JPH0231732B2 - EHOKISHIJUSHISOSEIBUTSU - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a one-component epoxy resin composition,
More specifically, the present invention relates to an epoxy resin composition that has good storage stability, curability, and adhesion between materials of the same or different types, and maintains excellent flexibility over a long period of time. When epoxy resin is used as an adhesive, it has the characteristics of high shear strength and strong adhesion to metals, but has the disadvantage of low peel strength, so it is mainly used between metal materials in the fields of aircraft, building materials, etc. It is not suitable for semi-structural adhesive applications used in adhesive sealing. For the purpose of improving peel strength, various flexibility-imparting agents and plasticizers are added, flexible plastics or rubbers are mixed in, and highly reactive functional groups such as hydroxyl groups, carboxylic acid groups, and isocyanate groups are added. A method has been proposed in which a modified epoxy resin obtained by reacting a prepolymer having the following with an epoxy resin is used alone or in combination with an unmodified epoxy. These methods have had problems such as insufficient flexibility or gradual loss of flexibility over time. Furthermore, when a polysulfide-modified epoxy resin obtained by reacting a polysulfide compound having a thiol group at the molecular end with an epoxy resin is used alone or mixed with an unmodified epoxy resin, sufficient flexibility cannot be obtained. It is also known to be effective with little change in flexibility over a long period of time. A polysulfide-modified epoxy resin or a mixture thereof with an unmodified epoxy resin is highly preferred in terms of workability if it is used as a one-component adhesive composition containing a so-called latent curing agent. One-component compositions can be stored for long periods of time and are used as adhesives when necessary, but they have the drawback of requiring very high curing temperatures and long curing times for bonding. In order to overcome this drawback, a curing accelerator is used, but there is a problem in that the storage stability of the composition is significantly reduced depending on the combination of the curing agent and the accelerator. Moreover, depending on the type of curing agent and accelerator used, the excellent characteristics of polysulfide-modified epoxy resins may not be fully exhibited in many cases. Therefore, it is extremely difficult and important to find a combination of curing agent and accelerator that does not adversely affect the storage stability and takes advantage of the characteristics of polysulfide-modified epoxy resins. The inventors of the present invention conducted extensive research in view of this point, and found that a composition containing a polysulfide-modified epoxy resin, an amine-based latent curing agent as a curing agent, and a specific urea compound as a curing accelerator has good curability as well as It was discovered that it has good storage stability and excellent properties as an adhesive, especially peeling properties, leading to the present invention. That is, the object of the present invention is to obtain a sulfide-modified epoxy resin obtained by reacting a long-chain aliphatic polysulfide compound having a thiol group at the molecular end with an epoxy resin, an amine-based latent curing agent, and a compound of the general formula (1). ) (In the formula, R ₁ , R ₂ , R ₃ are hydrogen atoms, carbon atoms 1 to 4
represents either an alkyl group or a substituted or unsubstituted aromatic hydrocarbon residue, R ₁ , R ₂ ,
At least two of R ₃ are alkyl groups) or general formula (2) (wherein, X includes substituted or unsubstituted aromatic group 2
a urea compound represented by _a hydrogen atom or _an alkyl group having 1 _{to 4} carbon atoms; It is a liquid epoxy resin composition. Polysulfide compounds having a thiol group at the molecular end, which are raw materials for the polysulfide-modified epoxy resin, which is one of the essential components used in the present invention, include (1) formaldehyde-dichloromethylal, formaldehyde-β-dichlorodiethyl; Acetal, formaldehyde-chloromethyl-β-
Chlorethyl acetal, acetaldehyde
Dichloro-methylal, acetaldehyde-β
- Polysulfide compounds obtained by the reaction of dichlorinated acetals such as dichlorodiethyl acetal and polysulfide sodium compounds such as sodium tetrasulfide (2) 1,2-dichloroethane, 1,2-dichloropropane, Polysulfide compounds obtained by the reaction of dichlorinated paraffins such as 1,3-dichloropropane and polysulfide sodium compounds such as sodium tetrasulfide (3) 1,1'-dichlorodimethyl ether, 2,
Polysulfide compounds obtained by the reaction of dichlorinated ethers such as 2'-dichlorodiethyl ether and 1-chloromethyl-2-chloroethyl ether with polysulfide sodium compounds such as sodium tetrasulfide (4) Butadiene, Polysulfide compounds obtained by the reaction of diolefins such as isoprene with dimercaptan compounds such as ethylene dithioglycol and propylene dithioglycol (5) Polysulfide compounds obtained by oxidation of dimercaptan compounds (6) In this way Examples include polysulfide compounds obtained by a mixture of the obtained polysulfide compounds or by co-reaction, which have a thiol group at the molecular end and have a molecular weight in the range of 300 to 20,000, preferably 400 to 10,000. Epoxy resin, which is the other raw material for polysulfide-modified epoxy resin, is a polyepoxide having two or more epoxy groups per molecule,
Preferred examples include epoxy resins obtained from bisphenols such as bisphenol A and bisphenol F and epichlorohydrin, and epoxy resins obtained from hydrogenated bisphenols such as hydrogenated bisphenol A and epichlorohydrin. Other useful polyepoxides include (1) polyglycidyl ethers of novolac resins and similar polyphenols, (2) polyglycidyl ethers of polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, and glycerin; (3) Glycidyl esters of dicarboxylic acids such as phthalic acid and hydrogenated phthalic acid; (4) acrylic copolymers with epoxy groups such as glycidyl acrylate and glycidyl methacrylate; (5) epoxidized products of diolefin polymers such as polybutadiene. Examples include. Various amine-based latent curing agents are known as other essential components of the composition of the present invention.
Either of them can be used. Specifically, for example, 1-cyanoguanidine (dicyandiamide), 1,
Guanidine compounds such as 3-diphenylguanidine, p-tolylguanidine, guanylurea, benzoyldicyandiamide, phenylbiguanide, xylenylbiguanide, oxalic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, azelaic acid dihydrazide , phthalic acid dihydrazide, dimer acid dihydrazide, and other polyvalent carboxylic acid polyhydrazide compounds. The amount of the amine-based latent curing agent to be used is in the range of 0.3 to 1.5 equivalents, preferably 0.5 to 1.0 equivalents, based on all the epoxy groups contained in the composition of the present invention. The urea compound represented by the general formula (1) or (2), which is another essential component of the composition of the present invention, is specifically, for example, 3-phenyl-1,1-
Dimethylurea, 3-(4-methoxyphenyl)1,
1-Dimethylthylurea, 3-(4-chlorophenyl)
- Urea compounds corresponding to general formula (1) such as -1,1-dimethylurea, dimethylurea, trimethylurea,
1,1'-(4-methyl-m-phenylene)-bis(3,3-dimethylurea), 1,1'-(methylenedi-p-phenylene)-bis(3,3-dimethylurea)
Examples include urea compounds corresponding to general formula (2) such as. The amount of the urea compound used as a curing accelerator is in the range of 0.1 to 1.5 times, preferably 0.2 to 1.0 times the weight of the amine latent curing agent. The composition of the present invention has the above-mentioned three essential components as its main components, but in addition to these three components, the composition of the present invention may also contain epoxy resins that are not modified with polysulfide, modified by other means such as urethane modification, silicone modification, etc. Epoxy resins, various organic compounds known as reactive and non-reactive diluents, silica, alumina, talc, calcium carbonate asbestos, titanium oxide, carbon black,
Fillers or thixotropic agents such as glass beads, short glass fibers, metal powder, conductive fillers such as conductive carbon black, carbon fiber, gold powder, silver powder, nickel powder, stainless fiber, trilead tetroxide, aluminum polyphosphate It may contain rust-preventive pigments such as, thermoplastic resins, thermosetting resins, coloring dyes and pigments, solvents, etc. The composition of the present invention comprises a polysulfide-modified epoxy resin, an amine-based latent curing agent, a urea compound represented by the general formula (1) or (2), and optionally an epoxy resin that is not modified with polysulfide.
It is manufactured by mixing, kneading, and uniformly dispersing diluents, thixotropic agents, fillers, pigments, etc. in accordance with conventional methods. The composition of the present invention is characterized by not only excellent curability but also good storage stability. Furthermore, when used as an adhesive, it not only exhibits semi-permanently high peel strength not found in other epoxy resin adhesives, but also exhibits shear strength, heat resistance, oil adhesion, water resistance, and chemical resistance. Shows excellent properties in terms of sex. Therefore, it is an extremely suitable material as an adhesive sealant between metal materials in fields where strength as a structural material is required. The present invention will be described in more detail with reference to Examples below, but the present invention does not exceed the gist thereof.
The present invention is not limited to the following examples. In addition,
"Parts" and "%" in the examples are based on weight unless otherwise specified. [Production of sulfide-modified epoxy resin] Example 1 Diglycidyl ether type epoxy resin of bisphenol A (epoxy equivalent: 185, viscosity: 13,500 cps/
25℃, Dainippon Shikizai Kogyo Priepo PE-10) 75
Thiol group-terminated polysulfide synthesized from formaldehyde-β-dichlorodiethyl acetal and sodium tetrasulfide according to a conventional method HS- _CH2 - _CH2 -O-CH2 _- O- _CH2 - _CH2
(-S-S-CH ₂ -CH ₂ -O-CH ₂ -O-CH ₂ -
CH ₂ -) 25 parts of ₅ SH (average molecular weight 1000, viscosity 1100 cps/25°C, SH content 6.5%) and 2,4.6-tri- as a catalyst.
When 0.05 part of (dimethylaminomethyl)-phenol was mixed in a flask purged with nitrogen, the temperature was raised to 90℃ and the reaction was carried out for 3 hours.The viscosity was 21,200 cps/25℃.
A yellowish brown viscous product was obtained. Example 2 50 parts of diglycidyl ether type epoxy resin of bisphenol A used in Example 1 (Priepo-PE-10 manufactured by Dainippon Shikizai Kogyo), 5 parts of butyl glycidyl ether, diglycidyl ether type epoxy resin of polypropylene glycol (epoxy equivalent weight 320,
Viscosity 80cps/25℃, Dow Chemical DER-732)
5 parts, 40 parts of thiol group-terminated polysulfide (average molecular weight 1000, viscosity 1200 cps/25°C, Thiokol LP-3 manufactured by Toray Thiokol) and 2,4,6-
Tri-(dimethylaminomethyl)-phenol 0.05
Mix the two parts in a nitrogen-filled flask and heat at 80℃ for 4 hours.
After reacting for an hour, a yellow viscous product with a viscosity of 135000 cps/25°C was obtained. Example 3 45 parts of the diglycidyl ether type epoxy resin of bisphenol A used in Example 1 (Priepo-PE-10, manufactured by Dainippon Shikizai Kogyo), and the diglycidyl ether type epoxy resin of polypropylene glycol used in Example 2 (Dow Co., Ltd.). Chemical DER-732), 10 parts of phenyl glycidyl ether, 40 parts of the thiol group-terminated polysulfide used in Example 2 (Thiokol LP-3, manufactured by Toray Thiokol), and 2,4,6
-tri-(dimethylaminomethyl)-phenol
Mix 0.05 part in a flask purged with nitrogen,
After reacting for 3 hours at °C, a yellow-brown viscous product with a viscosity of 15000 cps/25 °C was obtained. [Examples and Comparative Examples] The sulfide-modified epoxy resins obtained in Examples 1 to 3 above and the types and amounts of curing agents, curing accelerators, diluents, and fillers shown in Table 1 were blended, and three-roll etc. Epoxy resin compositions Examples A to F and Comparative Examples G to K were manufactured by uniformly dispersing the compositions using a kneader. Adhesion tests and storage stability tests were conducted using these epoxy resin compositions A to K. During adhesion, the epoxy resin composition was cured by heating at 120°C for 40 minutes. The test method is as follows. (1) Single lap tensile shear strength Measured according to JIS-K6850. The adherend is a cold rolled steel plate specified in JIS-G3141.
SPCC-SB was used. Test atmosphere 23±1°C 65±5%RH Measurement conditions Tensile loading rate 5mm/min (2) T-peel strength Measured in accordance with JIS-K6854. SPCC-SB specified in JIS-G3141 was used as the adherend. Test atmosphere 23±1℃ 65±5%RH Measurement conditions Tensile loading rate 50mm/min (3) Oil surface adhesion Evaluated according to JIS-K6830. P-1400 manufactured by Nippon Oil Co., Ltd. was used as the rust preventive oil. Test atmosphere 23±1℃, 65±5%RH (4) Heat resistance deterioration (flexibility aging acceleration test) An epoxy resin composition was applied to a 200μ thick SPCC-SB steel plate specified in JIS-G3141. Apply 120
After curing at ℃ for 40 minutes, heat treatment was further performed at 200℃ for 1 hour, and a bending adhesion test was performed before and after the heat treatment.
This was done in accordance with JIS-K5400. Note that the test was performed after making a cut in the bent portion with a knife. Test atmosphere 23±1°C, 65±5% RH (5) Storage stability After storing the epoxy resin composition at 50°C for one week, the test described in item (1) was conducted to check for changes in appearance.

[Table] In Table 1, unmodified epoxy (a) is Dainippon Shikizai Kogyo's Priepo-PE-10 (epoxy equivalent: 185, viscosity: 13,500 cps/25
℃) Urethane-modified epoxy (b) is EPOTHERM SU-500R manufactured by Mitsubishi Chemical Industries (epoxy equivalent: 245, viscosity:
34500cps/25℃) Diluent (c) is DER-732 manufactured by Dow Chemical Diluent (d) is Epicoat 871 manufactured by Yukasil Epoxy Diluent (e) is phenyl glycidyl ether Conductive carbon black (f) is Lion Oil The anti-rust pigment (g) is K-White manufactured by Teikoku Kako Co., Ltd. The test results are shown in Table-2. From these results,
Compared to the example composition using polysulfide-modified epoxy resin, the comparative example composition using unmodified epoxy was inferior in peel strength, oil adhesion, flexibility, and storage stability, and the composition using urethane-modified epoxy was inferior. It can be seen that the flexibility of the comparative example composition is also not sufficient, and a decrease in flexibility is expected to occur due to changes over time. Furthermore, it can be seen that the curability of the comparative example composition which does not use a urea compound is completely poor.

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Claims (1)

[Claims] 1. A sulfide-modified epoxy resin obtained by reacting a long-chain aliphatic polysulfide compound having a thiol group at the molecular end with an epoxy resin, an amine-based latent curing agent, and general formula (1) (In the formula, R ₁ , R ₂ , R ₃ are hydrogen atoms, carbon atoms 1 to 4
represents either an alkyl group or a substituted or unsubstituted aromatic hydrocarbon residue, R ₁ , R ₂ ,
At least two of R ₃ are alkyl groups)
or general formula (2) (wherein, X is 2 containing a substituted or unsubstituted aromatic ring)
represents a valent hydrocarbon residue, and R ₄ , R ₅ , R ₆ and R ₇ are hydrogen atoms or alkyl groups having 1 to 4 carbon atoms. ) A one-component epoxy resin composition characterized by containing a urea compound represented by: