JPH0717888B2 - Epoxy resin adhesive - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel epoxy adhesive.

More specifically, it relates to an epoxy adhesive having excellent heat resistance.

[Prior Art] Epoxy resin adhesives have various excellent characteristics.
For example, (1) Universal adhesiveness-formed by reaction of an OH group or epoxy group in the epoxy resin molecule with a curing agent containing active hydrogen.
The OH groups may form hydrogen bonds with the surface of the adhesive, and the adherents with active hydrogen such as nylon and various celluloses form primary (chemical) bonds with the epoxy groups.

(2) Low shrinkage-Since no volatile by-products are generated during the reaction curing, the shrinkage rate is small, and the linear shrinkage rate of the unmodified epoxy resin cast product having a thickness of 1/2 inch is 0.05 to 0.1. %.

(3) High strength-excellent mechanical strength.

(4) Chemical resistance-Excellent alkali resistance and moisture resistance.

(5) Excellent weather resistance.

(6) Excellent electrical properties.

(7) Modification and modification can be freely performed by selecting the main agent and the curing agent.

For example, 1) Moisture resistance, 2) Peel strength, 3) Reaction speed, 4) Curing at room temperature or higher, 5) Adhesion to wet surface, 6) Flame resistance, 7) One-component or two-component combination Is possible.

Utilizing many of these features, metal, plastic,
It is used for bonding a wide range of materials such as wood, glass, concrete and ceramics.

As described above, the epoxy resin-based adhesive is used in many fields, but the required physical properties are becoming diverse depending on each field.

In particular, there is an increasing demand for heat resistance in adhesives for structural materials in the automobile industry, aerospace industry, etc., and adhesives for electronic parts in the electric field.

However, the current epoxy resin adhesives have not yet satisfied this requirement.

[Problems to be Solved by the Invention] In view of these circumstances, the present inventors have diligently studied, and
The inventors have found that an epoxy resin adhesive having excellent heat resistance and electrical characteristics can be obtained by using the novel epoxy resin having a cyclohexane skeleton proposed in JP-A-60-166675, and completed the present invention.

(Structure of the Invention) That is, the present invention provides (A) general formula (I) <Wherein R ¹ is an organic compound residue having ¹ active hydrogen, n1, n2 ... nl are 0 or an integer of 1 to 100, respectively, and the sum thereof is 1 to 100; 1 is 1 to 100 Represents the integer of A
Is a cyclohexane skeleton having a substituent, represented by the following formula, X is -CH = CH _2, R ² is any one of H, an alkyl group, a carboalkyl group and a carboallyl group, Containing at least one or more in the resin represented by (I)> (Epoxy resin based coating composition (B) Epoxy resin curing agent).

Next, the present invention will be described in detail.

In the epoxy resin represented by the formula (I) of the present invention,
R is an organic residue having active hydrogen, and examples of the organic compound having active hydrogen as a precursor thereof include alcohols, phenols, carboxylic acids, amines and thiols.

The alcohol may be a monohydric alcohol or a polyhydric alcohol.

For example, methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol and other aliphatic alcohols, aromatic alcohols such as benzyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol,
1.3 butanediol, 1.4 butanediol, pentanediol, 1.6 hexanediol, neopentyl glycol, oxypivalic acid neopentyl glycol ester, cyclohexanedimethanol, glycerin, diglycerin, polyglycerin, trimethylolpropane, trimethylolethane, pentaerythritol, There are polyhydric alcohols such as dipentaerythritol.

Examples of phenols include phenol, cresol, catechol, pyrogallol, hydroquinone, hydroquinone monomethyl ether, bisphenol A, bisphenol F, 4,4'-dihydroxybenzophenone, bisphenol S, phenol resin and cresol novolac resin.

Carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, fatty acids of animal and vegetable oils, fumaric acid, maleic acid, adipic acid, dodecane diacid, trimetritic acid, pyromellitic acid, polyacrylic acid, phthalic acid, isophthalic acid, terephthalic acid. Etc. Moreover, compounds having both a hydroxyl group and a carboxylic acid, such as lactic acid, citric acid, and oxycaproic acid, can also be mentioned.

As amines, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, dodecylamine, 4,4'-diaminodiphenylmethane, isophoronediamine, toluenediamine, hexamethylenediamine, xylenediamine, Examples include diethylenetriamine, triethylenetetramine, ethanolamine and the like.

Examples of thiols include mercapto such as methyl mercaptan, ethyl mercaptan, propyl mercaptan, and phenyl mercaptan, mercaptopropionic acid or polyhydric alcohol ester of mercaptopropionic acid, for example, ethylene glycol dimercaptopropionic acid ester, trimethylolpropane trimercaptopropionic acid, Examples thereof include pentaerythritol pentamercaptopropionic acid.

Further, as the compound having active hydrogen, polyvinyl alcohol, polyvinyl acetate partial hydrolyzate, starch, cellulose, cellulose acetate, cellulose acetate butyrate, hydroxyethyl cellulose,
There are acrylic polyol resin, styrene allyl alcohol copolymer resin, styrene-maleic acid copolymer resin, alkyd resin, polyester polyol resin, polyester carboxylic acid resin, polycaprolactone polyol resin, polypropylene polyol, polytetramethylene glycol, and the like.

The compound having active hydrogen may have an unsaturated double bond in its skeleton, and specific examples thereof include allyl alcohol, acrylic acid, methacrylic acid, 3-cyclohexenemethanol, tetrahydrophthalic acid and the like. is there.

The unsaturated double bonds in these compounds can also be in their epoxidized structure.

N ₁ , n ₂ ... nl in the general formula (I) are 0 or 1 to 1, respectively.
Is an integer of 100. The sum is 1 to 100, but if it is 100 or more, it becomes a resin having a high melting point, is difficult to handle, and cannot be practically used.

l is an integer from 1 to 100.

Among the substituents X of A in formula (I), It is essential to include at least one or more The larger the amount, the more preferable.

In particular The less, the more preferable.

That is, in the present invention, the substituent X is Is the main one.

The epoxy resin represented by the formula (I) used in the adhesive of the present invention can be produced by a ring-opening polymerization of 4-vinylcyclohexene-1-oxide with an organic compound having active hydrogen as an initiator. It can be produced by epoxidizing an ether resin, that is, a polycyclohexene oxide polymer having a vinyl group side chain with an oxidizing agent such as peracid.

4-Vinylcyclohexene-1-oxide is obtained by partially epoxidizing vinylcyclohexene obtained by the dimerization reaction of butadiene with peracetic acid.

When polymerizing 4-vinylcyclohexene-1-oxide in the presence of active hydrogen, it is preferable to use a catalyst.

As the catalyst, amines such as methylamine, ethylamine, propylamine and piperazine, organic basic acids such as pyridine and imidazole, organic acids such as formic acid, acetic acid and propionic acid, inorganic acids such as sulfuric acid and hydrochloric acid, sodium methylate Alkalates of alkali metals such as, KOH, alkalis such as NaOH, BF ₃ , ZnCl ₂ , AlCl ₃ , SnCl _{4 and} other Lewis acids or their complexes, triethylaluminum,
An organometallic compound such as diethylzinc can be used.

These catalysts can be used in the range of 0.01 to 10%, preferably 0.1 to 5% with respect to the starting material. The reaction temperature is -70 to 200 ° C, preferably -30 ° C to 100 ° C.

The reaction can also be carried out using a solvent. A solvent having active hydrogen cannot be used as the solvent.

That is, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, benzene, toluene,
Aromatic solvents such as xylene, ethers, aliphatic hydrocarbons, esters and the like can be used.

In order to produce a novel epoxy resin of the formula (I), which is the main component of the adhesive of the present invention, by epoxidizing the polycyclohexene oxide polymer having a vinyl group side chain thus synthesized, a peracid or hydro Either of the peroxides can be used.

As the peracids, formic acid, peracetic acid, perbenzoic acid, trifluoroperacetic acid and the like can be used.

Of these, peracetic acid is a preferable epoxidizing agent because it is industrially available at low cost and has high stability.

As the hydroperoxides, hydrogen peroxide, tertiary butyl hydroperoxide, cumene peroxide and the like can be used.

A catalyst may be used in the epoxidation, if necessary. For example, in the case of peracid, an alkali such as sodium carbonate or an acid such as sulfuric acid can be used as a catalyst. In the case of hydroperoxide, a mixture of tungstic acid and caustic soda is hydrogen peroxide, or an organic acid is hydrogen peroxide,
Alternatively, molybdenum hexacarbonyl can be used with tertiary butyl hydroperoxide to obtain a catalytic effect.

The epoxidation reaction is carried out by adjusting the presence or absence of solvent and the reaction temperature according to the physical properties of the equipment and raw materials. Depending on the conditions of the epoxidation reaction, the epoxidation of the olefin bond and the substituents in the raw material Or generated substituents As a result of side reaction with an epoxidizing agent such as peracetic acid, a modified substituent is generated and is contained in the target compound.

Substituent in target compound And the ratio of the three modified substituents is determined by the type of epoxidizing agent, the molar ratio of the epoxidizing agent-olefin bond, and the reaction conditions. When the epoxidizing agent is peracetic acid, the modified substituent mainly has a structure as shown below and is generated from the generated epoxy group and acetic acid by-produced.

The target compound can be taken out from the reaction crude liquid by ordinary chemical engineering means such as concentration.

As the curing agent used for the epoxy resin adhesive of the present invention, known curing agents used for epoxy resins can be used, and amines, polyamide resins, acid anhydrides, polymercaptan resins, novolac resins, dicyandiamide, and three An amine complex of boron fluoride and the like are included.

Here, the amines include the following.

Aliphatic polyamines such as diethylenetriamine, triethylenetetramine, menthenediamine, metaxylylenediamine, bis (4-amino-3-methylcyclohexyl) methane, etc., and adducts of said aliphatic polyamines with known epoxy compounds, and reaction with acrylonitrile Compounds, reaction products with ketones, aromatic polyamines such as metaphenylenediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, diaminodiphenyl sulfide, and adducts of said aromatic polyamines with known epoxy compounds,
Secondary and tertiary amines such as tris (dimethylaminomethyl) phenol, piperidine, imidazole and its derivatives, and salts thereof.

The polyamide resin includes a reaction product of a fatty acid such as fatty acid, dimer acid and trimer acid with an aliphatic polyamine.

The acid anhydride includes the following.

Phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic acid dianhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride Acid anhydrides such as succinic anhydride, todecenyl succinic anhydride, and succinic anhydride, and mixtures of the acid anhydrides.

Novolac resins include low molecular weight resinous products made by condensation of phenol or a mixture of phenol and cresol, dihydroxybenzene and formaldehyde.

The amine complex of boron trifluoride includes a complex of boron trifluoride with a low molecular weight amine compound such as monoethylamine, piperidine, aniline, butylamine, dibutylamine, cyclohexylamine, dicyclohexylamine, tributylamine, and triethanolamine. Be done.

Other curing agents include boron tetrafluoride, phosphorus hexafluoride, diazonium salts of superstrong acids such as arsenic hexafluoride, iodonium salts, bromonium salts, and sulfinium salts. Further, among these curing agents, aliphatic polyamines, aromatic polyamines, polyamide resins, polymercaptan resins can be mixed and used at an arbitrary ratio, and used alone or in combination with a curing accelerator for the purpose of adjusting the curing speed. You can also do it. Here, as the curing accelerator, the second and third curing accelerators are used.
Amines can be used.

The acid anhydride can be used as it is, but it is also possible to use a curing catalyst and a curing accelerator together for the purpose of adjusting the curing rate and improving the physical properties of the cured product. Here, as the curing catalyst, the secondary and tertiary amines and tin octylate as the curing accelerator, water, alcohols such as ethanol, propanol, isopropanol, cyclohexanol, and ethylene glycol, acetic acid, propionic acid, succinic acid. ,
Carboxylic acids such as hexahydrophthalic acid and amines having active hydrogen such as ethylenediamine and diethylenetriamine.

The novolac resin may be used alone or in combination with a curing catalyst for the purpose of adjusting the curing rate. Here, the curing catalyst is the second or third type.

Dicyandiamide can be used alone or in combination with a curing catalyst for the purpose of adjusting the curing rate. Here, the curing catalyst is the secondary and tertiary amines.

The amine complex of boron trifluoride may be used alone or in combination with a curing rate adjusting agent for the purpose of adjusting the curing rate.
Here, the curing rate adjustor may be any one that can be used for conventional epoxy resins, and specifically, for example, carboxylic acids, amine acids, metal acetylacetone complexes, titanium, tin, and other metals. The organic metal compounds, glycols, organic boron compounds, etc.

The epoxy resin adhesive in the present invention can be used as a mixture with other epoxy resins as long as the characteristics of the epoxy resin represented by the general formula (I) are not impaired.
Any other epoxy resin may be used as long as it is generally used as an adhesive, and examples thereof include epibis type epoxy, bisphenol F epoxy, novolac epoxy resin and the like.

In addition, the epoxy resin-based adhesive of the present invention may contain the additives used in ordinary adhesives.

For example, silica, kaolin, inorganic fillers such as titanium white, iron, zinc, aluminum, graphite, gold,
Conductive materials such as silver, adhesion promoters such as silane coupling agents, titanium coupling agents, grindyl ester of dimer acid, synthetic rubber modified epoxy resin, towability imparting agents such as terminal carboxy polybutadiene, colloidal silica, etc. A thixotropic agent can be added.

[Effects of the Invention] The epoxy resin-based adhesive of the present invention obtained as described above can be a one-component type or a two-component type depending on the selection of a curing agent, and can be cured at room temperature or by heat. .

A wide range of materials, such as metal, glass, paper, wood, and porcelain, can be selected for the attachment. Since it has excellent heat resistance and electric characteristics, it is particularly excellent as an adhesive for electronic parts, automobiles, and aircraft structural materials.

The present invention will be described below with reference to examples.

Synthetic Example 1. 58 g (1 mol) of allyl alcohol, 868 g (7 mol) of 4-vinylcyclohexene-1-oxide and 4.7 g of BF ₃ etherate were mixed at 60 ° C., and 4-vinylcyclohexene-1- was analyzed by gas chromatography. The reaction was continued until the conversion rate of oxide became 98% or more. Ethyl acetate was added to the obtained reaction crude liquid and washed with water, and then the ethyl acetate layer was concentrated to obtain a viscous liquid.

Found in the raw material in the infrared absorption spectrum of the product
Absorption by epoxy groups at 810, 850 cm ^-1 has disappeared, there is absorption by ether bonds at 1080, 1150 cm ^-1 , gas chromatography analysis shows that allyl alcohol in the product is a trace amount, It was confirmed from the infrared absorption spectrum that this compound has a structure represented by the following formula since the compound has an OH group absorption at 3450 cm ^-1 .

(N = average 7) 429 g of this compound was dissolved in ethyl acetate and charged into a reactor, to which 395 g of peracetic acid was added dropwise as an ethyl acetate solution over 2 hours. During this time, the reaction temperature was kept at 40 ° C. After the addition of peracetic acid was completed, the mixture was aged at 40 ° C. for 6 hours.

Ethyl acetate was added to the reaction crude liquid, and the mixture was washed with alkaline water containing 416 g of sodium carbonate and then well with distilled water.

The ethyl acetate layer was concentrated to give a viscous transparent liquid. This compound had an oxirane oxygen content of 9.27% and showed characteristic absorption due to an epoxy group at 1260 cm ^-1 in an infrared absorption spectrum. Further, absorption by a residual vinyl group was observed at 1640 cm ⁻¹ , and 492 g of this compound was reacted with 395 g of peracetic acid in the same manner as in Synthesis Example 1 to obtain a viscous transparent liquid.

This compound had an oxirane oxygen content of 9.27% and showed characteristic absorption due to an epoxy group at 1260 cm ^-1 in an infrared absorption spectrum. Further, absorption at 1640 cm ^{-1 due} to residual vinyl group was observed, and 492 g of this compound was obtained as in Synthesis Example 1.
Was reacted with 395 g of peracetic acid to obtain a viscous transparent liquid.

This compound had an oxirane oxygen content of 9.27% and showed characteristic absorption due to an epoxy group at 1260 cm ^-1 in an infrared absorption spectrum. Furthermore the absorption by the residual vinyl group observed in 1640 cm ^-1, OH group in 3450 cm ^-1, the 1730 cm ^-1 It is confirmed that the present invention has the structure of the general formula (1) (R ₁ : glycidyl group or allyl group, n = average 7, including a group in which 1 part of acetic acid is added to an epoxy group). did.

Synthesis Example-2 By the same operation as in Synthesis Example 1, trimethylolpropane 134 was used.
1863 g of 4-vinylcyclohexene-1-oxide was reacted to obtain a viscous liquid product.

In the infrared absorption spectrum of the product, the absorption due to the epoxy groups at 810 and 850 cm ⁻¹ found in the raw material disappeared, the absorption due to the ether bond existed at 1080 and 1150 cm ⁻¹ , and the NMR analysis revealed that It was confirmed that the compound had a structure represented by the following formula.

Further, as in Synthesis Example-1, 573 g of this compound and 387 g of peracetic acid
Was carried out to obtain a viscous transparent liquid.

This compound had an oxirane oxygen content of 9.03% and showed characteristic absorption due to an epoxy group at 1260 cm ^-1 in the infrared absorption spectrum. Furthermore the absorption by the residual vinyl group observed in 1640 cm ^-1, OH group in 3450 cm ^-1, the 1730 cm ^-1 Therefore, the present invention relates to the structure of the general formula (I) (R ₁ : trimethylolpropane residue 1 = 3, n ₁ , n ₂ , n).
₃ = 5 on average, including 1 part of a group in which acetic acid is added to an epoxy group).

Examples-1 to 2 Comparative Example-1 As the epoxy resin and the epi-bis type epoxy resin obtained in Synthesis Examples 1 and 2, Epicoat 1004 manufactured by Yuka Shell Co., Ltd. and methylhexahydrophthalic anhydride as a curing agent were mixed. And a viscous adhesive was obtained.

Using this adhesive, the tensile shear adhesive strength of a cold rolled steel plate was measured.

Curing conditions: 150 ° C for 4 hours Measuring conditions: 20 ° C, 150 ° C Composition: Curing agent / epoxy resin (equivalent ratio) It can be seen that the adhesive of the present invention has excellent adhesive strength at high temperatures.

Examples-3 to 6 Comparative Example-2 The epoxy resins obtained in Synthetic Examples 1 and 2 were compared to the epi-bis type epoxy resin, which was added to Epicoat 828 manufactured by Yuka Shell Co., Ltd., in the following composition to compare the adhesive strength. .

Curing conditions: 40 ° C. for 24 hours Curing agent: Fuji Chemical Co., Ltd., Thomide 255 Composition: Curing agent / epoxy resin (equivalent ratio) = 0.9 It can be seen that the adhesive of the present invention has excellent adhesive strength.

Claims (1)

[Claims] 1. (A) General formula (I) <Wherein R ¹ is an organic compound residue having ¹ active hydrogen, n1, n2 ... nl are 0 or an integer of 1 to 100, respectively, and the sum thereof is 1 to 100; 1 is 1 to 100 Represents the integer of A
Is a cyclohexane skeleton having a substituent, represented by the following formula, X is -CH = CH _2, R ² is any one of H, an alkyl group, a carboalkyl group and a carboaryl group, An epoxy resin-based adhesive comprising the epoxy resin (B), a curing agent for an epoxy resin, which comprises at least one or more in the resin represented by (I).