JPH01304112A - Latent curing agent for epoxy resin - Google Patents

Abstract

PURPOSE:To improve storage stability at ordinary temp., fast curing property by heating when mixed with an epoxy resin and to improve the heat resistance and toughness of the obtd. cured product by incorporating four specified kinds of repeating units. CONSTITUTION:The title curing agent consisting of a polymeric substance contg. 10-99mol% unit of formula I, 1-90mol% unit of formula II, 0-90mol% unit of formula III and 0-90mol% of formula IV is obtd. by compounding a monomer (A) providing a repeating unit of formula I [wherein R1-2 are each H, a (cyclo) alkyl or an aryl] (e.g., styrene), a monomer (B) providing a repeating unit of formula II ]wherein R3-4 are each R1; R5 is a (cyclo)alkylene, a phenylene or -R11-; R11 is -0-, a cycloalkylene or a phenylene; and Y is an org. group contg. a sec. and/or tert. nitrogen] [e.g., N-(N,N-dimethylaminoethyl)maleimide], a monomer (C) providing a repeating unit of formula III (wherein R6-7 are each R1) (e.g., maleic acid anhydride) and a monomer (D) providing a repeating unit of formula IV (wherein R8-10 are each R1).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a latent curing agent for epoxy resins, and an epoxy resin composition comprising the latent curing agent and an epoxy resin. More specifically, it can be mixed with epoxy resin to improve its storage stability at room temperature.

The present invention also relates to a latent curing agent and a composition comprising the same, which rapidly cures when heated to provide a cured product with excellent heat resistance and toughness. Furthermore, the present invention provides an industrially advantageous manufacturing method for the curing agent.

[Prior art] Epoxy resin has excellent curing properties, and the obtained cured product has excellent properties such as adhesiveness, mechanical properties, chemical resistance, and electrical properties, so it is used in a wide range of industrial fields. has been done.

However, when using an epoxy resin, it is necessary to mix two components: an epoxy resin and a curing agent. However, since the mixture begins to harden in a short time at room temperature, its use requires frequent and complicated mixing operations or the need to store the mixture at low temperatures, which is a practical hassle. ing.

Recognizing that these drawbacks greatly limit the uses of epoxy resins, we aim to solve these drawbacks by creating products that are mixed with epoxy resins, have excellent storage stability at room temperature, and are resistant to heating. Attempts have been made to develop curing agents that cure quickly.

This kind of W + arsenic agent.

It is known as a latent curing agent, and some are already in practical use.

Typical latent curing agents include, for example, dicyandiamide. ! ! Acid hydrazide, Lewis acid
Amine complexes are known, but dicyandiamide and organic acid hydrazide have the disadvantage of high practical curing temperature, although they have poor storage stability, and Lewis acid-amine complexes have high hygroscopicity and poor storage stability. 2 Furthermore,
These curing agents are low molecular weight substances and have the disadvantage of relatively high toxicity. As a latent curing agent, an adduct formed by reacting a compound having a tertiary amino group with an epoxy compound is also known.
No. 6, No. 60-4524, No. 31-14822
No. 8, No. 61-171722, U.S. Patent No. 3. 75
6. No. 984, 4. 066, 625 No. 4
, 268, 656, etc., but
Cured products cured using these curing agents generally have poor heat resistance, so they were often used in combination with other curing agents1.Furthermore, these compounds have been used as anionic polymerization type curing catalysts for epoxy resins. It is a compound in which a functional tertiary amino group is added to the end of a linear epoxy resin, but the catalytic ability or curing rate of the latent curing agent depends on the molecular weight of the curing agent when the amount of curing agent added is constant. It will depend on. Therefore, for example, when the curing agent improves or modifies the properties of the obtained cured product, the curing rate and the physical properties of the cured product simultaneously depend on the amount of the curing agent added, which may cause problems.

Acid anhydrides are known to act as curing agents for epoxy resins in the presence or absence of Lewis bases, and the resulting cured products have excellent heat resistance.For example, copolymers of styrene and maleic anhydride is composed of the copolymer and an epoxy resin because the maleic anhydride residue has the ability to harden the epoxy resin as mentioned above, and the copolymer itself has a high glass transition temperature. It is known that the cured product has excellent heat resistance (for example, JP-A No. 58-64259). However, the curing speed of the copolymer is slow in the absence of a Lewis base, making it difficult to reach a practical curing temperature. It does not function as a curing agent, has poor storage stability in the presence of Lewis bases, and exhibits no latent potential.

[Problem to be solved by the invention 1 As mentioned above, there are several known latent curing agents for epoxy resins, but all of them are inferior in function as curing agents, or It did not improve the physical properties of the cured product.

The purpose of the present invention is to provide a curing agent for epoxy resins that has latent properties and improves the physical properties of cured products, particularly heat resistance, and to provide an epoxy resin composition comprising the curing agent. Furthermore.

Another purpose of the present invention is to provide an industrially advantageous manufacturing method for the curing agent.

[Means for Solving the Problems] That is, in the present invention, 9 molecules contain 10 to 99 mol% of repeating units represented by general formula [1], and 1 to 99 mol% of repeating units represented by general formula [II]. 90 mol%, 0 to 90 mol% of repeating units represented by the general formula [■], and 0 to 90 mol% of repeating units represented by the general formula [1'V'l] as an epoxy resin. It has been found that when used as a curing agent, an epoxy resin composition can be obtained that has excellent storage stability, a fast curing speed at low temperatures, and a cured product that has excellent heat resistance. Furthermore.

In the present invention, a polymer substance having 10 to 99 mol% of repeating units represented by the general formula CI] and 1 to 90 mol% of repeating units represented by the general formula Cm] and an amine compound are screw extruded. The present invention was completed based on the discovery that the latent curing agent can be industrially advantageously produced by supplying the latent curing agent to a machine and causing the reaction.

General formula [! 1 General formula [II] ~ General formula Cm] General formula [■R6R7R8R
9 1l 1 1 - c -c - -c -c - 11; 1 000 ONO RIO However, R1, R2, R3, R4, R6, R7, R8, R
9 and RIO are a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group, and R5 is an alkylene group, a cycloalkylene group, a phenylene group, or -R11-
(However, R11 represents a 10-1 cycloalkylene group or a phenylene group) is an alkylene group bonded to
Y represents an organic group containing secondary and/or tertiary nitrogen. Specific examples of the organic group include general formulas [V], [VI],
There are [■ko and [■ko].

General formula [■] General formula [VI] General formula [■
General formula [■] However, R12 and R13 are hydrogen atoms and alkyl groups.

Represents a cycloalkyl group, aryl group or alkyne group, but both R12 and R13 must not be hydrogen atoms, H represents a hydrogen atom, A represents an alkyl group, cycloalkyl group or aryl group, X represents an oxygen atom or -N- (however, R14 is an alkyl group, cycloalkyl group or aryl group) &Hbl C+ d
, e and f are O or an integer of 1 or more, and A
+ b = 4°c + d = 3. e X f
≠0.

In the latent curing agent molecule, the repeating units of general formula [1] and general formula [IV] are units that are not directly related to the curing reaction of the epoxy resin, and the repeating units of the general formula [■] are units that are not directly related to the curing reaction of the epoxy resin. It is a unit containing secondary or tertiary nitrogen that functions as a mold curing agent, and the repeating unit of the general formula [ml is a unit containing an acid anhydride group that functions as a polyaddition type curing agent for epoxy resin.

Of the latent curing agent! 11 There are no particular restrictions on the manufacturing method. 2 For example, polymerization to form the general formula [! ] (monomer [II), monomer [■]) giving a repeating unit of the general formula [■], - giving a repeating unit of the general formula [III] Monomer [ml] and general formula [I
It can be produced by radical copolymerization of a monomer (monomer [IV]) that provides the repeating unit of [V].

Monomer [! The specific properties 11 include ethylene, propylene, l-butene, isobutylene, cyclopentene,
Olefins such as cyclohexene, halogenolefins such as vinyl chloride and vinylidene chloride.

Fatty acid vinyl esters such as vinyl acetate, styrene.

Styrenes and vinyl ethers such as α-methylstyrene, vinyltoluene, and butylstyrene.

Conjugated dienes such as butadiene, isoprene, chlorobrene, methyl acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate.

Cyclohexyl acrylate, decyl acrylate, octadecyl acrylate, hydroxyethyl acrylate, methoxyethyl acrylate.

Acrylic acid esters such as glycidyl acrylate.

Methyl methacrylate, ethyl methacrylate.

Butyl methacrylate, hexyl methacrylate.

Cyclohexyl methacrylate, octadecyl methacrylate, hydroxyethyl methacrylate.

Methacrylic acid esters such as methoxyethyl methacrylate and glycidyl methacrylate, nitriles such as acrylonitrile and methacrylaterile, acrylamides, vinyl ketones such as methyl vinyl ketone and phenyl vinyl ketone, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid, etc. These can be used alone or in combination.

The monomer [U] is a monomer containing an imide group.

Specific examples include N-(N,N-dimethylaminoethyl)maleimide, N-(N,N-diethylaminoethyl)maleimide, N-(N,N-dimethylaminopropyl)maleimide, N-piperidinoethyl maleimide, N-(4-piperidylethyl)maleimide, N-picolylmaleimide.

These can be used alone or in combination.

Specific examples of monomer [ml] compounds include maleic anhydride, methylmaleic anhydride, 1,2-dimethylmaleic anhydride, ethylmaleic anhydride, and phenylmaleic anhydride.

Specific examples of compounds of monomer [IV] include maleimide,
N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-hexylmaleimide, N-cyclohexylmaleimide, N-decylmaleimide, N-phenylmaleimide, N-tolylmaleimide, N-(chlorophenyl)maleimide, N- (bromophenyl)maleimide.

Examples include N-(dibromophenyl)maleimide.

Monomer [1], [II], [I[I] and [I
There is no particular restriction on the method of copolymerization of V], and any known method of radical copolymerization can be applied.

Another method for producing the latent curing agent of the present invention is a method in which a copolymer of monomer [II and monomer [m] is reacted with an amine compound to imidize the acid anhydride residue. I can give an example. The imidization reaction between a polymer substance having an acid anhydride residue in the polymer chain and an amine compound is well known.9
For example, Special Publication No. 61-26.936 or Special Publication No. 62
According to the method disclosed in No. 8456, a polymeric substance and an amine compound are reacted to produce a target latent curing agent having an imide group.

Examples of amine compounds used when introducing the repeating unit of the general formula [1] in the imidization reaction are dimethylaminoethylamine, ethylaminoethylamine, diethylaminoethylamine, methylaminopropylamine,
Dimethylaminopropylamine, diethylaminopropylamine, dibutylaminopropylamine, dimethylaminoethoxypropylamine, lauryl aminopropylamine, jetanolaminopropylamine, N-aminoethylpiperidine, N-7minoethyl-4-pipecoline, N-amino Ethylmorpholine.

N-aminopropyl-2-pipecoline, N-aminopropylmorpholine, 4-7minomethylbiperidine, 1-amino-4-methylpiperazine, N-aminopropylpiperazine, 2-aminopyridine.

3-aminopyridine, 4-aminopyridine, 2-picolylamine, 3-picolylamine, 4-picolylamine,
Examples include 1-aminoethylimidazole, 1-amituprobylimidazole, and 1-aminohexylimidazole.

Further, examples of amine compounds used when introducing the repeating unit of general formula [IV] in an imidization reaction include ammonia, methylamine, and ethylamine.

Propylamine, butylamine, hexylamine.

Examples include cyclohexylamine, decylamine, octadecylamine, aniline, toluidine, naphthylamine, chlorophenylamine, dichlorophenylamine, bromophenylamine, and dibromophenylamine.

The imidization reaction can be carried out in any manner, and the desired imidized product can be synthesized by reacting a polymeric substance containing an acid anhydride group with the above-mentioned amine compound in the presence or absence of a solvent. I can do it. In particular, when a melt kneader such as a screw extruder, Banbury mixer, or co-kneader is used as a reactor to perform the imidization reaction in the molten state,
Since the reaction can be carried out without using a solvent, it is industrially advantageous in that the reaction apparatus can be small-scale and energy consumption can be small. In particular, when a screw extruder is used as a melt kneader, it is easy to control the residence time or reaction temperature, and it is also easy to devolatilize, so unreacted amines that cause a decrease in storage stability can be efficiently removed. This is advantageous because it is achieved.

There are no particular restrictions on the screw extruder used for the imidization reaction, and any single-screw extruder or multi-screw extruder can be used, but a twin-screw extruder that rotates in the same direction or in different directions is particularly suitable for excellent extrusion operability. Preferably used. The extruder preferably has a vent for devolatilization (1) Usually, the pressure of the vent is reduced using a vacuum pump. The raw materials are fed into the extruder through the same or separate inlet (feedro), and in particular when feeding a low boiling point amine compound, they can be fed under pressure with a metering pump. The feeder does not necessarily need to be provided at the base of the screw; it is also possible to supply the polymeric substance from the screw base and supply the amine compound into the molten polymeric substance from the feeder provided in the middle of the barrel. be. Also,
When raw materials are fed from the same feeder, two or more types of raw materials can be mixed in advance using a mixer, etc., although the operating conditions of the screw extruder are arbitrary.

The reaction temperature is 100-400°C, preferably 200-35°C.
It is preferable to control the temperature in the range of 0°C.9 The reaction time is 20°C.
The inside of the extruder may be replaced with an inert gas such as nitrogen or argon for the purpose of preventing oxidative deterioration of the two reactants.

The imidization reaction does not require a particular catalyst, but if one is used, trimethylamine or triethylamine is used.

Tributylamine, N,N-dimethylaniline.

Tertiary amines such as N,N-diethylaniline are preferred.

The imidization reaction can be carried out in a solution state using two reaction vessels.9 Although there are no particular restrictions on the reaction method, a specific example would be a polymer substance containing an acid anhydride residue and the above-mentioned amine. The compound is dissolved in a solvent and the core temperature is 50 to 250.
React at ℃ for 2-20 hours. Although a catalyst is not necessarily required, the above-mentioned tertiary amine catalyst can also be used.
Reaction solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, ethers such as tetrahydrofuran and l,4-dioxane, and aromatic hydrocarbons such as toluene and xylene.

Dimethylformamide, dimethyl sulfoxide.

Examples include N-methyl-2-pyrrolidone.

Monomer [in ml, maleic acid, methylmaleic acid, l,2-dimethylmaleic acid, ethylmaleic acid,
Propyl maleic acid, phenylmaleic acid, aconitic acid, fumaric acid, methyl fumaric acid, 1:2-dimethyl fumaric acid, ethyl fumaric acid.

A polymer substance obtained by copolymerizing an unsaturated dicarboxylic acid such as propyl fumaric acid, phenyl fumaric acid, itaconic acid, etc. with monomer [1] is imidized with the above-mentioned amine compound to obtain the desired latent curing agent. It is also possible to synthesize

The latent curing agent of the present invention contains 10 to 99 mol% of repeating units represented by the general formula [Natsu], 1 to 90 mol% of repeating units represented by the general formula [I], and 1 to 90 mol% of repeating units of the general formula [II1F]. A polymer substance having 0 to 90 mol% of repeating units represented by general formula [1] and 0 to 90 mol% of repeating units represented by general K CIV ], where 10 mol% of repeating units of general formula [1] %, or the repeating unit of general formula [I[] is 90
If the content exceeds 99 mol%, the storage stability of the composition obtained by mixing the polymer substance with the epoxy resin will be poor, and if the repeating unit of general formula [1] exceeds 99 mol%, or ]
If the repeating unit of formula [■] or [TV] exceeds 90 mole%, it is not suitable because the curing speed of the composition is slow.
A more preferred composition, which is not suitable because the strength of the cured product obtained by curing the composition is weak, is a composition in which the repeating unit represented by the general formula [1] is 30 to 80 mol % and the repeating unit is represented by the general formula [II]. 5 to 60 mol% of repeating units, 0 to 50 mol% of repeating units represented by the general formula [ml, and 0 to 50 mol% of repeating units represented by the general formula [■].

The latent curing agent of the present invention has a glass transition temperature of 50 to 250.
℃, preferably in the range of 70 to 200℃. If the glass transition temperature is less than 50"C, the storage stability of the composition obtained by mixing with the epoxy resin will be low, and if it exceeds 250℃, the composition will deteriorate. curing speed is slow.

Furthermore, the latent curing agent has a molecular weight of 400 to 200.0.
00. The molecular weight is preferably in the range of 1,000 to 100,000.9 If the molecular weight is less than 400, the storage stability of the composition obtained by mixing with the epoxy resin is low;
If it exceeds 00,000, the curing speed of the composition will be slow.The molecular weight here refers to fEfl based on polystyrene determined by gel permeation chromatography.
Average molecular weight.

The latent curing agent of the present invention is mixed with an epoxy resin to provide an epoxy resin composition having latent properties, but the epoxy resin used is not particularly limited.

Known liquid or solid epoxy resins are optionally used. Examples of suitably used epoxy resins include glycidyl ether type epoxy resins such as bisphenol A diglycidyl ether type and novolak glycidyl ether type, hexahydrophthalic acid glycidyl ester,
Glycidyl ester type epoxy resins such as dimer acid glycidyl ester, glycidyl amine type epoxy resins such as triglycidyl isocyanurate, tetraglycidyl diaminodiphenylmethane, epoxidized polybutadiene,
Linear aliphatic epoxy resins such as epoxidized soybean oil, 3.4
-Epoxy-6-methylcyclohexylmethylcarboxylate and other alicyclic epoxy resins.

The amount of the latent curing agent of the present invention used is preferably 0.1 to 50 parts by weight per 100 parts by weight of the epoxy resin, O,
If it is less than 1 part by weight, the curing speed of the epoxy resin composition will be slow, and if it exceeds 50 parts by weight, the strength of the cured product will be low.

In addition to the latent curing agent and epoxy resin of the present invention, the epoxy resin composition of the present invention may contain other known curing agents, such as acid anhydrides, dicyandiamide, etc. , diaminomaleonitrile, imidazole compound, dibasic acid dihydrazide, polyamine salt,
Guanamines.

Melamines, polyphenol necks, etc.

Furthermore, the epoxy resin composition of the present invention contains known additives for epoxy resins, such as ductility imparting agents.

Impact modifiers, fillers, diluents, thixotropic agents, pigments, solvents, erasers, leveling agents.

It may contain a tackifier or the like.

[Function] The composition of the present invention has excellent latent properties, so it is easy to handle, has a fast curing speed, and the cured product has excellent heat resistance, so it can be used in electrical applications such as paints, adhesives, FRP, and electronic device sealing materials. , electronic equipment parts.

Suitable for use in various industrial parts, etc.

[Example] The present invention will be explained in more detail with reference to Examples below.
All parts and percentages used in the Examples and Comparative Examples are by weight.

In addition, the method for determining various properties is as per the revision.

Curing agent molecule m: Using a sample of tetrahydrofuran solution, the average molecular weight of ff1fl based on polystyrene was determined by gel permeation chromatography.

Glass transition temperature of curing agent: Determined by differential scanning calorimetry using DSC-200 manufactured by Seiko Electronics Industries, Ltd.

Curing temperature: A mixture of an epoxy resin and a curing agent was placed in an aluminum container, and after being left in a constant temperature bath for 1 hour, the presence or absence of curing was observed. The temperature of the constant temperature bath is 80℃, 100℃,
The temperatures were 120°C, 140°C and 160°C.

Pot life: A mixture of an epoxy resin and a curing agent was placed in a glass container, left in a constant temperature bath at 40° C., and the time until gelatinization was measured.

Curing time: Thermochimica Acta,
R, L, M disclosed in 36 (+980) 121131
According to the method of Il Ier et al., a mixture of an epoxy resin and a curing agent was placed in a DSC device maintained at a constant temperature, and the time at which the exotherm ended was measured.

Glass transition temperature of cured product: A mixture of an epoxy resin and a curing agent was cast at 120°C or 160°C for 6 hours. The obtained test piece was measured using a dynamic viscoelasticity automatic measuring machine Rheopyblon DDV-2/3 manufactured by Orientic Co., Ltd.
-Measured by EA 6 frequency 110Hz, heating rate 2
°C/min.

Shear strength of cured product: ASTM D]002-64
The tensile shear strength was determined using a method based on . Curing temperature: 120°C or 160°C, curing time: 6 hours.

Moreover, the origin of the sample used is as follows.

SMA resin: ARCOCheIIlical Co
mpany Ltd, P! A copolymer of styrene and maleic anhydride and the copolymerization ratio of styrene and maleic anhydride are as follows.

5MA100O = 1: l 5MA2000 = 2: l 5MA3000 = 3: 1 Bisphenol A type epoxy resin: Ebiko (manufactured by Yuka Shell Epoxy Co., Ltd.) 828. Epoxy equivalent 1
84-194°Cresol novolak epoxy resin: Sumiepoxy ESCN-195X manufactured by Sumitomo Chemical Co., Ltd.

Epoxy equivalent: 190 to 205° Phenol novolak resin: Showa Kobunshi Co., Ltd. Showol BR -556, phenol equivalent: 103° Example 1. Comparative Example 1 30 parts of 5MA100O was charged into an autoclave, and while nitrogen gas was flowing, 70 parts of cyclohexanone was added to dissolve the primary 5MA100O in an amount equivalent to 80 mol% of the maleic anhydride residue in 5MA100O. , N-dimethylaminopropylamine was added, the can was sealed, and the reaction was allowed to proceed at 140° C. for 6 hours with stirring. After cooling, the two reaction solutions were yellow and transparent.

The reaction solution was poured into 30 times the volume of ether to recover the polymer, which was vacuum dried at 80°C to obtain a pale yellow powder.

When the nitrogen content in the obtained polymer was determined by elemental analysis, it was confirmed that almost 100% of the added raw material amine had reacted. Further, the amount of raw material amine remaining in the purified polymer was quantified using a gas chromatography mass spectrometer and found to be 0.5 ppm.

The obtained powder was further finely ground in a mortar and sieved through a 200-mesh sieve, and the material passing through the mesh was used as a sample (sample No. I).

Similar experiments were conducted by changing the type and amount of the resin, solvent, and amine compound used, and various curing agents were synthesized (Sample No.
, 2-16).

The obtained curing agent powder was mixed with bisphenol A type epoxy resin and subjected to a curing test.

The synthesis conditions of the curing agent are summarized in Table 1, and the properties and performance of the obtained curing agent are summarized in Tables 2 and 3.

Example 1 and Comparative Examples 1 to 9 It can be seen that the curing agent of the present invention provides a latent thermosetting resin composition when mixed with an epoxy resin. Furthermore, it can be seen that the latent curing agent has a fast curing speed, and the cured product has excellent heat resistance.

Example 2 The curing agent of Sample 1 in Table 1 was dissolved in methyl ethyl ketone to form a 10% solution. Add 25 parts of this solution to a silane coupling agent (γ-glycidoxyprobyltrimethoxysilane).
50 parts of silica powder and 1501 parts of methyl ethyl ketone! After adding β and thoroughly mixing, the solvent was evaporated to dryness. The obtained powder was vacuum dried at 120° C., then ground in a mortar and sieved through a 200-mesh sieve, and the material passing through the mesh was used as a sample.

70 parts of the obtained silica powder was mixed with 20 parts of cresol novolak epoxy resin and 10 parts of phenol novolac resin on a hot plate at 90°C to prepare a sample.

The curing time of the obtained sample was 23 minutes at 175°C.

Example 3 While flowing nitrogen gas into an autoclave, 65 parts of styrene and 50 parts of cyclohexanone were charged.

The temperature was raised to 83°C while stirring. After the contents reached 83°C, 35 an of maleic anhydride, 0 an of benzoyl peroxide. A solution of 1 part and t-dodecylmercaptan dissolved in 150 parts of degassed cyclohexanone was continuously added to the system over 8 hours.

Two hours after the start of continuous addition, the temperature of the contents was raised to 103°C, and after the continuous addition was completed, the temperature was raised to 115°C to complete polymerization.

9 parts of added t-dodecyl mercaptan.

It was divided into 4 or 6 parts.

The polymerization rate determined by gas chromatography was 95% for styrene and 99% for maleic anhydride.

The polymerization solution was cooled to room temperature, and N was added in an amount corresponding to 80 mol % based on the maleic anhydride residues in the polymer.

Add N-dimethylaminopropylamine and incubate at 60℃ for 2 hours.
The reaction was further continued at 140° C. for 4 hours.

After the reaction solution was cooled, it was poured into 30 times the volume of methanol to recover the polymer, which was then vacuum dried at 80°C.

The obtained powder was ground in a mortar and sifted through a 200-mesh sieve, and the material passing through the mesh was used as a sample.

The obtained curing agent was mixed with a bisphenol A type epoxy resin and the curing characteristics were evaluated. The results are summarized in Table 4.

As is clear from Table 4, the obtained mixture of curing agent and epoxy resin is a latent thermosetting resin composition.

Example 4 The reaction was carried out using a screw extruder.

The screw extrusion mode used has a ventro.

It is a co-rotating twin-screw extruder, and the ratio of the effective length of the screw to the outer diameter, so-called L/D, is 30.

Hopper 〇 is located at the base of the screw, and raw materials are fed into the hopper mouth by a screw-type quantitative feeder. The raw materials used were pre-mixed using a Henschel mixer.

There is one ventro, and it is 700mmHH with a vacuum pump.
The pressure is reduced to

The reaction temperature was 280°C, and the residence time was 2 minutes.

The discharged material from the extruder is crushed by a pelletizer.

After being further finely ground in a ball mill, it was sieved through a 200-mesh sieve, and the material that passed through the mesh was used as a sample.

The obtained curing agent was mixed with a bisphenol A type epoxy resin in the same manner as in Example 1 and subjected to various evaluations.

The reaction conditions are summarized in Table 5, and the performance evaluation results of the epoxy resin composition are summarized in Table 6.

Let it react inside the screw extruder! ! The remaining curing agent has excellent storage stability and curing properties similar to the curing agent produced in the two-reaction can, and v! It can be seen that the chemical properties are also excellent. Furthermore, compared to the reaction using nine reaction vessels, the reaction using a screw extruder has many industrial advantages, such as a shorter reaction time and a simpler single reaction operation, and there is no need to separately purify the product.

Example 5. Comparative Example 2 Bisphenol A epoxy resin 10 used in Example 1
Part 0 and sample No. prepared in Example 4.

The curing agent No. 17 was further mixed with various other curing agents to prepare an epoxy resin composition and its performance was evaluated.

The results are summarized in Table 7.9 The curing agent of the present invention is as follows.

When used in combination with other curing agents with high curing temperatures, it provides an epoxy resin composition with excellent storage stability and curing performance.

Table 4 Table 5 Table 6 Table 7 DICY: Dicyandiamide PYRO: Pyrogallol 7g/120: 120°C/6 hours Glass transition temperature of cured product [Effects of the invention]As explained above It is a latent curing agent that has significantly improved storage stability, which was a drawback of curing agents for resins. Furthermore, the latent curing agent of the present invention overcomes the drawbacks of conventional latent curing agents, such as high curing temperature and low heat resistance of the cured product. Therefore, the composition comprising the latent curing agent and the epoxy resin of the present invention eliminates the complexity of handling, which is a disadvantage of conventional epoxy resins, and provides a cured product with high heat resistance at a low curing temperature. I can do it.

Patent applicant: Denki Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] 1. 10 repeating units represented by the general formula [I] in the molecule
~99 mol%, 1~99 mol% of repeating units represented by general formula [II]
90 mol%, 0 to 0 repeating units represented by general formula [III]
90 mol% and repeating units represented by general formula [IV] from 0 to
A latent curing agent for epoxy resin consisting of a polymeric substance having 90 mol%. General formula [I] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ General formula [II] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ General formula [III] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ General formula [IV] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ However, R1, R2, R3, R4, R6, R7, R8, R
9 and R10 are a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group, and R5 is an alkylene group, a cycloalkylene group, a phenylene group, or -R11-(
However, R11 is an alkylene group bonded to -O-, a cycloalkylene group or a phenylene group, and Y
represents an organic group containing secondary and/or tertiary nitrogen. 2. A latent epoxy resin composition comprising an epoxy resin and the latent curing agent according to claim 1. 3. 10 repeating units represented by the general formula [I] in the molecule
99 mol % and a polymeric substance having 1 to 90 mol % of repeating units represented by the general formula [III] and the amine compound are fed to a screw extruder and reacted. A method for producing a latent curing agent for epoxy resin.