JPS6281445A - Bondable epoxy composition - Google Patents

Abstract

PURPOSE:To obtain a bondable compsn. which retains excellent characteristics inherent to epoxy resins and has a sufficient strength capable of being handled by robots even when it is in the form of an uncured article, by adding a small quantity of a specified thermoplastic material to a specified solid epoxy resin. CONSTITUTION:A bondable compsn. comprises 100pts. epoxy resin (a) having a m.p. of 50-150 deg.C, 1-33pts. thermoplastic material (b) having a m.p. of 20-180 deg.C, wherein the product of tensile elongation [%] at break and tensile strength [kg/cm<2>] at break is 1X10<3>-250X10<3>[%.kg/cm<2>] and a hardener (c) for the epoxy resin. The term 'uncured' as used herein includes a state where crosslinking is not proceeding at all and a state where crosslinking is partially proceeding but not completed. Examples of the epoxy resin are bisphenol type epoxy resins having an average MW of 500 or above. Examples of the thermoplastic material are vinyl chloride resins, ABS resins, (meth) acrylate resins, urethane elastomers, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an adhesive epoxy composition, which is used, for example, as an adhesive or a sealant.

(Conventional technology) Epoxy resin adhesives are usually in liquid form, but ■ Because they are liquid, measurement accuracy is poor and it is difficult to apply them to small quantities and precise areas ■ Pot life is 2 to 3 There are many problems such as: ■ The work environment is dirty ■ Liquids cannot be shaped and cannot be handled by robots.

On the other hand, powdered epoxy adhesives using solid epoxy resin are also known, but their mechanical strength in an uncured state is weak. Therefore, when molding into a certain shape and using it as an adhesive, the powder is pressed and used, but the molded product is too fragile to be handled by robots or the like. Moreover, the shape is also limited to a simple one.

Another attempt was made by mixing an epoxy resin with an adhesive thermoplastic resin as shown in Japanese Patent Application Laid-Open No. 55-90549.
A so-called hot melt adhesive with improved heat resistance has been proposed, but this requires the use of a large amount of thermoplastic resin in order to maintain its shape.
The amount of epoxy resin needs to be 300 parts by weight or less relative to 0 parts by weight. That is, for 100 parts by weight of epoxy resin, it was necessary to use 33.3 parts by weight of thermoplastic resin.

However, although this improved the heat resistance of hot melt adhesives, it was difficult to fully demonstrate the excellent features of epoxy resins.

(Problems to be Solved by the Invention) The purpose of the present invention is to maintain the excellent features of epoxy resins, such as adhesiveness, heat resistance, chemical resistance, electrical insulation, etc. IIkAn object of the present invention is to provide an adhesive composition which is a dense molded body and has sufficient strength to be handled by a robot or the like.

(Means for solving the problem α) The present invention uses 100 parts of an epoxy resin with a melting point of 50 to 150°C, a melting point of 20 to 180°C, and an elongation at breakage [
%] and the tensile strength at break [kg/cm2] is IX
103-250X 10' C%・kg/cII12
] An adhesive epoxy composition characterized by containing 1 to 33 parts of a thermoplastic substance and a curing agent for epoxy resin.

In other words, by adding a small amount of a specific thermoplastic substance to a specific solid epoxy resin, it is possible to make the solid epoxy resin strong without impairing its properties, which has traditionally been a problem due to its extremely brittle properties. This is what we discovered that can be done.

The composition of the present invention can be easily molded even in an uncured state, and the molded product is strong and will not be deformed when handled by a robot or the like, and the molded product and the adherend can be physically bonded. By heating the molded product in the assembled or fitted state, the molded product can be melted and welded to the object to be adhered, and then cured and bonded. In the present invention, the uncured state refers to a state in which crosslinking has not progressed at all. It also includes a state in which crosslinking has progressed to a certain extent but has not been completed.

Examples of the epoxy resin of the present invention having a melting point of 50 to 150 DEG C. include bisphenol type epoxy resins having an average molecular weight of 500 or more. In addition to these, there are cresol novolac type epoxy resins, 7E/-crucible type epoxy resins, and halogenated or hydrogenated products of these. In addition, imide, amide, urethane, silicone-modified epoxy resin and JP-A-60-92
Also included are high molecular weight polyfunctional epoxy resins such as those disclosed in US Pat. Moreover, these can also be used as a mixture. If the melting point of the epoxy resin is less than 50°C, it is difficult for the composition according to the present invention to remain solid at room temperature, and if it exceeds 150°C, a higher temperature is required to melt the composition according to the present invention, which is impractical. .

On the other hand, in order to effectively reinforce the epoxy resin with the addition of a small amount of thermoplastic substances, elongation at tensile break [%
] and the tensile strength at break (kg/cva2) is preferably larger. This product is related to fracture energy and is hereinafter referred to as E [%·kg/cω2]. Here, if the strength at tensile break is high but the elongation at tensile break is small, the value of E will be small, making it hard and brittle, and the reinforcing effect will be small.

Conversely, materials with high elongation at tensile break but low strength at tensile break also have a small E value and are flexible but easily deform and have a small reinforcing effect. From the above, the value of E is 1×103
%・kg/cm' or more, there is a reinforcing effect. Also E
It is desirable that the value of is larger, but 250X10'%・kg
/cIo2 generally has a high melting point, resulting in poor meltability of the composition of the present invention. Melting of thermoplastic, α
must be between 20 and 180°C. If the melting point is less than 20"C, it is difficult for the composition of the present invention to maintain a solid state at room temperature, and if it exceeds 180C, it is not practical because a higher temperature is required to melt it.

In the present invention, the thermoplastic material is epoxy resin 10
1 to 33 parts are used per 0 parts (weight parts, the same applies hereinafter). If the amount is less than 1 part, the reinforcing effect will be small, and the uncured molded product will be brittle and difficult to maintain its shape. On the other hand, if the amount exceeds 33 parts, the characteristics of the cured epoxy resin, such as heat resistance, solvent resistance, and moisture resistance, will be seriously impaired, making it impossible to achieve the object of the present invention.

Examples of thermoplastic substances that satisfy these conditions include vinyl chloride, polystyrene, ABS resin, (meth)acrylic resin, polyethylene, polypropylene, polyester elastomer, polybutadiene elastomer, vinyl chloride elastomer, chlorinated polyethylene, and styrene. Examples include elastomers, polyolefin elastomers, polyamide resins, urethane elastomers, fluorine elastomers, polyvinyl alcohol, and polyvinyl acetate.

Next, as the curing agent used in the present invention, various known compounds can be mentioned, and for example, amines, acid anhydrides, phenols, etc. can be used. Specific examples of amines include diethylenetriamine, triethylenetetramine, bis(hexamethylene)triamine, 1-limethylhexamethylenediamine, mensenecyamine, isophoronediamine, metaxylylenediamine, 3,9-bis(
3-aminopropyl)-2,4,8-tetraspiro(5
, 5] undecane, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, 4.
Specific examples of acid anhydrides such as 4'-methylenebis(2-chloroaniline) and adducts thereof with epoxy resins include 7-talic anhydride, trimetic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, Specific examples of phenols include maleic anhydride, tetrahydro-7-talic anhydride, hexahydro-7-talic anhydride, methylnadic anhydride, methylcyclohexenetetracarboxylic anhydride, tetrachloro-7-talic anhydride, tetrabromo-7-talic anhydride, etc. , phenol, 0-cresol novolac,
Examples include phenol novolak and phenol aralkyl. The amount of the curing agent to be blended is preferably in the range of 0.5 to 2 in terms of equivalent ratio to the epoxy group.

Further, in the present invention, various known additives can be added. For example benzyldimethylamine, 2.4.6-)
Tertiary amines such as lith(dimethylaminomethyl)phenol, piperinone, pyridine, picoline, and 2-ethyl-
imidazoles represented by 4-methyl imiguzole,
Others 1.8-') Lewis acids such as azabicyclo[5,4,0]undecene and Br3, dicyandiamide, amine imide, organic acid hydrazide, etc., mixtures of these, salts, complexes, etc. catalyst, mica,
Inorganic fillers such as silica, lath fiber, lath 7 lake, glass powder, carbon fiber, talc, calcium carbonate, organic fillers such as aramid fiber and nylon fiber, carbon black, benzene, titanium white, cyanine Pigments and dyes such as blue, lubricants such as wax and zinc stearate, other silane coupling agents, viscosity modifiers, etc. can be added as necessary.

The adhesive epoxy composition of the present invention can be obtained by mixing and kneading an epoxy resin, a thermoplastic material, a curing agent, an additive, etc. The composition of the present invention can be used, for example, in an uncured state by injection molding, extrusion molding, compression molding, transfer molding, etc.
By molding by means such as casting, it is possible to obtain a molded product having sufficient strength to withstand handling by a robot or the like at room temperature. The shape of the molded product can be any arbitrary shape, such as a rod, a flat plate, a ring, a tube, a branched pipe, a cup, a sheet, a film, a hollow pipe, a pellet, or a half-shape. Examples of shapes include a donut shape and a frame shape. The molded body is used, for example, by placing it, inserting it, and fitting it into the bonded part of the parts to be bonded, and then heating it to a temperature of -lx above the melting point of the molded body, so that the molded body melts and adheres and further hardens.

Further, it is also possible to place the molded product on a portion or the entire surface of the part to be adhered at the same time as molding, and then melt and bond the molded product and further harden it.

(Effects of the Invention) According to the molded article obtained from the composition of the present invention, quantitative control of adhesive (=volume), positioning (=shape) of objects to be adhered,
It is also adaptable to automation such as robots (solid, high strength), and assembly by adhesive is extremely easy. Furthermore, since the main component is epoxy resin, it has excellent heat resistance, chemical resistance, solvent resistance, electrical properties, adhesion, adhesion, etc.

(Example) j Examples and comparative examples will be given and explained below. In addition, "parts" in the river mean parts by weight.

Examples 1 to 4 and Comparative Examples 1 to 4 The ingredients shown in Table 1 were melt-mixed in a twin-screw kneading extrusion mill and formed into pellets. This is then molded using an extrusion molding machine in a substantially uncured state. : A film having a thickness of 1I6111 was prepared and cut into a shape of IOX 12.5++++Il. This film was sandwiched between two sheets of mild steel (SS41) with clips, placed in an oven at 180° C., and heated for 5 hours to melt and bond. Table 2 shows the shear tensile adhesive strength at 25°C and 120°C.

On the other hand, the pellet of the first composition was molded into a flat plate having a thickness of +5X 15X 1 ++IIn using an injection molding machine in a substantially uncured state. After placing the molded article 11 on the electronic component chip component installed on the printed circuit board 2, it was placed in an oven at 180 ° C. After 5 minutes, it was completely melted and the electronic component was sealed. It was cured after 5 hours.

Table 2 shows the change in appearance when a heated hanging iron was directly touched on this cured product for 10 seconds, and the sticky state when the surface was strongly rubbed with a cloth soaked in acetone.

As is clear from Table 2, according to the present invention, the cured product has the original characteristics of an epoxy resin, can be molded in a substantially uncured state, and can be molded at temperatures of 180°C or lower. It becomes possible to melt it completely.

In Comparative Example 1, since the blended amount of thermoplastic substance was large, the heat resistance of the cured product was poor, the adhesive strength at 120° C. was small, and it could not withstand the temperature of a heated hanging iron. Also, the solvent resistance is not good because acetone causes stickiness.

Although the cured product in Comparative Example 2 has the characteristics of an epoxy resin, it has poor meltability and is unsuitable for melt adhesive curing, which is the objective of the present invention.

Comparative Example 3 could not maintain its shape at room temperature, and Comparative Example 4 was too brittle to be taken out as a molded product.

(that's all)

Claims (1)

[Claims] (1) 100 parts of an epoxy resin with a melting point of 50 to 150°C,
Melting point is 20-180℃ and elongation at tensile break [%
] and the tensile strength at break [kg/cm^2] is 1×
An adhesive epoxy composition comprising 1 to 33 parts of a thermoplastic material of 10^3 to 250 x 10^3 [%.kg/cm^2] and a curing agent for epoxy resin.