JPS5896074A - Novel hydrazide and latent curing agent for epoxy resin consisting of said compound - Google Patents

Abstract

NEW MATERIAL:The hydrazide of formulaI(R is H or methyl). USE:Latent curing agent for epoxy resin and a stabilizer for halogen-containing resin. It cures an epoxy resin rapidly at a low temperature, and has excellent storage stability. PROCESS:The compound of formulaIis prepared by reacting hydrazine hydrate with an addition reaction product of formula II(R' is alkyl) derived from 1mol of methionine hydantoin and 2mol of an acrylic acid ester or an addition reaction product of formula III drived from 1mol of methionine hydantoin, 1mol of a methacrylic acid ester an acrylic acid ester.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a latent curing agent for epoxy resins comprising a novel hydrazide and its compound.

Epoxy resins are cured using acid anhydride curing agents or amine curing agents, etc. In order to provide cured products with excellent mechanical, electrical, and chemical properties, epoxy resins are used as electrical insulating materials, various molded products, and adhesives. It is also widely prized as a paint, etc. However, epoxy resin compositions containing amine compounds have poor storage stability.
Furthermore, epoxy resin compositions containing acid anhydride curing agents are relatively stable at room temperature, but on the other hand, they have the disadvantage of requiring heating at considerably high temperatures and for long periods of time during curing. Therefore, it is common practice to shorten the curing time by using a curing accelerator such as a tertiary amine, a quaternary ammonium compound, or an organic metal complex salt. However, although curability is improved when a curing accelerator is added, storage stability is significantly impaired. Therefore, there is a strong demand for so-called latent curing agents that are stable at relatively low temperatures, do not gel, and quickly harden when heated. Several latent curing agents have been proposed so far, with representative compounds such as dicyandiazide,
Examples include dibasic acid hydrazide, boron trifluoride-amine adduct, guanamines, and melamine. However, although dicyandiamide, dibasic acid hydrazide, and guanamine have excellent storage stability,
In addition, boron trifluoride-amine adducts are highly hygroscopic and have a negative effect on the properties of the cured product. Until now, they have been used as latent curing agents that can be cured quickly at low temperatures. In addition, almost no compounds with excellent storage stability are known.

As a result of intensive studies to develop a latent curing agent that has low-temperature, fast curing properties and excellent storage stability, the present inventor found that
The present invention was completed based on the discovery that a hydrazide represented by the following general formula is an excellent latent curing agent that meets the purpose of the present invention.

(In the formula, R represents a hydrogen atom or a methyl group.) The hydrazide represented by the above general formula is a new substance that has not been described in any literature, and is an addition reaction product of methionine, 1 mole of dantoin, and 2 moles of acrylic ester. ) or the addition reaction product of methionine with 1 mole of hydantoin and 1 mole of methacrylic acid ester and 1 mole of acrylic acid ester (b) r-
It is easily obtained by reacting hydrazine hydrate.

[In formulas (a) and (b), R' represents an alkyl group] The addition reaction product (, ) of methionine hydantoin and acrylic ester is prepared by: in the presence of a basic catalyst such as potassium hydroxide; This is carried out by heating and refluxing methionine hydantoin and an acrylic acid ester in an amount of at least twice the mole of the hydantoin for several hours without a solvent or in a solvent such as methanol or ethanol.

Also, methionine hydantoin and methacrylic acid ester
The addition reaction product (b) with the acrylic ester is prepared by the following two-step reaction. First, in the presence of a basic catalyst such as potassium hydroxide, methionine hydantoin and a methacrylic acid ester in an amount equal to or more than the same mole relative to the hydantoin are mixed at a temperature of around 1,000 ml under pressure and in a solvent such as methanol or ethanol. By reacting for a period of time, an equimolar adduct of methacrylic acid ester represented by (υ) below can be obtained.

Next, the compound shown in (b') above and its equivalent
(b) can be obtained by heating and refluxing an acrylic ester of 5- or more esters in the presence of a basic catalyst without a solvent or in the above-mentioned solvent for several hours.

The acrylic ester and/or methacrylic ester to be added to methionine hydantoin is not particularly limited, but alkyl esters are usually used, and methyl esters are particularly practical. The amount of the basic catalyst present may be about 1% by weight based on methionine hydantoin. The addition reaction is usually carried out in the presence of an acrylic acid ester polymerization inhibitor such as hydroquinone.

Acrylic acid ester di-adduct of methionine hydantoin (2), or equimolar adduct of acrylic ester and methacrylic ester (b)
After heating and refluxing hydrazine hydrate in an amount of more than twice the mole of these adducts in a solvent such as methanol or ethanol for several hours, excess hydrazine hydrate and the solvent were removed, and hydrazine hydrate was dissolved in methanol, ethanol, water, etc. The desired hydrazide can be obtained by recrystallizing with a suitable solvent.

6- Conventionally known dibasic acid dihydrazides such as adipic acid dihydrazide, sebacic acid dihydrazide, and isophthalic acid dihydrazide are generally high melting point compounds of 180C or higher, and when a predetermined amount of one epoxy resin is blended, the curing temperature is 150C. or higher temperature is required. On the other hand, the new hydrazide of the present invention is a low melting point compound, and the one containing a certain amount of epoxy resin has good storage stability.
Moreover, it cures within 1 hour at a temperature of 120 to 130C, giving a colorless, transparent, and tough cured product. The amount of the latent curing agent of the present invention is in the range of 0.5 to 1.5 equivalents, preferably 0.7 to 1.2 equivalents of active hydrogen in the curing agent per equivalent of epoxy group in the epoxy resin. .

Epoxy resins applicable to the hydrazide of the present invention include those having one or more epoxy groups in one molecule, and include various well-known resins, such as glycidyl ethers of polyhydric phenols, Examples include glycidyl ethers of bisphenol A, glycidyl ethers of bisphenol 1, and polyglycidyl ethers of phenolformaldehyde resin.Furthermore, the hydrazide of the present invention is also effective as a stabilizer for halogen-containing resins. The heat stabilizing effect is especially remarkable when used in combination with metal soap.

Next, a method for synthesizing a hydrazide derived from methionine hydantoin and the usefulness of this compound as a latent curing agent for epoxy resins and a stabilizer for halogen-containing resins will be shown using Examples and Reference Examples.

Synthesis of Example 1 (When R=H) Methionine hydantoin (5-(2-(methylthio)ethyl)hydantoin) was added to a three-tube flask equipped with a stirrer. 41.3 f (0.48 mol) of methyl acrylate, 0.5 f of sodium hydroxide and 0.5 f of hydroquinone as a polymerization inhibitor.
51 was added thereto, and the mixture was heated under reflux for 5 hours while stirring. The reaction solution was dissolved in 200% of benzene, and after washing twice with 100% of water,
When benzene was removed under reduced pressure, a double molar adduct (-) of methionine-hydantoin with methyl acrylate was obtained at 58.
5 F was obtained.

The obtained ester 58.5 F and hydrazine hydrate (80
h) Dissolve 25.5 v in methanol 180 t,
The mixture was heated under reflux for 4 hours while stirring. Unreacted hydrazine hydrate and methanol were distilled off under reduced pressure from the reaction solution, and the residue was dissolved in 50+11/1 methanol and incubated overnight.

The precipitated crystals were collected by filtration, washed with methanol, and then dried under reduced pressure to obtain white crystals 33f.

Is the analysis value below? This is shown.

0 Melting point 151C O elemental analysis value Hibiki Tienshi CHN (%) Measured value 41.80 6.66 24.179
- Theoretical value (as C19"21Nll o4s) 41.6
1 6.40 24.26, electric field dex mass spectrum) lern/e 347 (M+H)+161(1(
-NT(,), 1320(CI(,l-8)0 nuclear magnetic resonance spectrum (heavy water solvent, DSS standard) δ(pprn
) 2.1 (3H,S,CI(,-8) around 2.3(
2H, m, CH-1-CT(,)3.5 (2H
,t,CH,-憇L N<o )3.8 (2H,
t, CH, -Shoichi-Nku38 )4.3 (IH,t
, CH, - sister? (Su) The crystal obtained from the above results is
It was confirmed that it was the target object.

Example 2 Synthesis of R (when R=-CH) In an autoclave equipped with electromagnetic stirring, 34.8 t (0.2 mol) of methionine hydantoin, 72 F methyl methacrylate (0.72 mol), water Potassium oxide 0.
5y and 0.52% of hydroquinone as a polymerization inhibitor were added, and after purging with nitrogen, the reaction was carried out at 150 to 160N for 5 hours under a stirring pestle. After cooling the reaction solution, apply benzene at 300mA! t
This was dissolved and washed, and the benzene layer was concentrated. When 300+x/ of methanol was added to this concentrated solution, a polymer of methyl methacrylate was precipitated, and after removing the polymer by filtration under reduced pressure, the filtrate was concentrated to dryness to form a methyl methacrylate heptaadduct (+31.9 F was obtained.

18.3 f (0,067 mol) of the obtained compound (b), 17.2 y (0,201 mol) of methyl acrylate, 0.2 V of potassium hydroxide and 0.31 of hydroquinone as a polymerization inhibitor were added, The mixture was heated under reflux for 5 hours while stirring. Add 100% of toluene to the reaction solution, and add 10% of toluene.
After washing 5 times with 0+n/water, toluene is distilled off 1 4
．． Add 99 m-=leak and 40 rnl of ethanol, heat under reflux for 4 hours, distill off the ethanol and unreacted hydrazine hydrate under reduced pressure, add 50 m of an 80 methanol aqueous solution to crystallize, and after filtration under reduced pressure, Dry white powder 11.69
I got it.

The analytical values of the above white powder are shown below.

0 Melting point 169-17 IC O elemental analysis value CHN C@ Measured value 43.62 6.35 23.70 Theoretical value (as CxeH>4Ns04S) 43.33
6.67 23.33, tFi desorption mass spectrum m/e, 361 (M + 1(')+ From the above results, it was confirmed that the obtained crystal was a single-purpose product.

Example 3 Curability and storage stability were evaluated using the blending ratios shown in Table 1.

1. Method for preparing samples for evaluation Each material was degassed and mixed under reduced pressure using a vacuum stirrer (Ishikawa Factory) V in the mixing ratios shown in Table 1 for 1 hour.

2 Evaluation of Curability 2-1) Differential thermal analysis The curing initiation temperature and peak temperature were measured.

Sample: Approximately 101i7 Reference material α-alumina Temperature increase rate sc/m1n 2-2) A sample was placed in a gear open at a constant temperature and its hardening state was observed.

-13- 3. Storage stability A sample was placed in a constant temperature bath at 40°C, and the number of days until fluidity disappeared was measured.

The results obtained are shown in Table 2.

Table 1 *1) Shell chemical source, bisphenol diglycidyl ether type liquid epoxy resin with epoxy equivalent of 175 to 210 -14- Results Table 2 From the results in Table 2, the hydrazides of the present invention have good storage stability and It will be understood that the curing properties are also excellent, and in particular, the curing properties are far superior to those of known latent curing agents.

Reference Example In order to examine the stabilizing effect of the hydrazides of the present invention on halogen-containing resins, a sheet with a thickness of 1 mm was prepared using a kneading roll at 160° C. using the following formulation, and a sheet with a thickness of 18 fltZ'
A thermal stability test was carried out at 1 liter of water.

The results are shown in Table 3.

Part by weight polyvinyl chloride (P=1050) 11 1.
00] (10 dioctyl phthalate
50 50 50 zinc stearate
t, o t, o
t.

Calcium stearate 1.0
+ , 0 1.0 Compound of general formula RlH
-0,5-Compound of general formula R; Cn
-105 Result Patent Applicant Ajinomoto Co., Ltd. Proceedings Masaru Yu, January 7, 1982 1 Indication of the case Patent Application No. 193065 of 1981 2 Title of the invention Epoxy comprising a novel hydrazide and its compound Date 1 Latent hardening 1 3 Relationship with the case of the person making the amendment Patent applicant address 5-8-5 Kyobashi-chome, Chuo-ku, Tokyo Amendment 1 Number of inventions increased from this 06 Subject of amendment δ of the invention in the specification To Ill explanation column 7 Yamatani 7E ) 'J,! :I TTE L f -f.
:) 3) 0 mentioned at the top of page 4 of the same book
Correct it to ``0''.

(4) Same book, page 5, line 7? "Also, methionine hydantoin" in this description is "also, methionine hydantoin"
I will correct it.

(5) 4-Town), No. 71'' (line 1 ['') of "adipate dihydrazide" as "adipate dihydrazide"
I will correct it.

(6) “(5-
First, correct "[2-(methylthio)ether]" to r(5-(22--(methylthio)ethyl)).

(7) “2.1 (
3H,S,CH*-8)J to r2.1 (3H.

s + CH! l　　　　　　　J.

that's all 3- 594-

Claims (1)

[Claims] A hydrazide represented by the general formula Ill (wherein R represents a hydrogen atom or a methyl group). (2) A latent curing agent for epoxy resins consisting of a hydrazide represented by the general formula (wherein R represents a hydrogen atom or a methyl group).