JPH0463115B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Purpose of the invention [Field of industrial application] The present invention relates to an epoxy resin-based thermosetting adhesive composition, which can be applied to, for example, metals, glass, ceramics, wood, and heat-resistant plastics. It is widely used in various industries because it can be used for adhesive bonding of various base materials. [Prior Art] Epoxy resin thermosetting adhesives are widely used in many fields due to their excellent properties. However, with conventional adhesive compositions of this type, it is difficult to apply them to the base material in a hot molten state, and it is also difficult to process them into arbitrary shapes, which limits the way they can be applied. The target is limited. In other words, thermosetting adhesives have characteristics such as high adhesive strength, high adhesive heat resistance, and excellent adhesive durability, and the typical epoxy adhesive is widely used in various fields. has been
Among them, one-component epoxy adhesives have high reliability in adhesive performance and are easy to manage during use, so they are often applied to adhesive bonding lines as industrial adhesives, but conventional adhesives of this type The agent has been tested in liquid, paste, and film forms, and has the following drawbacks. In the case of the above liquid and paste adhesives,
Coating to the substrate can be done relatively easily at room temperature or under slight heating, but because the adhesive has fluidity and stickiness, it is difficult to store and handle the substrate after coating. , dirt during the adhesion process,
There is a risk that problems such as spillage, adhesion to other objects, and adhesion to workers may occur. In addition to the above, when a solvent is used, there are sanitary problems due to volatilization of the solvent. In the case of the above-mentioned film adhesive, cutting, positioning, and fixing operations according to the shape are essential in the pasting process to the base material, but these operations are difficult to implement with equipment and require many manual efforts. The problem is that you have to rely on it. Furthermore, since these adhesives are essentially obtained based on a mixture of liquid epoxy resin and a hardening agent or a solution mixture of an epoxy resin and a hardening agent, the reaction between the epoxy resin and the hardening agent does not occur at room temperature. It is common sense to store the adhesive in a sealed container at a low temperature, and long-term heating coating is difficult because the adhesive will deactivate, especially with adhesives that harden quickly under heat. That's true. As described above, it is common knowledge among those skilled in the art that conventional adhesives of this type, especially adhesives with a fast curing speed, cannot be melt-coated onto a base material. Due to the heat, attempts at melt coating and the development of compositions suitable for melt coating were made.
It had not been done at all. In other words, epoxy resin functions as an adhesive by polymerizing and polymerizing by opening the oxirane ring. In this case, the reaction involves the oxirane ring, which is a three-membered ring with a high degree of strain energy. Since it is a ring-opening reaction, the activation energy of the polymerization reaction of epoxy resin is, for example, around 10 Kcal/mol in the reaction of a typical bisphenol A type epoxy resin and an acid anhydride.
10~ by reaction with the same epoxy resin and amine
Low at 18Kcal/mol. The activation energy of the reaction between alkyl phenol and formaldehyde, such as the polymerization of phenolic resin, is 20 to 24 Kcal/mol,
In the thermal polymerization initiation reaction of styrene, 32 Kcal/mol,
It can be seen that the activation energy for the polymerization reaction of epoxy resins is low even when compared to the thermal decomposition of azo compounds of 27 to 40 Kcal/mol and the thermal decomposition of organic peroxides of approximately 30 Kcal/mol. This low activation energy means that the temperature dependence of the reaction rate is low, indicating that the reaction progresses at low temperatures even in systems that are completely cured at high temperatures. In fast combinations, reactions proceed even at fairly low temperatures. Even from this theoretical background, it is generally unconventional to apply one-component epoxy adhesives under heating;
Even for epoxy one-component adhesives that cure at temperatures above, it is common sense to store them at a low temperature below room temperature, usually below 4℃, and it is conventional to apply this type of adhesive composition in a molten state. This had not been thought of at all, and no compositions capable of such melt coating had been developed at all. In addition to the above-mentioned circumstances, conventional adhesives of this type, especially adhesives with a fast curing speed, are relatively unstable when heated as mentioned above, making it difficult to melt the composition and shape it. . As described above, it is difficult to process conventional compositions of this type into various shapes, so it is difficult to supply them as adhesives in various shapes, and they cannot be used depending on the shape of the parts to be bonded. Therefore, its uses are limited. [Problems to be solved by the invention] As mentioned above, it is difficult to apply this type of conventional adhesive, especially an adhesive with a fast curing speed, to a base material in a hot molten state, so the method of application is difficult. limited,
For example, it cannot be applied quickly and with good meterability like hot melt adhesives, and it is difficult to process it into arbitrary shapes, which limits its uses and applications. The present invention has been made to solve the problems of conventional adhesives, and the purpose of the present invention is to be stable, capable of melt coating on base materials, and capable of being applied in various shapes. Therefore, roll coating and other coating equipment similar to hot melt adhesives can be used, and rapid coating with good metering is possible, as well as fast curing speed and ease of handling. It is an object of the present invention to provide an advantageous adhesive composition that has good storage stability and a wide range of uses. (B) Structure of the invention [Means for solving the problems and their effects] The adhesive composition of the present invention comprises (A) a bisphenol-type epoxy resin that is solid at room temperature, and (B) at room temperature. liquid and at least 1 per molecule
(C) a carboxylic acid hydrazide having a melting point within the range of 150 to 250°C; and (D) an onium compound having a group 5B element of the periodic table as a central element. It is characterized by Due to the composition described above, this adhesive composition can exhibit an effect that meets the above-mentioned purpose. That is, according to the present invention, it is possible to provide an adhesive composition that melts at, for example, 60 to 120° C. and is stable for a long time in a fluid state with a relatively low viscosity of 50 to 500 Pascal·sec. Such compositions can be applied to substrates in a variety of ways in a low temperature molten state;
It can be used in the same coating equipment as hot melt adhesives, and in particular, it is also possible to employ a method in which the composition is roll coated onto a substrate between two or more rolls in a hot melt state. Conventionally, hot-melt adhesives that utilize the heat-melting and cooling-solidifying properties of thermoplastic resins have features such as ease of installation, cleanliness after installation, hygiene, and short-time adhesion, and have been used as industrial adhesives. Although it has become widely used in recent years as it has excellent adhesion line suitability, conventional epoxy resin adhesives, especially adhesives with a fast curing speed, are difficult to melt and apply as described above. However, although the adhesive composition of the present invention has a fast curing speed, it can be applied to a substrate by a method similar to that of a hot melt adhesive as described above. Further, since the adhesive composition of the present invention becomes a solid state with no tackiness by cooling or cooling after coating, the substrate coated with the composition of the present invention is easy to store and handle. After incorporating the coated base material into the part to be bonded, the adhesive composition of the present invention can be newly applied, for example, by
By heating at a temperature below 200℃, it can be heated for several minutes.
Since curing and adhesion can be easily performed in several tens of minutes, automation of the adhesion process can be achieved by configuring a line configuration. Furthermore, according to the present invention, it is possible to obtain a composition that maintains a stable molten state as described above despite its fast curing speed, and therefore can be melt-processed. Therefore, it can be used in various forms. For example, it can be supplied as an adhesive in the form of a film, sheet, rod, fiber, etc., and in this case, unlike conventional film-like epoxy adhesives, it is obtained as an adhesive with no tackiness (see above). Advantageous in terms of adhesive handling and other aspects. for example,
The composition of the present invention processed into a film adhesive has good storage stability at room temperature, and conventional film epoxy adhesives are made by blending an epoxy resin and a hardening agent in a liquid or solution state. Because it is made into a solid film by impregnating it with water, drying and semi-curing (B stage), there are problems with storage stability and the need for refrigerated or frozen storage. Because it remains sticky, the film itself is made into a product through release paper, etc., and even after it is pasted, it cannot be laminated or stocked.Furthermore, the film must be cut to match the shape of the adherend and positioned. This solves the problem that the pasting operation is difficult to perform mechanically and requires a lot of manual work, and the film-like adhesive obtained from the composition of the present invention can It is easy to store and handle, and
Since it can be processed into various shapes in a molten state, it is of course easy to match the film to the shape of the adherend, and it is also possible to mechanize the bonding process. Furthermore, the composition of the present invention is not only in the form of a film, but also can be melted and processed into any shape, so it can be supplied as a solid adhesive in various shapes, and can therefore be applied to various shapes of joints. can. It can also be crushed into granules or powder. Next, each component of the adhesive composition according to the present invention will be explained. (A) Bisphenol-type epoxy resin that is solid at room temperature (25°C) The bisphenol-type epoxy resin, which is one of the components of the adhesive composition in the present invention, is solid at room temperature (25°C). be. This bisphenol type epoxy resin has one or more oxirane groups in one molecule, and has the following general formula - (1)
This is shown in . However, in formula 1 (1), (A: hydrogen or alkyl group X:

[Formula] or

[Embodiments of the invention]

Some embodiments of the present invention will be described below. It should be noted that, as a matter of course, the present invention is not limited only to the following examples. Comparative examples are also shown. Example 1 As an epoxy resin, a bisphenol A type epoxy resin Epicoat 1002 (trade name, manufactured by Yuka Ciel Epoxy Co., Ltd.) has an average molecular weight of 1060 and is solid at room temperature.
Epoxy equivalent average 650) 100 parts by weight, Bisphenol A type epoxy resin Epicoat 834 (trade name, Yuka Ciel Epoxy Co., Ltd. product. Epoxy equivalent average 250) as an epoxy compound that is liquid at room temperature.
20 parts by weight, sebacic acid dihydrazide (acid hydrazide/oxirane equivalent =
1.05) 28.3 parts by weight, 0.5 parts by weight of benzyltrimethylammonium chloride as an onium compound whose central element is a group 5B element of the periodic table as a curing accelerator, and room-temperature liquid polycaprolactone as a flexibility imparting agent as other ingredients. Resin Plaxel 308 (Product name. Daicel Chemical Industries, Ltd. product. Average molecular weight 850)
Add 8 parts by weight and talcum powder as other additives.
Added 5.0 parts by weight. The mixture with the above composition ratio was processed using a twin-screw extruder equipped with a liquid material press-in device (spindle rotation in the same direction, cylinder diameter 30 mm).
Φ, L/D = 25), and further pulverized to obtain the desired adhesive. The melting point of the obtained adhesive is 60-70℃, the initial viscosity at 80℃ is 200Pa・sec, and the viscosity is 500Pa・sec.
The time it takes for the product to exceed seconds is 10 hours or more (hereinafter, this time is referred to as pot life). This adhesive is
Even after being stored at 40°C for one month, it melts uniformly at 80°C with a viscosity of 320 Pa·s, and has good storage properties. Using the adhesive of this example, we measured the tensile shear strength of a test piece that was hot-press bonded at 160°C for 20 minutes using a commercially available bonded steel plate (0.6 mm thick) as an adherend.
140Kgf/cm ² (steel deformation) at 23℃, 138Kg at 82℃
f/cm ² or more (steel material deformation), it was 18 kgf/cm ² at 160°C, and the T-peel strength was 13 kgf/25 mm at 23°C. The tensile shear strength after leaving the adhesive piece under constant temperature and humidity conditions of 80°C and 95% RH for one month is 137 Kgf/cm ² or more at 23°C (steel material deformation),
Durability was also good. Example 2 and Comparative Examples 1 and 2 Adhesive compositions of Example 2 and Comparative Examples 1 and 2 were manufactured in the same manner as in Example 1 using the compositions shown in Table 1 below. The obtained adhesive was evaluated in the same manner as in Example 1. The results of this evaluation are also shown in Table-1. Comparative Example 1, which does not contain component (C), which is a curing accelerator in the present invention, has low strength, while Comparative Example 2, which uses 2-methylidazole, which is a curing accelerator other than component (C), has low strength. Although it is large, it has a high melt viscosity after storage and a short pot life, making it unsuitable for melt application.

【table】

[Table] The items used in Table 1 other than those mentioned above are as follows. Epicote 828: Manufactured by Yuka Ciel Epoxy Co., Ltd., bisphenol A type epoxy resin that is liquid at room temperature (average epoxy equivalent: 188) Isophthalic acid hydrazide: Melting point 219°C, Table 1
epoxy resin and a hydrazide compound that is incompatible with the epoxy compound at room temperature. In the table, the * mark indicates the deformation of the steel material, and the actual adhesive strength is thought to be higher than the numerical value. Example 3 Bisphenol A type epoxy resin Epicoat, which has an average molecular weight of 900 and is solid at room temperature, as an epoxy resin
1001 (product name: Yuka Ciel Epoxy Co., Ltd. product. Average epoxy equivalent: 475) and bisphenol A type epoxy resin Epicoat 1004 (product name: Yuka Ciel Epoxy Co., Ltd. product. Average molecular weight 1600, solid at room temperature. Epoxy A 67:33 weight ratio mixture with an average equivalent weight of 925), Epicote 828 (described above) as an epoxy compound, isophthalic acid dihydrazide as a curing agent, an equimolar adduct of piperazine and adipic acid (nylon salt) as a curing accelerator, and polyethylene as an additive. Powder Frozen
An adhesive was produced in the same manner as in Example 1 using UF-20 (trade name, manufactured by Seitetsu Kagaku Kogyo Co., Ltd.). Table 2 shows the results of evaluating this adhesive in the same manner as in Example 1.
Shown below. As shown in the table, this example also shows good results.

【table】

[Table] Example 4, Comparative Example 3 Epomiku R-302, a bisphenol A type epoxy resin that has an average molecular weight of about 1000 and is solid at room temperature as an epoxy resin (trade name. Mitsui Petrochemical Epoxy Co., Ltd. product. Epoxy equivalent weight average 650) , adipic acid dihydride, which has a melting point of 181°C as a hardening agent and is incompatible with the epoxy resin shown in Table 2 and the epoxy compound shown in Table 2 at room temperature 25°C, trimethylammonium propionate as a curing accelerator, and a liquid state at room temperature as an epoxy compound. 4
The functional epoxy compound 1,3-bis(N,N
An adhesive was produced in the same manner as in Example 1 using -diglycidylaminomethyl)cyclohexane (epoxy equivalent: 92). This was evaluated in the same manner as in Example 1, and the results are shown in Table 2. From Table 2, it can be seen that good results were obtained in this example as well. As Comparative Example 3, an adhesive was manufactured using a composition that did not contain the above epoxy compound. Table-2
Therefore, this comparative example 3 has a pot life of 0 (immediately
It exhibits a viscosity of 770 Pa·sec), and the melt viscosity after storage is also high, indicating that it is unsuitable for melt application. Example 5 500 g of the adhesive composition of Example 2 was placed in a stainless steel container equipped with a temperature control device, and
Melt stirring was carried out continuously for 10 hours at a temperature of ~85°C, and the mixture could be stirred well without any significant change in viscosity. Even after the work was completed, the contents were well dissolved in methyl ethyl ketone, and no gel or the like was observed. Example 6 The adhesive obtained in Example 1 was roll coated as follows. That is, this adhesive was supplied as a set of a rubber roll and an iron doctor roll to a spreader coating machine (manufactured by Tanouchi Tekko Co., Ltd.) that was capable of hot coating and consisted of two sets of upper and lower heating rolls. ~90
After melting at a roll temperature of ℃, a 20 mm thick plywood was passed through the rubber rolls at a speed of 10 m/min with a spacing of 20 mm, and as a result, the adhesive was evenly coated on both sides of the plywood in an amount of approximately 50 g/ ^m2. We were able to. The plywood coated with adhesive on both sides cooled within a few minutes, could be stocked and laminated without being sticky, and was easy to handle. Example 7 In this example, the epoxy resin used was Epicoat 1001, a bisphenol A type epoxy resin with an average molecular weight of 900 and solid at room temperature (described above; used in Example 3).
and 100 parts by weight of a 67:33 weight ratio mixture of bisphenol A type epoxy resin Epicoat 1004 (described above, also used in Example 3), which is solid at room temperature and has an average molecular weight of 1600, and Epicoat, which is liquid at room temperature as an epoxy compound.
828 (trade name: Yuka Ciel Epoxy Co., Ltd. product. Average epoxy equivalent: 188) 20 parts by weight, isophthalic acid dihydrazide (acid hydrazide/oxirane equivalent), which has a melting point of 219°C and is incompatible with these epoxy resins and epoxy compounds as a curing agent. ratio
An adhesive was obtained in the same manner as in Example 1 using 0.62, 17.1 parts by weight and 0.5 parts by weight of benzyltrimethylphosphonium iodide as a curing accelerator. The melting point of the resulting adhesive is 60~
The temperature was 70°C, the initial viscosity at 80°C was 180 Pa seconds, and the pot life was over 10 hours. This adhesive has a cell size of 3/4 inch paper weight 160g/m ² and a height of 20mm.
As a result of applying the phenol-impregnated paper honeycomb core using a heated spreader, it was possible to successfully apply the adhesive on both end faces of the honeycomb core in an amount of 80 to 120 g/m ² (one side). The coated honeycomb core could be stored and laminated without tackiness after being left to cool. A 50 mm square, 0.6 mm thick bonded steel plate was used as the face material, and in combination with the double-sided coated honeycomb core obtained above, heat bonding was performed at 160℃ for 10 minutes using a heat press, and then the flatwise tensile strength of the honeycomb panel was determined. When measured at ℃, a good value of 11.3 kgf/cm ² was obtained. (c) Effects of the invention As mentioned above, the adhesive composition of the present invention is stable in a molten state despite its fast curing speed under heating, and can be applied to a substrate in a molten state. It can be processed into various shapes and supplied. Therefore, it can be applied as a hot melt adhesive such as a roll coating adhesive, and is an excellent adhesive with good handling and storage properties and a fast curing speed, and has a wide range of uses and can be effectively used in various industries. It has the effect of being able to.

Claims (1)

[Claims] 1. (A) A bisphenol type epoxy resin that is solid at room temperature; (B) A bisphenol type epoxy resin that is liquid at room temperature and contains at least one bisphenol type epoxy resin in one molecule.
(C) a carboxylic acid hydrazide with a melting point in the range of 150 to 250°C; and (D) an onium compound whose central element is an element from group 5B of the periodic table. A thermosetting adhesive composition characterized by: