JP4588817B2 - One-pack type epoxy resin adhesive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a novel one-pack type epoxy resin adhesive, and more specifically, it is suitably used for adhesion between the iron core of an ignition coil and a case that are particularly required to have thermal shock resistance, and when thermally cured. The present invention relates to a one-pack type epoxy resin adhesive that provides a cured product with excellent thermal shock resistance.
[0002]
[Prior art]
Conventionally, as an adhesive between an iron core and a case such as an ignition coil that requires thermal shock resistance, for example, a one-pack type epoxy resin adhesive containing asbestos to improve thermal shock resistance, rubber and epoxy A one-pack type epoxy resin adhesive in which a rubber-modified epoxy resin reacted with a resin is used as a main component and a needle-like inorganic filler is blended therein is known. However, asbestos and needle-like inorganic fillers are in a direction that their use is restricted due to environmental pollution, and a one-pack type epoxy resin adhesive containing a rubber-modified epoxy resin obtained by reacting rubber and an epoxy resin. Although the toughness of the cured product obtained by thermosetting it has been improved, the glass transition point is lowered, and there is a drawback that it cannot be used for applications requiring thermal shock resistance.
[0003]
[Problems to be solved by the invention]
Under such circumstances, the present invention provides a cured product excellent in thermal shock resistance and other physical properties suitable for use in, for example, adhesion between an iron core of an ignition coil and a case that are required to have thermal shock resistance. The purpose of the present invention is to provide a one-pack type epoxy resin-based adhesive.
[0004]
[Means for Solving the Problems]
As a result of intensive research to develop a one-pack type epoxy resin adhesive that gives a cured product exhibiting excellent thermal shock resistance even without the incorporation of asbestos or acicular inorganic filler, the present inventors have conducted chelate formation. The above-mentioned object is achieved by blending a liquid urethane-modified epoxy resin having a function, crosslinked rubber fine particles having a specific average particle size, a liquid bisphenol type epoxy resin, a latent curing agent, and a curing accelerator in specific ratios, respectively. Based on this finding, the present invention has been completed.
[0005]
That is, the present invention includes (A) 20 to 70% by weight of a liquid urethane-modified epoxy resin having chelate-forming ability, and (B) 6 to 20% by weight of crosslinked rubber fine particles having an average particle size of 0.05 to 0.5 μm, (C) 2 to 20 parts by weight of a latent curing agent and (E) 0.1 to 20 parts by weight of a curing accelerator with respect to 100 parts by weight of a resin component consisting of 10 to 65% by weight of a liquid bisphenol F type epoxy resin. The present invention provides a one-pack type epoxy resin adhesive obtained by blending parts.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the one-pack type epoxy resin adhesive of the present invention, it is necessary to use a liquid urethane-modified epoxy resin having chelate forming ability as the component (A). This includes diisocyanate compounds such as tolylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dimethylhexamethylene diisocyanate, bisphenol A type epoxy resin having at least one hydroxyl group in one molecule, bisphenol F type epoxy resin, etc. It is produced by reacting a bisphenol type epoxy resin with a polyol having a polyaminocarboxylic acid group such as ethylenediaminetetraacetic acid, a condensed phosphoric acid skeleton or the like.
This liquid urethane-modified epoxy resin having chelate-forming ability may be used alone or in combination of two or more.
[0007]
Next, in the adhesive of the present invention, it is necessary to use crosslinked rubber fine particles as the component (B). For example, acrylic rubber, butadiene rubber, silicone rubber, ethylene-propylene rubber, acrylonitrile- It consists of a crosslinked rubber such as butadiene rubber. These may be used singly or as a mixture of two or more, but are composed of a cross-linked product of acrylonitrile-butadiene rubber from the viewpoint of dispersibility in epoxy resin and heat cycle resistance of a cured product. Fine particles are preferred.
[0008]
The average particle size of the crosslinked rubber fine particles needs to be in the range of 0.05 to 0.5 μm. If the average particle size is less than 0.05 μm, the viscosity of the adhesive is high and handling properties are poor, and if it exceeds 0.5 μm, it is difficult to obtain a cured product having sufficient heat cycle resistance. Considering the viscosity of the adhesive and the heat cycle resistance of the cured product, the preferable range of the average particle diameter is 0.05 to 0.2 μm.
[0009]
In the adhesive of the present invention, it is necessary to use a liquid bisphenol type epoxy resin as the component (C). This liquid bisphenol-type epoxy resin is liquid at an average room temperature, that is, 25 ° C., and this can be arbitrarily selected from known bisphenol-type epoxy resins that are liquid at room temperature. However, from the viewpoint of workability, for example, dispenser application workability, a low viscosity liquid bisphenol F type epoxy resin having an epoxy equivalent in the range of 120 to 240 is particularly suitable.
In the present invention, this liquid bisphenol type epoxy resin may be used alone or in combination of two or more.
[0010]
Regarding the blending ratio of the component (A), the component (B) and the component (C) in the adhesive of the present invention, the blending amount of the liquid urethane-modified epoxy resin of the component (A) is the resin component amount, that is, the component (A). Based on the total amount of component (B) and component (C), it is necessary to be in the range of 20 to 70% by weight. If this amount is less than 20% by weight, a cured product having sufficient physical properties such as sufficient elongation, low elastic modulus and deformation followability cannot be obtained, and if it exceeds 70% by weight, the viscosity of the adhesive is increased and handling properties are improved. It becomes worse and the reactivity is lowered. Considering the elongation percentage of the cured product, the viscosity and reactivity of the adhesive, the preferable blending amount of the component (A) is in the range of 30 to 60% by weight.
[0011]
Moreover, the compounding quantity of the crosslinked rubber fine particle of (B) component needs to exist in the range of 6-20 weight% based on the total amount of (A) component, (B) component, and (C) component. . If this amount is less than 6% by weight, a cured product having sufficient heat cycle resistance cannot be obtained, and if it exceeds 20% by weight, the viscosity of the adhesive becomes too high, making it difficult to disperse in an epoxy resin. Considering the heat cycle resistance of the cured product and the dispersibility in the epoxy resin, the preferable blending amount of the component (B) is in the range of 6 to 15% by weight.
[0012]
On the other hand, the blending amount of the liquid bisphenol-type epoxy resin of component (C) needs to be in the range of 10 to 75% by weight based on the total amount of component (A), component (B) and component (C). It is. If the amount is less than 10% by weight, the viscosity of the adhesive becomes high, the handling property is deteriorated and the reactivity is lowered, and if it exceeds 75% by weight, desired properties such as low elastic modulus and heat cycle resistance are obtained. A cured product cannot be obtained. Considering the viscosity and reactivity of the adhesive, the elastic modulus of the cured product, the heat cycle resistance, etc., the preferred blending amount of this component (C) is in the range of 30 to 65% by weight.
[0013]
In the adhesive of the present invention, the crosslinked rubber fine particles of the component (B) and the liquid bisphenol type epoxy resin of the component (C) are in a state where the component (B) is dispersed in the component (C) to form a sea-island structure. It is preferable to be included in the adhesive. Thereby, even if toughness improves, the heat resistant hardened | cured material in which a glass transition point does not fall is obtained.
[0014]
In the adhesive of the present invention, examples of the latent curing agent used as component (D) include dicyandiamide, organic acid hydrazide compounds, polyamine salt compounds, amine adduct compounds, and the like. Alternatively, two or more kinds may be used in combination, but dicyandiamide is preferred from the viewpoint of the adhesive strength of the cured product and the pot life of the adhesive.
[0015]
The blending amount of the latent curing agent of the component (D) is 2 to 20 weights with respect to the resin component amount, that is, 100 parts by weight of the total amount of the component (A), the component (B) and the component (C). It is necessary to be in the range of parts. If this amount is less than 2 parts by weight, the curing rate of the adhesive is slow and the adhesive strength of the cured product is insufficient, and if it exceeds 20 parts by weight, the glass transition temperature of the cured product is remarkably lowered and the heat resistance is poor. Become. In consideration of the curing speed, the adhesive strength of the cured product, the heat resistance, and the like, the preferable blending amount of the component (D) is in the range of 4 to 15 parts by weight.
[0016]
In the adhesive of the present invention, examples of the curing accelerator used as the component (E) include urea compounds, phosphine compounds, imidazole compounds, and the like. These may be used alone or in combination of two or more. Although they may be used in combination, methylenediphenylbisdimethylurea and toluenebisdimethylurea are preferred, and methylenediphenylbisdimethylurea is particularly preferred from the standpoint that the glass transition temperature does not decrease and the pot life is long. .
[0017]
The blending amount of this (E) component curing accelerator is 0.1-20 with respect to the resin component amount, that is, 100 parts by weight of the total amount of the component (A), the component (B), and the component (C). It must be in the range of parts by weight. If this amount is less than 0.1 parts by weight, the curing rate of the adhesive is slow, and if it exceeds 20 parts by weight, the glass transition temperature of the cured product is lowered. Considering the curing speed and the heat resistance of the cured product, the preferable blending amount of the component (E) is in the range of 0.5 to 20 parts by weight.
[0018]
It is preferable that the one-pack type epoxy resin adhesive of the present invention is blended with an inorganic filler having an effect of improving heat resistance, curing strain resistance and the like as desired. Examples of this inorganic filler include calcium carbonate, silica, alumina, aluminum hydroxide, magnesium oxide, talc, mica, clay and the like. These may be used alone or in combination of two or more. However, calcium carbonate is preferable because it can be easily dispersed in an adhesive. The blending amount of the inorganic filler is usually 200 parts by weight or less, preferably 100 parts by weight or less with respect to 100 parts by weight of the total amount of the components (A), (B) and (C). .
Considering the viscosity of the adhesive and clogging to the dispenser nozzle, it is usually preferable to use those having an average particle size of 0.1 to 100 μm, preferably an average particle size of 0.5 to 10 μm.
[0019]
The one-pack type epoxy resin adhesive of the present invention preferably contains a thixotropic agent having an effect of improving workability such as dripping prevention. As the thixotropic agent, ultrafine silica, ultrafine alumina, ultrafine calcium carbonate or the like can be used alone or in combination. The blending amount of the thixotropic agent is usually 1 to 50 parts by weight, preferably 2 to 30 parts by weight with respect to 100 parts by weight of the total amount of the component (A), the component (B) and the component (C). Selected by range.
Furthermore, in the one-pack type epoxy resin adhesive of the present invention, various conventionally used additives such as reactive diluents, flame retardants, and the like are used as long as the object of the present invention is not impaired. An antifoaming agent, a surfactant, a colorant, and the like can be blended.
[0020]
There is no restriction | limiting in particular as a preparation method of the one-pack type epoxy resin-type adhesive of this invention, For example, (A)-(E) component which is an essential component, the inorganic filler which is a desired component, thixotropic agent, various addition It can be prepared by mixing the agent homogeneously. However, from the viewpoint of workability and thermal shock resistance of the cured product, the (B) component is dispersed in the (C) component in advance as described above, and the sea-island structure. It is advantageous to mix with other ingredients in the state of
[0021]
【The invention's effect】
The one-pack type epoxy resin adhesive of the present invention is excellent in heat cycle resistance and heat resistance when it is heat-cured, and a cured product having a glass transition temperature of 125 ° C. or higher is obtained. As an adhesive for obtaining a cured product having good adhesion between a steel plate, for example, a metal such as SPCC or silicon steel plate, and a plastic such as polybutylene terephthalate and having excellent thermal shock resistance, vibration resistance during heating is required. It is suitably used for bonding the iron core of the ignition coil and the case.
[0022]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
The physical properties of the adhesive and its cured product were measured by the following methods.
[0023]
(1) Viscosity Using an EHD viscometer, the viscosity was measured at 25 ° C. and a rotation speed of 2.5 rpm.
(2) Gelation time A gel plate based on JIS C 2104 is kept at 150 ° C., a 0.4 ml sample is placed on the plate, and after the placement, the time until the yarn is not broken by stirring with a stirring rod, That is, the time (s) until gelation was measured.
(3) Flexural strength, flexural modulus Based on JIS K 6911, about 5 test pieces obtained by curing a sample having a width of 10 mm and a height of 4 mm at 100 ° C. for 1 hour and further at 120 ° C. for 3 hours, a temperature of 25 The average value of the measured values obtained by bending test under the conditions of ° C., crosshead moving speed 3 mm / min, span 64 mm is shown.
(4) About a test piece obtained by curing a glass transition temperature sample (15 mm × 5 mm × 5 mm) at 100 ° C. for 1 hour and further at 120 ° C. for 3 hours, using a thermomechanical analyzer manufactured by Mac Science Co., Ltd. / Min, measured under conditions of a load of 10 g, the inflection point was determined, and this was taken as the glass transition temperature.
(5) Heat cycle test An iron spring washer with a diameter of 20 mm is put in a petri dish with a diameter of 50 mm, and a sample is put so as to incorporate the washer, and is thermoset at 100 ° C. for 1 hour and further at 120 ° C. for 3 hours. After leaving at room temperature, the cured product in the petri dish was taken out to prepare a test piece.
For this test piece, one cycle of holding at -30 ° C. for 1 hour and then holding at 120 ° C. for 1 hour is repeated. X.
(6) Shear bond strength Based on JIS K 6850, after polishing SPCC-SD steel plate of 100mm x 25mm x 1.6mm with # 150 abrasive cloth, it becomes 12.5mm single overlap with the degreased one Apply, heat cure at 120 ° C for 3 hours, let stand at room temperature, measure shear bond strength in 25 ° C atmosphere with crosshead moving speed of 5mm / min, and measure 5 samples The average value was shown.
(7) T peel adhesion strength Based on JIS K 6854, SPCC-SD steel plate (150 mm x 25 mm x 0.5 mm) degreased was used as the adherend, and the sample was applied and cured at 120 ° C for 3 hours. A test piece was created.
The five test pieces were tested under the conditions of a temperature of 25 ° C. and a crosshead moving speed of 50 mm / min, the peel adhesion strength was measured, and the average value of the obtained measured values was shown.
[0024]
The specific contents of each component used are shown below.
(1) Liquid urethane-modified epoxy resin having chelating ability, manufactured by Asahi Denka Kogyo Co., Ltd., trade name “Adeka Resin EPU-78-11”, epoxy equivalent 230
(2) Liquid urethane-modified epoxy resin (does not have chelate-forming ability)
Asahi Denka Kogyo Co., Ltd., trade name “ADEKA RESIN EPU-6”, epoxy equivalent 235
(3) Liquid acrylonitrile-butadiene copolymer rubber modified epoxy resin (does not have chelating ability)
Asahi Denka Kogyo Co., Ltd., trade name “ADEKA RESIN EPR-1508”, epoxy equivalent 290
(4) Crosslinked NBR fine particles Crosslinked acrylonitrile-butadiene copolymer rubber fine particles, manufactured by JSR Corporation, trade name “FX-501”, average particle diameter of primary particles 0.07 μm
(5) Bisphenol F type epoxy resin oiled shell epoxy, product name “Epicoat 807”, epoxy equivalent 167
(6) Product name “Epicure DICY15”, average particle diameter of 7 to 10 μm, manufactured by Dicyandiamide oiled shell epoxy
(7) Methylene diphenyl bismethyl urea ACI Japan Co., Ltd., trade name “Omicure 52”
(8) Product name “Softon 1200”, manufactured by Calcium Carbonate Bihoku Flour Industry Co., Ltd., average particle size 1.80 μm
[0025]
Example 1, Comparative Examples 1-8
A one-pack type epoxy resin adhesive having the composition shown in Table 1 was prepared and its performance was evaluated. The results are shown in Table 1.
[0026]
[Table 1]

Claims (4)

(A) 20 to 70% by weight of liquid urethane-modified epoxy resin having chelate-forming ability, (B) 6 to 20% by weight of crosslinked rubber fine particles having an average particle diameter of 0.05 to 0.5 μm, and (C) liquid bisphenol F (D) 2 to 20 parts by weight of a latent curing agent and (E) 0.1 to 20 parts by weight of a curing accelerator are blended with 100 parts by weight of a resin component consisting of 10 to 65 % by weight of a type epoxy resin. One-pack type epoxy resin adhesive.  The one-pack type epoxy resin adhesive according to claim 1, wherein the crosslinked rubber fine particles of component (B) are fine particles comprising a crosslinked product of acrylonitrile-butadiene copolymer rubber.  The one-component epoxy resin adhesive according to claim 1 or 2, wherein the curing accelerator of component (E) is at least one selected from toluene bisdimethylurea and methylenediphenylbisdimethylurea. The crosslinked rubber fine particles of component (B) and the liquid bisphenol type epoxy resin of component (C) are contained in a state where the component (B) is dispersed in component (C) to form a sea-island structure. , 2 or 3 one-component epoxy resin adhesive.