JPH0618857B2 - Curing agent for epoxy resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a curing agent for an epoxy resin, and more specifically, it has flexibility when cured and can produce a cured epoxy resin having excellent tear strength. A curing agent for an epoxy resin.

[Problems to be Solved by Conventional Techniques and Inventions] Generally, since epoxy resins have excellent properties,
Although it is often used as an adhesive, a molding material, etc., it is inferior in flexibility and has a drawback that it is easily cracked or broken by an impact or the like.

Conventionally, as a curing agent used for curing an uncured epoxy resin in order to impart flexibility to such an epoxy resin, an unsaturated acid anhydride adduct of isobutene oligomer (maleic anhydride adduct, etc.) is used. Is known (Japanese Patent Laid-Open No. 59-36128).

However, although the above-mentioned curing agent imparts excellent flexibility to the cured product of the epoxy resin, it has a disadvantage that the tear strength is lowered.

[Means for solving problems]

The present inventor has conducted earnest studies to solve the above-mentioned inconvenience, to impart excellent flexibility to a cured epoxy resin, and to develop a curing agent that does not cause a decrease in tear strength.

As a result, it was found that the purpose can be achieved by using the polyol compound together with the unsaturated acid anhydride adduct of isobutene oligomer. The present invention has been completed based on such findings. That is, the present invention provides a curing agent for an epoxy resin containing an unsaturated acid anhydride adduct of an isobutene oligomer and a polyol compound as main components.

The unsaturated acid anhydride adduct of isobutene oligomer used in the present invention is obtained by reacting isobutene oligomer with unsaturated acid anhydride, wherein isobutene oligomer is obtained by polymerizing isobutene or isobutene and a small amount of n-. It is preferable to use liquid polybutene having a number average molecular weight of 100 to 2500, which is obtained by copolymerizing butene. This isobutene oligomer is, for example, from a residue obtained by extracting butadiene from a C ₄ fraction produced during naphtha decomposition as a raw material, using aluminum chloride or the like as a catalyst, under the conditions of 5 to 130 ° C. and 1 to 22 kg / cm ² G. It can be produced by polymerization.

On the other hand, examples of the unsaturated acid anhydride include maleic anhydride, citraconic anhydride, itaconic anhydride, aconitic anhydride, and the like.

In reacting the isobutene oligomer with the unsaturated acid anhydride, an appropriate temperature, for example, 180 to 300 ° C.
In the range of preferably 200 to 250 ° C. for an appropriate time, for example 2 to 20 hours, preferably 5 to 10 hours.

In the curing agent of the present invention, it is necessary to use a polyol compound together with the unsaturated acid anhydride adduct of the isobutene oligomer obtained by the above reaction. The proportion of the polyol compound used may be appropriately determined depending on the type, the type of the unsaturated acid anhydride adduct of the isobutene oligomer, the type of the epoxy resin to be cured, etc. 2 for department
It may be selected in the range of 0 to 200 parts by weight, preferably 50 to 150 parts by weight.

In addition, although there are various types of this polyol compound, a hydroxyl group-containing liquid diene polymer or its hydride is preferably used, and it is also preferable to use both in combination.

Here, the hydroxyl group-containing liquid diene polymer has a number average molecular weight of 300 having a hydroxyl group in the molecule or at the terminal of the molecule.
.About.25,000, preferably 500 to 10,000, of the liquid diene polymer is used. Here, the content of the hydroxyl group is usually 0.1 to 10 meq / g, preferably 0.3 to 7 meq / g. These liquid diene polymers have 4 to 1 carbon atoms.
There are diene polymers and diene copolymers of 2, as well as copolymers of these diene monomers and α-olefinic addition polymerizable monomers having 2 to 22 carbon atoms. Specific examples thereof include butadiene homopolymer, isoprene homopolymer, butadiene-styrene copolymer, butadiene-isoprene copolymer, butadiene-acrylonitrile copolymer, butadiene-2-ethylhexyl acrylate copolymer, butadiene-n-octadecyl acrylate copolymer and the like. These liquid diene polymers can be produced, for example, by reacting a conjugated diene monomer in a liquid reaction medium in the presence of hydrogen peroxide with heating.

The hydride of the hydroxyl group-containing liquid diene polymer can be obtained by hydrogenating the hydroxyl group-containing liquid diene polymer in the presence or absence of a solvent using a hydrogenation catalyst.

As the other polyol compound, any of a primary polyol, a secondary polyol and a tertiary polyol may be used. Specifically, 1,2-propylene glycol; dipropylene glycol; 1,2-butanediol; 1,
3-butanediol; 2,3-butanediol; 1,2
-Pentanediol; 2,3-pentadiol; 2,5
-Hexanediol; 2,4-hexanediol; 2-
Ethyl-1,3-hexanediol; cyclohexanediol; glycerin; N, N-bis-2-hydroxypropylaniline; N, N'-bishydroxyisopropyl-2-methylpiperazine; at least propylene oxide adduct of bisphenol A Mention may be made of low molecular weight polyols containing a hydroxyl group attached to one secondary carbon.

Further, as the polyol, ethylene glycol having no hydroxyl group bonded to secondary carbon; 1,3-propylene glycol; 1,4-butanediol; 1,5 pentanediol; 1,6-hexanediol and the like can also be used. . Furthermore, polyoxypropylene glycol; polyester polyol; polyoxytetramethylene glycol; polycarbonate diol and the like can also be used.

As the polyol compound other than the above hydroxyl group-containing liquid diene polymer, diol is usually used, but triol or tetraol may be used, and its molecular weight is 5
It is in the range of 0 to 10,000.

The curing agent of the present invention contains an unsaturated acid anhydride adduct of the above isobutene oligomer and a polyol compound as main components, and if desired, it may further contain 2,4 or 4 as a curing accelerator.
6-Tris (diethylaminomethyl) phenol; dimethylaminomethylphenol; 2-methylimidazole; 2-ethyl-4-methylimidazole and the like can also be added.

By the way, as the uncured epoxy resin to which the curing agent of the present invention is applied, any known epoxy resin can be arbitrarily selected and has at least two epoxy groups per molecule. Resin, epoxy novolac resin, bisphenol A-epichlorohydrin resin,
A polyfunctional epoxy resin, an aliphatic epoxy resin, an alicyclic epoxy resin, etc. can be used. A typical example of these epoxy resins is a resin represented by the following general formula, in which the reaction of bisphenol and epichlorohydrin is more obtained, (In the formula, n is an integer of 0 or 30 or less.) Generally, n is 2 or 3 or less and an epoxy equivalent of 170 to 30.
Those having 0 are preferred. Further, diluents such as glycidyl ethers of aliphatic alcohols having 3 to 10 carbon atoms such as butyl glycidyl ether and allyl glycidyl ether and other commercially available epoxy diluents can be added to these epoxy resins. The diluent can be used usually in an amount of 20 parts by weight or less of the epoxy resin.

In curing the uncured epoxy resin using the curing agent of the present invention, the amount used is not particularly limited,
In short, the amount is sufficient as long as the uncured epoxy resin is cured. Generally, it is 1-250 parts by weight, preferably 5-200 parts by weight, based on 100 parts by weight of the uncured epoxy resin.

There are no particular restrictions on the procedure and conditions for the curing treatment, and any conventional method may be used. For example, an appropriate amount of the curing agent of the present invention is added to an uncured epoxy resin, and various curing accelerators are added as necessary, and the amount is 0.2 to 2 at 50 to 150 ° C.
If the curing reaction is performed for 0 hours, a cured epoxy resin having the desired physical properties can be obtained. As the curing agent of the present invention used in the curing treatment, a reaction product obtained by previously heating and mixing both the unsaturated acid anhydride adduct of isobutene oligomer and the polyol compound can be used.

〔Example〕

Next, the present invention will be described in more detail based on examples.

Production Example 1 (Production of Isobutene Oligomer) 5 g of aluminum chloride was placed in a 500 ml autoclave and decompressed with a vacuum pump, and then 50 g of n-butane was added as a solvent. After stirring to sufficiently disperse the aluminum chloride, 200 g of raw material (isobutene 42
wt%, butene-12.18 wt%, n-butane 40 wt% mixture) was added dropwise over 20 minutes. After dropping, the mixture was reacted at 10 ° C. for 2 hours.

After the reaction is completed, unreacted gas and n-butane are removed,
300 g of water was added under ice cooling to decompose aluminum chloride. Then, the mixture was extracted 3 times with 500 ml of n-hexane, and then n-hexane was distilled off to obtain 80 g of isobutene oligomer having a number average molecular weight of 350.

Further, by changing the reaction conditions, isobutene oligomers of 2 to 5 mer were obtained.

Production Example 2 (Production of unsaturated acid anhydride adduct of isobutene oligomer) A predetermined amount of maleic anhydride and a predetermined amount of the isobutene oligomer obtained in Production Example 1 were charged into a 1-volume stainless steel autoclave and heated at 230 ° C. The reaction was carried out for 5 hours.

After completion of the reaction, the mixture was allowed to cool, the contents were transferred to a round bottom flask, and the pressure was reduced by a vacuum pump to obtain four kinds of adducts having a predetermined boiling point range. The results are shown in Table 1.

Production Example 3 (Production of Polyol Compound) Isobutene 20 was placed in a stainless steel pressure-resistant reaction vessel of 1 volume.
0 g, 16 g of 50 wt% hydrogen peroxide aqueous solution and 100 g of n-butyl alcohol were added, 120 ° C., maximum pressure 8
The polymerization reaction was performed at kg / cm ² G for 2 hours.

After the reaction was completed, the reaction solution was taken out, shaken in a separating funnel together with 600 g of water, and allowed to stand for 3 hours to separate an oil layer.

Then, this oil layer was treated under a reduced pressure of 2 mmHg at 100 ° C. for 2 hours to distill off the solvent, unreacted monomers and low-boiling components, and yield 68% by weight of liquid polyisoprene having a hydroxyl group at the molecular chain end. Got with. This product has a number average molecular weight of 2150, an OH value of 0.96 meq / g and a viscosity of 56 poise /
It was 30 ° C.

Examples 1 to 8 and Comparative Examples 1 to 4 100 g of an epoxy resin was placed in a container, and a predetermined amount of an unsaturated acid anhydride adduct of an isobutene oligomer obtained in Production Example 2 and a polyol compound was added thereto as a curing agent. , 0.5 g of 2,4,6-tris (diethylaminomethyl) phenol as a curing accelerator was added and mixed,
After quickly degassing, the mixture was poured into a silicone mold and cured in an oven at 130 ° C. for 2 hours to obtain a cured epoxy resin. The physical properties of this cured product are shown in Table 2.

[Effects of the Invention] As described above, when an uncured epoxy resin is cured using the curing agent of the present invention, the resulting epoxy resin cured product has a large tear strength and sufficient flexibility. It

Therefore, the curing agent of the present invention can be effectively used in various molding materials, adhesives, electric insulating materials such as printed circuit boards, and the like together with uncured epoxy resin.

Claims (2)

[Claims] 1. A curing agent for an epoxy resin containing an unsaturated acid anhydride adduct of isobutene oligomer and a polyol compound as main components. 2. A polyol compound is added in an amount of 20 to 100 parts by weight based on 100 parts by weight of an unsaturated acid anhydride adduct of an isobutene oligomer.
The curing agent for an epoxy resin according to claim 1, which is compounded in an amount of 200 parts by weight.