JPH04325590A - Epoxy resin adhesive composition - Google Patents

Abstract

PURPOSE:To provide an epoxy resin adhesive compsn. having pregelling function, good temporary adhesiveness and excellent heat-resistant and water-resistant shear adhesive force after heat-curing. CONSTITUTION:The title compsn. is obtd. by compounding an epoxy resin which is liquid at ordinary temp., a curing agent for heat-curing and a powdery atom. thermoplastic resin with a glass transition temp. of 120 deg.C or higher and a mean particle size of 200mum or smaller at a specified ratio.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an epoxy resin adhesive composition, and more specifically, it exhibits a temporary adhesion function by causing pre-gelation when heated for a short time, and is then heated and cured to provide excellent adhesive properties. The present invention provides an epoxy resin adhesive composition that exhibits adhesive properties such as strength, heat-resistant adhesive strength, and water-resistant adhesive strength.

0002

[Prior Art] Conventionally, as a thermosetting adhesive that can be pre-gelled and then thermosetted for temporary adhesion, for example, a polyvinyl chloride plastisol using an epoxy resin as a base polymer is disclosed in West German Patent Publication No. 2002880. Disclosed is an adhesive to which is added. Also, JP-A-56-
No. 82865, Japanese Patent Application Laid-open No. 62-252491,
Japanese Patent Publication No. 2-48192 and Japanese Patent Publication No. 2-48193 disclose polyvinyl butyral, polyvinyl formal, poly(meth)acrylate, polyvinyl acetate, polyamide, polyacrylonitrile, and cellulose acetate, which are thermoplastic resins that do not contain halogen elements. , ethyl cellulose, nitrocellulose, and the like have been disclosed as adhesives in which epoxy resin is added.

[0003] Bonded members coated with these adhesives are heated for a short period of time to form a pregel and become temporarily bonded, so even if the bonded members are bent, cut, degreased, washed, treated with acid, etc., the adhesive remains. It is characterized by the fact that it does not fall off or scatter, and it does not cause contamination of the work area or processing liquid by the adhesive.

0004

[Problem to be Solved by the Invention] However, among the adhesives mentioned above, when adhesives containing polyvinyl chloride are used under high-temperature conditions such as during curing or spot welding, the gas generated when the polyvinyl chloride decomposes corrodes the steel plate. It may be done. In addition, with adhesives containing thermoplastic resins that do not contain halogen elements, the adhesive force may decrease as the amount added increases, and properties such as heat-resistant adhesion and water-resistant adhesion may decrease depending on the properties of the thermoplastic resin added. Sometimes.

[0005]

[Means for Solving the Problems] Therefore, the present inventors have solved the problems of the above-mentioned conventional epoxy resin adhesives,
The present invention was completed after repeated studies to obtain an adhesive composition that has a pre-gelling function and also has excellent adhesive strength, heat-resistant adhesive strength, and water-resistant adhesive strength after heat curing.

That is, the epoxy resin adhesive composition of the present invention comprises (A) 100 parts by weight of an epoxy resin that is liquid at room temperature;
(B) 1 to 80 parts by weight of a curing agent for heat curing, (C) 10 to 1 part by weight of a powdered aromatic thermoplastic resin having a glass transition temperature of 120°C or higher and an average particle size of 200 μm or less
00 parts by weight.

The epoxy resin as component (A) used in the present invention is not particularly limited as long as it is liquid at room temperature, but it usually has a viscosity of 50,000 to 500,000 centipoise at 25°C. In addition, it is preferable to use an epoxy resin with a relatively low molecular weight of about 200 to 1000, and the epoxy equivalent is about 100 to 500, with a weight average molecular weight of about 100 to 1000.
Those having an average of 1.5 or more epoxy groups, preferably an average of 2 or more epoxy groups in the molecule are preferably employed. Specific examples of the epoxy resin to be used include glycidyl type, bisphenol type, hexahydrobisphenol type, novolac type, dimer acid type epoxy resins, and these can be used alone or in combination of two or more types. . Note that an epoxy resin that is solid at room temperature may be optionally mixed as long as it does not impede the properties of the epoxy resin adhesive composition of the present invention and does not cause an extreme increase in solution viscosity. can.

[0008] As the curing agent for heat curing as component (B) in the composition of the present invention, a curing agent for an epoxy resin can usually be used. Specifically, curing agents such as dicyandiamide type, imidazole type, phenol type, acid anhydride type, acid hydrazide type, fluorinated boron compound type, amine imide type, and amine type are mentioned;
Alternatively, two or more types can be used in combination. The curing agent is added and mixed in an amount of 1 to 80 parts by weight, preferably 3 to 40 parts by weight, per 100 parts by weight of the epoxy resin as the component (A). If the amount added is less than 1 part by weight, the curing of the epoxy resin may not be sufficient, and if it is added in excess of 80 parts by weight,
A large amount of unreacted functional groups may remain, making it difficult to carry out the crosslinking reaction smoothly.

Furthermore, if the above-mentioned component (B) alone is not sufficient for curing and the curing temperature needs to be lowered or the curing time becomes longer, a curing accelerator that is usually used within the range that does not impair storage stability may be used. It is preferable to add an agent. Preferred curing accelerators include, for example, alkyl-substituted guanidine-based, 3-substituted phenyl-1,1-dimethylurea-based,
Examples of curing accelerators include imidazole-based, imidazoline-based, tertiary amine-based, monoaminopyridine-based, and amineimide-based curing accelerators. The preferred amount is 20 parts by weight or less, preferably 1 to 10 parts by weight, based on 100 parts by weight of the epoxy resin as component (A).

The thermoplastic resin added as component (C) to the adhesive composition of the present invention is a powdery aromatic resin having an average particle size of 200 μm or less, preferably in the range of 0.1 to 30 μm. It is resin. If a powder with an average particle size of more than 200 μm is used, the pre-gelation rate may be slow,
In some cases, the thermoplastic resin powder dispersed in the composition may settle during storage and cause a separation phenomenon, resulting in a lack of uniformity. In addition, it is preferable to use aliphatic thermoplastic resins such as polymethyl methacrylate, polyvinyl butyral, and polyvinyl formal because the heat resistance of the cured resin will decrease and the temporary adhesive strength will be insufficient. do not have. The powdered thermoplastic resin of the present invention may be of an internally filled type or a hollow type as long as it is within the above average particle size range, and may be a single particle powder or a powder of a plurality of particles aggregated. You can.

Furthermore, in the present invention, the thermoplastic resin has a glass transition temperature (hereinafter referred to as Tg) from the viewpoint of compatibility with the epoxy resin, complete solubility or partial solubility upon heating, and maintenance of heat-resistant adhesive properties. Adopt one with a temperature of 120°C or higher.

Examples of such thermoplastic resins include polysulfone, polyethersulfone, polyarylate, polycarbonate, polyetheretherketone, polyallylsulfone, polyphenylene oxide, polyetherimide, and polyphenylene sulfide. Among these resins, it is preferable to use at least one of polysulfone, polyethersulfone, polyarylate, polycarbonate, polyallylsulfone, and polyetherimide from the viewpoint of pregelling properties and adhesive properties.

The thermoplastic resin is blended in an amount of 10 to 100 parts by weight, preferably 15 to 85 parts by weight, based on 100 parts by weight of the epoxy resin as component (A). If the blending amount is less than 10 parts by weight, it may not be possible to sufficiently pre-gel by short-term heating, resulting in insufficient temporary adhesion.On the other hand, if the blending amount exceeds 100 parts by weight, the epoxy resin This is undesirable because it interferes with its own functions such as heat curability and adhesive properties, increases the viscosity of the adhesive composition, and impairs coating workability.

The above-mentioned powdery aromatic thermoplastic resin can be obtained, for example, by the following method.

■Mechanical pulverization using a ball mill, jet mill, etc. ■Spray dry method. ■A method in which a polymer is dissolved in a solvent at a high temperature above the glass transition temperature or melting point, and then cooled to crystallize the polymer. (2) A method in which a polymer is precipitated by adding and mixing a solvent that is a poor solvent for the polymer and is compatible with the polymer's solvent to a polymer solution obtained by dissolving the polymer in a solvent. ■ A polymer solution obtained by dissolving a polymer in a solvent is added and mixed into a solvent that is a poor solvent for the polymer and is incompatible with the solvent for the polymer, and then strongly stirred to form an emulsion. How to remove polymers by removing them.

The epoxy resin adhesive composition of the present invention has the above-mentioned structure, and may optionally contain silica, clay, gypsum, calcium carbonate, barium sulfate, quartz powder, glass fiber, kaolin, mica, alumina. , hydrated alumina, aluminum hydroxide, talc, dolomite, zircon, titanium compounds, molybdenum compounds, antimony compounds, and other fillers, pigments, anti-aging agents, and other optional additive components are appropriately blended according to the purpose and use. can do. In addition, in order to weld the parts to be joined by spot welding etc., copper, zinc, nickel, cadmium, stainless steel, aluminum, silver, etc., preferably zinc, nickel,
It is also possible to add conductivity to the composition of the present invention by blending metal powders of stainless steel and aluminum.

The composition of the present invention containing each of the above components can be uniformly dispersed at room temperature using a roll, mixer, Henschel mixer, ball mill, kneader, disper, etc.
The compositions of the present invention can be obtained by mixing.

The epoxy resin adhesive composition of the present invention is
At room temperature, the powdered thermoplastic resin (C) is (
A) It is insoluble in the liquid epoxy resin that is the component, but under high temperature conditions, the thermoplastic resin completely dissolves or begins to partially dissolve in the liquid epoxy resin, and when it is cooled to room temperature again, it becomes prepreg-like or high-temperature. It becomes a putty-like consistency. Pre-gelling in the present invention means such a state, and normally, the product in this state is non-tacky and has the property of being dry to the touch.

[0019] The heating conditions required for the above-mentioned pre-gelation change as needed depending on the type and amount of each component, but usually 100°C for several minutes and 120°C for about 1 minute are optimal.

[0020]

EXAMPLES The epoxy resin adhesive composition of the present invention will be specifically explained below. In addition, hereinafter, parts in the text mean parts by weight.

Examples 1-2 and Comparative Examples 1-2 Bisphenol A epoxy resin (epoxy equivalent: about 190, weight average molecular weight: 380, viscosity: 125 poise (25°C)) 10
0 parts, dicyandiamide (curing agent) 10 parts, 3-(3,
6 parts of 4-dichlorophenyl)-1,1-dimethylurea (hardening accelerator) was kneaded in a mixing pot at room temperature for 1 hour, and passed through three rolls to obtain an epoxy resin composition.

On the other hand, polysulfone (product name: Udel P
-3500, manufactured by Amoco Co., Ltd., Tg 189° C.), and a resin in the form of spherical fine particles with an average particle diameter of about 6 μm was obtained by the method (2) above. Incidentally, a scanning electron micrograph of the structure of the obtained resin particles is shown in FIG. Next, the above epoxy resin composition and particulate resin were mixed in the proportions shown in Table 1 to prepare Example 1.
Epoxy resin adhesive compositions of Comparative Examples 1 and 2 and Comparative Examples 1 and 2 were obtained.

Examples 3 to 4 and Comparative Example 3 Except for using polyether sulfone (trade name: Victrex 100P, manufactured by ICI Corporation, Tg 225°C) as the aromatic thermoplastic resin in Example 1, A resin in the form of spherical fine particles with an average particle diameter of about 8 μm was obtained in the same manner as in Example 1, and mixed in the proportions shown in Table 2 in the same manner as in Example 1 to obtain Example 3.
4 and Comparative Example 3 were obtained.

Examples 5 to 6 and Comparative Example 4 In Example 1, amorphous polyarylate (trade name: U Polymer (U-100), manufactured by Unitika Co., Ltd.,
A resin in the form of spherical fine particles with an average particle diameter of about 10 μm was obtained in the same manner as in Example 1, except that a resin with a Tg of 203° C. was used, and this was mixed in the proportions shown in Table 3 in the same manner as in Example 1. 5
Epoxy resin adhesive compositions of -6 and Comparative Example 4 were obtained.

Examples 7 to 8 and Comparative Example 5 In Example 1, polyetherimide (
A resin in the form of spherical fine particles with an average particle size of about 15 μm was obtained in the same manner as in Example 1, except that a product (trade name: Ultem 1000, manufactured by GE Plastics, Tg 217°C) was used. Epoxy resin adhesive compositions of Examples 7 to 8 and Comparative Example 5 were obtained by mixing in the proportions shown in Table 4.

Examples 9 to 10 and Comparative Example 6 In Example 1, polyallylsulfone (trade name: Radel A-100, manufactured by Amoco, Tg22) was used as the aromatic thermoplastic resin.
A resin in the form of spherical particles with an average particle size of about 8 μm was obtained in the same manner as in Example 1, except that 0°C) was used, and the resin was mixed in the proportions shown in Table 5 in the same manner as in Example 1. Epoxy resin adhesive compositions 9 to 10 and Comparative Example 6 were obtained.

Examples 11-12 and Comparative Example 7 Bisphenol A epoxy resin (epoxy equivalent: about 190, weight average molecular weight: 380, viscosity: 125 poise (25°C)) 10
0 parts and 15 parts of adipic acid dihydrazide (curing agent) were kneaded in a mixing pot at room temperature for 1 hour, and then passed through three rolls to obtain an epoxy resin composition.

On the other hand, polycarbonate (trade name: Noryllexan, manufactured by GE Plastics Co., Ltd., Tg 145°C)
A resin in the form of spherical fine particles with an average particle diameter of about 3 μm was obtained using the method described in (1) above.

Next, the above epoxy resin composition and particulate resin were mixed in the proportions shown in Table 6 to prepare Examples 11-12.
And an epoxy resin adhesive composition of Comparative Example 7 was obtained.

Comparative Example 8 The average was obtained in the same manner as in Example 1, except that phenoxy resin (trade name: UCAR phenoxy resin PKHH, manufactured by Union Carbide, Tg 100°C) was used as the aromatic thermoplastic resin in Example 1. Resin in the form of spherical fine particles with a particle size of about 6 μm was obtained, and mixed in the same manner as in Example 1 in the proportions shown in Table 7 to obtain an epoxy resin adhesive composition of Comparative Example 8.

Comparative Example 9 Polymethyl methacrylate resin (trade name: Sumipec-B,
A resin in the form of spherical fine particles with an average particle diameter of about 3 μm was obtained in the same manner as in Example 1, except that a resin (manufactured by Sumitomo Chemical Co., Ltd., Tg 105°C) was used, and the resin was mixed in the proportions shown in Table 7 in the same manner as in Example 1. and mixed to obtain an epoxy resin adhesive composition of Comparative Example 9.

Comparative Example 10 The same procedure as in Example 1 was carried out except that polyvinyl butyral resin (trade name: Denka Butyral, manufactured by Denki Kagaku Kogyo Co., Ltd., Tg 80°C) was used instead of the aromatic thermoplastic resin in Example 1. Fine particulate resin having an average particle diameter of about 20 μm was obtained, and this was mixed in the same manner as in Example 1 in the proportions shown in Table 7 to obtain an epoxy resin adhesive composition of Comparative Example 10.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

[Table 6]

[0039]

[Table 7]

The properties of the epoxy resin adhesive compositions obtained in each of the above Examples and Comparative Examples were measured according to the test method shown below, and the results are also shown in each table.

<Pre-gelatability> Each composition was coated on an iron plate to a thickness of 3
mm, and left in a hot air oven kept at 120°C for 3 minutes, then cooled to room temperature. At this time, the degree of stickiness of the prepreg surface and removability from the iron plate were judged using the following criteria. did. ○: Dry to the touch and can be peeled off into a sheet. △: Stickiness remains, and some of it remains when peeled off. ×: Remains liquid and cannot be peeled off.

<Temporary adhesive strength> Each composition was applied to a steel plate (SPC
C-SD: 100 x 25 x 1.6 mm) with adhesive area of 25
×12.5mm, layer thickness 0.12mm, 120℃
A test piece was prepared by temporarily bonding in a hot air oven for 3 minutes. The shear adhesive strength of these test pieces was measured using a Tensilon tensile tester (tensile speed 5
mm/min, measurement temperature 20°C).

<Shear adhesive strength> Measurement was carried out in accordance with the measurement of the temporary adhesive strength described above. However, the heating conditions were 150°C x 60 minutes.

<Heat-resistant adhesive strength> Measurement of adhesive strength was carried out in accordance with the above-mentioned measurement of adhesive strength. However, the measurement temperature is 80℃, 120℃, 150℃
The retention rate (%) with respect to the adhesive force at 20° C. was defined as the heat-resistant adhesive force, and it was calculated using the following formula. Retention rate (%) = (adhesive strength at each measurement temperature) x 100 /
(Adhesive strength at 20℃)

<Water-resistant adhesive strength> A test piece was prepared according to the above adhesive strength measurement, and the adhesive strength was measured after immersing it in 40°C warm water for 2 weeks, and the retention rate (%) with respect to the initial adhesive strength was calculated. The water-resistant adhesive strength was calculated using the following formula. Retention rate (%) = (adhesive strength after immersion in hot water) x 100 / (
initial adhesive strength)

[0046]

Effects of the Invention As described above, the epoxy resin adhesive composition of the present invention has a specific amount of a curing agent and a specific powdered aromatic thermoplastic resin added to a liquid epoxy resin. It has excellent temporary adhesion properties.
Furthermore, after heat curing, the adhesive has excellent adhesive strength, heat-resistant adhesive strength, and water-resistant adhesive strength.

[Brief explanation of the drawing]

FIG. 1 is a scanning electron micrograph (600x magnification) showing the particle structure of the thermoplastic resin powder used in Example 1.

Claims (2)

[Claims] Claim 1: (A) Epoxy resin 10 that is liquid at room temperature
0 parts by weight, (B) 1 to 80 parts by weight of curing agent for heat curing, (
C) Glass transition temperature is 120°C or higher and 200μ
An epoxy resin adhesive composition comprising 10 to 100 parts by weight of a powdered aromatic thermoplastic resin having an average particle size of m or less. 2. The epoxy resin adhesive composition according to claim 1, wherein the aromatic thermoplastic resin is at least one selected from polysulfone, polyethersulfone, polyarylate, polycarbonate, polyallylsulfone, and polyetherimide.