JP2019137798A - Epoxy resin composition - Google Patents

Abstract

To provide an epoxy resin composition having excellent adhesiveness to a steel sheet, with its temperature dependence being low.SOLUTION: An epoxy resin composition has (A) an epoxy resin containing polytetramethylene glycol diglycidyl ether and (B) a latent curing agent as the essential components, and has a post-curing glass transition temperature of 55-120°C.SELECTED DRAWING: None

Description

  The present invention relates to an epoxy resin composition containing polytetramethylene glycol diglycidyl ether.

  Adhesives for transport machinery are mainly used in manufacturing processes for aircraft, railway vehicles, automobiles, ships, and the like. One-pack type epoxy adhesives are widely used in these applications because of their high adhesive strength to steel plates. However, since the epoxy resin is hard and brittle, stress is not dispersed when a load is applied to the adhesive, and the epoxy resin tends to concentrate on one point. Therefore, there is a problem that peeling or destruction is likely to occur at the bonded portion.

  As a method for improving the adhesiveness of the epoxy resin composition, a method of blending a glycidyl ether having a polypropylene glycol structure is known. For example, Patent Document 1 discloses a method of blending polypropylene glycol diglycidyl ether with diglycidyl ether of a bisphenol A-alkylene oxide adduct, and Patent Document 2 discloses a flaky adhesive formed of a rubber-modified epoxy resin and polypropylene glycol diglycidyl ether. A method for dispersing mica powder has been proposed. Patent Document 3 proposes a method of blending a urethane-modified epoxy resin with a polypropylene glycol-containing epoxy resin.

  In order to be used as an adhesive for the above-mentioned transportation machinery, it is a matter of course that excellent adhesion is required, but during a manufacturing process or the life of a vehicle, a very wide range of adhesion is required. Sex is required. These temperatures may be exposed to temperatures as high as 80 ° C or as low as -40 ° C. However, existing adhesives for transport machinery have low mechanical strength when used at high temperatures and low flexibility when used at low temperatures. Therefore, it cannot be suitably used for applications that are used in a wide temperature range from a low temperature to a high temperature, such as an adhesive for transport machinery.

JP 2007-284467 A Japanese Unexamined Patent Publication No. 63-280785 Japanese Patent No. 5086774

  Therefore, this invention is providing the epoxy resin composition which is excellent in the adhesiveness with respect to a steel plate, and its temperature dependency is low.

  In order to solve the above-mentioned problems, the present inventors made a cured product of an epoxy resin composition using a plurality of liquid epoxy compounds, and evaluated adhesiveness at various temperatures. As a result, (A) an epoxy resin containing polytetramethylene glycol diglycidyl ether, and (B) an epoxy resin composition having a latent curing agent as an essential component and a glass transition temperature after curing of 55 to 120 ° C. By using it, it came to solve the said subject.

  According to the present invention, it is possible to provide an epoxy resin composition that is excellent in adhesion to a steel plate and has low temperature dependency. The epoxy resin composition of the present invention can be widely used regardless of the material such as a metal material or a plastic material, but is suitable for adhesion of iron parts used in, for example, automobiles and machine products. In particular, it is useful as an adhesive for weld bonds and hemming used in the assembly process of automobiles.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Modes for carrying out the present invention will be described in detail below, but the scope of the present invention is not limited to these embodiments, and modifications and the like are added without departing from the spirit of the present invention. Also belong to the present invention. The notation “˜” representing a range includes an upper limit and a lower limit.

  The polytetramethylene glycol diglycidyl ether in the component (A) of the epoxy resin composition of the present invention is obtained by reacting polytetramethylene glycol and epichlorohydrin, and can be produced by using a known production method. Although not particularly limited, the epoxy equivalent calculated by titration with perchloric acid in the presence of acetic acid and cetyltrimethylammonium bromide according to JIS K7236 is preferably 200 to 1500, and the release of the epoxy resin composition In consideration of the strength, it is more preferably in the range of 350 to 550. For example, SR-PTMG (manufactured by Sakamoto Pharmaceutical Co., Ltd.) is preferable.

  As the component (A) in the present invention, bisphenol type epoxy resin, urethane modified epoxy resin, rubber modified epoxy resin, novolac type epoxy resin, polyfunctional phenol resin, resorcinol type epoxy resin, glycidyl ester type epoxy resin, cyclic aliphatic epoxy resin Hydantoin type epoxy resins, glycidyl amine type epoxy resins, monofunctional or polyfunctional aliphatic epoxy resins, and the like can be used. A bisphenol type epoxy resin is particularly preferable.

  Specific examples of the bisphenol type epoxy resin include bisphenol A type epoxy resin, diglycidyl ether of bisphenol A alkylene oxide adduct, bisphenol F type epoxy resin, diglycidyl ether of bisphenol F alkylene oxide adduct, and bisphenol AD type epoxy. Resin, bisphenol S type epoxy resin, tetramethyl bisphenol A type epoxy resin, tetramethyl bisphenol F type epoxy resin, etc. Among them, bisphenol A type epoxy resin and bisphenol F type epoxy resin are in terms of handleability. An epoxy resin that is liquid at 25 ° C. is particularly preferable.

  Specific examples of the monofunctional or polyfunctional aliphatic epoxy resin include n-butyl glycidyl ether, higher alcohol glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, p-sec. -Butylphenyl glycidyl ether, t-butylphenyl glycidyl ether, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, butanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycidyl Examples include ether, 1,6-hexanediol diglycidyl ether, and trimethylolpropane polyglycidyl ether. These may be used singly or in combination of two or more.

  The blending ratio of polytetramethylene glycol diglycidyl ether in the component (A) is preferably 25 to 45 parts by weight, and more preferably 30 to 40 parts by weight in view of the physical properties of the cured product of the epoxy resin composition. preferable.

  Any of the latent curing agents may be used as the curing agent, and a curing accelerator may be used in combination as necessary.

  As the latent curing agent in the present invention, a normal curing agent that exhibits a curing action by heating and generally activated in a temperature range of 80 to 250 ° C. can be used. Specific examples of latent curing agents include dicyandiamide, 4,4′-diaminodiphenylsulfone, imidazole derivatives such as 2-n-heptadecylimidazole, isophthalic acid dihydrazide, N, N-dialkylurea derivatives, N, N-di Examples thereof include alkylthiourea derivatives and melamine derivatives.

  The blending ratio of the latent curing agent is preferably 6 to 12 parts by weight with respect to 100 parts by weight of the (A) component epoxy resin. When the blending ratio of the latent curing agent is 6 to 12 parts by weight, the curability is excellent and the adhesive strength is increased.

  The present invention is not limited to the epoxy resin of component (A) and the latent curing agent of component (B), and is within the range that does not impair the effects of the invention, colorant, antioxidant, leveling agent, surfactant Agents, ultraviolet absorbers, silane coupling agents, inorganic fillers, resin particles, wettability improvers, antifoaming agents, light stabilizers, heat stabilizers, additives such as calcium carbonate, talc, silica, barium sulfate, etc. An inorganic filler or the like can be used in combination.

  The glass transition temperature of the hardened | cured material which hardened | cured the epoxy resin composition of this invention is 55-120 degreeC, and 70-95 degreeC is more preferable. When the glass transition temperature is in the range of 55 to 120 ° C., a cured product having excellent adhesiveness and low temperature dependency can be obtained. The glass transition temperature referred to here is a cured product cured at 150 ° C. for 1 hour, and a temperature rise rate of 5 ° C./min. With a dynamic viscoelasticity measuring device according to JIS K7244. Refers to the temperature when measured at a frequency of 1 Hz.

  Specific examples are shown below, but the present invention is not limited to the following examples. The units in the tables in the examples were “parts by weight” unless otherwise specified.

Example 1
25 parts by weight of polytetramethylene glycol diglycidyl ether, 75 parts by weight of bisphenol A type epoxy resin as a bisphenol type epoxy resin, 6 parts by weight of dicyandiamide as a latent curing agent, 16 parts by weight of calcium carbonate as an inorganic filler, hydrophilic as a thixotropic agent 1 part by weight of fumed silica and 1 part by weight of 1-benzyl-2-methylimidazole as a curing accelerator were mixed until uniform to obtain an epoxy resin composition.

(Example 2) to (Example 4)
Except having changed the compounding quantity of the epoxy resin used for Example 1, operation similar to Example 1 was performed and the epoxy resin composition was obtained.

(Comparative Examples 1-3)
Except having changed the compounding quantity using polypropylene glycol diglycidyl ether instead of polytetramethylene glycol diglycidyl ether, operation similar to Examples 1-4 was performed, and the epoxy resin composition was obtained.

<Glass transition temperature>
The epoxy resin compositions described in Examples 1 to 4 and Comparative Examples 1 to 3 were defoamed under reduced pressure, then poured into a mold and thermally cured at 150 ° C. for 1 hour to obtain a cured product. Thereafter, the glass transition temperature was measured according to JIS K7244. As a measuring instrument, a dynamic viscoelasticity measuring device DMS6100 (manufactured by Hitachi High-Tech Science Co., Ltd.) was used. The temperature rising rate was 5 ° C./min. The frequency was 1 Hz.

<T-type peel strength>
The adherend of the test piece was degreased with acetone using a cold rolled steel plate SPCC-SB (300 × 25 × 0.3 mm). The epoxy resin compositions described in Examples 1 to 4 and Comparative Examples 1 to 3 were applied to adherends so as to have a thickness of 100 μm, and bonded together, and then thermally cured at 170 ° C. for 40 minutes. Got. Thereafter, T-type peel strength was measured according to JIS K6854. Autograph AG-IS 20 kN desktop type (manufactured by Shimadzu Corporation) was used in the test at 23 ° C., and Technograph TGI-50 kN (manufactured by Minebea Co., Ltd.) was used in the test at −40 to 80 ° C. A T-type peel strength of 40 N / 25 mm or more and less than 80 N / 25 mm was judged as “good”, and a T-type peel strength of 80 N / 25 mm or more was judged as “excellent”.

<Tensile shear strength>
The adherend of the test piece was degreased with acetone using a cold rolled steel plate SPCC-SB (100 × 25 × 1.6 mm). The epoxy resin compositions described in Examples 1 to 4 and Comparative Examples 1 to 3 were applied to adherends so as to have a thickness of 100 μm, and bonded together, and then thermally cured at 170 ° C. for 40 minutes. Got. Thereafter, the tensile shear strength was measured according to JIS K6850. Autograph AG-IS 20 kN desktop type (manufactured by Shimadzu Corporation) was used in the test at 23 ° C., and Technograph TGI-50 kN (manufactured by Minebea Co., Ltd.) was used in the test at −40 to 80 ° C. Those having a tensile shear strength of 17 MPa or more and less than 20 MPa were judged as “good”, and those showing a value of 20 MPa or more were judged as “excellent”.

  Table 1 shows the T-type peel strength and tensile shear strength at 23 ° C. of the epoxy resin compositions obtained in Examples 1 to 4 and Comparative Examples 1 to 3.

  As shown in Table 1, Examples 1 to 4 using the epoxy resin composition according to the present invention showed good values for both T-type peel strength and tensile shear strength, and were found to be excellent in adhesiveness. It was. In particular, Examples 2 and 3 are superior to Comparative Examples 1 and 2 in which the same amount of polypropylene glycol diglycidyl ether is blended in place of polytetramethylene glycol diglycidyl ether and Comparative Example 3 in which the blending amount is increased. Had good adhesion.

(Example 5), (Comparative Example 4)
Next, from Examples and Comparative Examples, adhesion at −40 to 80 ° C. was performed using the epoxy resin compositions of Example 3 and Comparative Example 3 that had a good balance between T-type peel strength and tensile shear strength. The properties were evaluated by T-type peel strength and tensile shear strength. The results are shown in Table 2.

  As shown in Table 2, Example 5 using the cured product of the epoxy resin composition of the present invention showed higher T-type peel strength and tensile shear strength in a wider temperature range than Comparative Example 4, and the temperature It was shown that the dependency was low. As described above, the epoxy resin composition containing (A) an epoxy resin containing polytetramethylene glycol diglycidyl ether and (B) a latent curing agent as an essential component and having a glass transition temperature after curing of 55 to 120 ° C. It was shown that the adhesion was excellent and its temperature dependency was low.

Claims (4)

(A) Component; Epoxy Resin (B) Component; Latent Curing Agent An epoxy resin composition containing (A) and (B) as essential components, wherein (A) component is polytetramethylene glycol diglycidyl ether An epoxy resin composition comprising a cured product obtained by curing the epoxy resin composition having a glass transition temperature of 55 to 120 ° C.   The epoxy resin composition according to claim 1, wherein the component (A) contains a bisphenol type epoxy resin.   The epoxy resin composition according to claim 1 or 2, wherein the latent curing agent of component (B) is one or more containing dicyandiamide.   The adhesive composition for the machines for transport containing the epoxy resin composition in any one of Claims 1-3.