (1-cyanoethyl-2-ethyl-4) is added in an amount of 0.5 parts by mass based on 100 parts by mass of the total amount of the epoxy resin and the epoxy resin hardener. -Methylimidazole), whereby a varnish is obtained. Then, the obtained varnish was cast on a film, and dried at 60 ° C for 2 hours, and tetrahydrofuran was removed, whereby an epoxy resin composition was obtained.

Thereafter, the mold was filled in Teflon (registered trademark), heated at 150 ° C for 2 hours in vacuum pressing, and then heated at 180 ° C for 3 hours, thereby It hardens. Further, the epoxy resin composition is cured by being melted upon heating and exhibiting fluidity.

The obtained epoxy resin cured product was evaluated by the same method as described above. The results are shown in Table 2.

<discussion>

With reference to the above evaluation 1 and evaluation 2, it was confirmed that an epoxy resin and an epoxy resin hardener obtained by using acetic acid-modified lignin can obtain an epoxy resin composition having a relatively high fluidity, and thus The epoxy resin composition and the cured product thereof are excellent in handleability.

Further, as described above with reference to the evaluations 1 and 2, it was confirmed that an epoxy resin and an epoxy resin curing agent obtained by using acetic acid-modified lignin can obtain a ring having a relatively high glass transition temperature and excellent heat resistance. Oxygen cured product.

[Evaluation 3]

The heat resistance of the cured epoxy resin was further evaluated by the following method. As the sample, an epoxy resin cured product obtained by using the epoxy resins of Example 1 and Comparative Example 1 was used. The results are shown in Table 3.

(2) 5% weight reduction temperature, 10% weight reduction temperature (heat decomposition resistance)

The measurement was carried out by thermogravimetric analysis (TGA). As the measuring device, TGA-50 manufactured by Shimadzu Corporation was used. More specifically, a powder sample obtained by using a gold trowel is weighed into a platinum tank in a weight of 3 to 4 mg at a temperature ranging from room temperature to 800 ° C, a temperature rising rate of 10 ° C/min, and a nitrogen gas flow. The measurement was carried out under the conditions of (20 mL/min). Based on the weight at 40 ° C, the temperature at which the weight was reduced by 5% was set to 5% by weight (T _d5 ), and the temperature at which 10% was decreased was set to 10% by weight (T _d10 ).

<discussion>

As can be seen from the above evaluation 3, it was confirmed that an epoxy resin obtained by using acetic acid-modified lignin can obtain an epoxy resin hardening having a 5% weight loss temperature and a 10% weight reduction temperature and excellent heat resistance. Things.

Furthermore, the invention described above is provided as an exemplified embodiment of the invention, which is merely illustrative and not limiting. Variations of the invention that are apparent to those skilled in the art are intended to be included within the scope of the appended claims.

(industrial availability)

The epoxy resin cured product obtained by using the epoxy resin and the epoxy resin hardener of the present invention is widely used in various industrial fields such as electronic components such as semiconductor sealing materials or coating materials and adhesives.

Claims (6)

An epoxy resin obtained by reacting at least a carboxylic acid-modified lignin with epichlorohydrin. The epoxy resin according to claim 1, wherein the lignin modified by the above carboxylic acid is phenol-modified. The epoxy resin according to claim 1, wherein the lignin modified by the carboxylic acid is extracted by an organic solvent. An epoxy resin hardener characterized in that it comprises a carboxylic acid modified lignin. The epoxy resin hardener according to claim 4, wherein the lignin modified by the carboxylic acid is phenol-modified. The epoxy resin hardener according to claim 4, wherein the lignin modified by the carboxylic acid is extracted by an organic solvent.