JPS59145271A - Adhesive composition - Google Patents

Abstract

PURPOSE:To provide an adhesive having greatly improved impact resistance without detriment to instantaneous adhesion, by adding an ethylene/vinyl acetate copolymer resin to an alpha-cyanoacrylate. CONSTITUTION:An adhesive compsn. is obtd. by adding an ethylene/vinyl acetate copolymer resin (A) to an alpha-cyanoacrylate (B) of the formula (wherein R is 16C or lower alkyl, alkenyl, aralkyl, alkoxy-alkyl, haloalkyl, cycloalkyl, phenyl, etc.). When the resin B alone is used as an adhesive, the cohesive force is great and the volume shrinkage during polymn. is large so that there are disadvantages that bonding is hard and brittle and phenomenons such as deformation, peeling, etc. will occur. When the resin A is used together, the impact resistance can be greatly improved. The resin A is used in a quantity of 1-15wt% based on that of the resin B.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to adhesive compositions. More specifically, the present invention relates to an α-cyanoacrylate adhesive composition with improved impact resistance.

α-Cyanoacrylate represented by the general formula (wherein R is alkyl, alkenyl, aralkyl, alkoxyalkyl, haloalkyl, cyclohexyl, phenyl, etc. having 16 or fewer carbon atoms) is extremely susceptible to anionic polymerization, and moisture on the solid surface or in the air It has the property of polymerizing and curing in a short time using anionic active species such as alkaline substances without adding catalysts or heating, so it is widely used as an instant adhesive for bonding rubber, plastics, metals, glass, etc. .

However, when an α-cyanoacrylate adhesive is used alone, it has the drawback that its high cohesive force and high volume shrinkage during polymerization make the adhesive hard and brittle, and phenomena such as deformation and peeling occur. Various methods have been proposed to overcome these drawbacks, including adding plasticizers such as dialkyl phthalates to make the adhesive film flexible, and adding polymerizable vinyl monomers to make the adhesive film more flexible. There are methods to increase adhesive strength and methods to add a copolymer made by graft copolymerizing styrene to a rubber-like polymer as a backbone, but all of these methods are based on the impact resistance of α-cyanoacrylate adhesives. It does not improve the situation.

The present inventors have conducted various studies to improve properties such as impact resistance of α-cyanoacrylate adhesives.

The present inventors have discovered that impact resistance can be significantly improved by adding and using an ethylene-vinyl acetate copolymer to α-cyanoacrylate.

Examples of the α-cyanoacrylate used in the present invention include methyl-α-cyanoacrylate, ethyl-α-cyanoacrylate, propyl-α-cyanoacrylate, butyl-α-cyanoacrylate, allyl-α-cyanoacrylate, and methoxyethyl- α-cyanoacrylate, ethoxyethyl-α-cyanoacrylate, 2-
These include chloroethyl-α-cyanoacrylate, cyclohexyl-α-cyanoacrylate, and the like.

The ethylene-vinyl acetate copolymer resin used in the present invention preferably has a vinyl acetate content of about 50 to 90% by weight. If the vinyl acetate content is less than 50% by weight, it is difficult to dissolve and suspend it in α-cyanoacrylate, resulting in two-layer separation, making it impossible to obtain stable performance.
If the copolymer resin has a high softening point and cannot absorb impact energy, good impact resistance cannot be obtained.

The ratio of the ethylene-vinyl acetate copolymer resin to be added is determined as appropriate depending on the intended use of the resulting adhesive composition and the type of resin to be added, but it is 1 to 1 to α-cyanoacrylate.
An addition of 15% by weight is preferred.

If it is less than 1% by weight, there is no effect of imparting impact resistance, and if it is more than 15% by weight, the instant adhesive property, which is a characteristic of α-cyanoacrylate, will be impaired.

When adding and mixing these ethylene-vinyl acetate copolymer resins, they may be directly mixed with α-cyanoacrylate, or may be added and mixed after being dissolved in a suitable solvent.

It is also possible to add and mix fillers, softeners, stabilizers, etc. as necessary, such as fillers such as carbon black, red iron, calcium silicate, titanium oxide, DBP,
Softeners such as , DOP, TICP, tributoxyethyl phosphate, and various other esters; stabilizers such as sulfur dioxide gas, hydroquinone, and trimethyldihydroquinone; and other polymers that are compatible with α-cyanoacrylates such as methyl methacrylate. etc. can be added and used in combination.

The α-cyanoacrylate adhesive obtained by the combined use of the ethylene-vinyl acetate copolymer resin of the present invention has significantly improved impact resistance and is also significantly thickened, and as a result, α-cyanoacrylate alone It is now possible to bond porous materials that could not be bonded with other methods, and since the volumetric shrinkage rate during polymerization is also reduced, it is possible to prevent phenomena such as deformation or peeling of the bonded object.

Next, the present invention will be explained with examples.

Examples 1-4 500 ml in a four-eye flask with a capacity of 300 m1 equipped with a stirrer
Prepare 200g of ethyl-α-cyanoacrylate containing ppm of hydroquinone and 20ppm of sulfur dioxide gas,
While stirring, small pieces of ethylene-vinyl acetate copolymer resin shown in Table 1 were added.

Next, the mixture was heated and dissolved in an oil bath at 70° C. under a tightly closed stopper, mixed uniformly, and allowed to cool while stirring. The viscosity of the adhesive composition thus obtained, the fixing time, tensile shear strength, and impact strength when the adhesive composition was used to join steel to steel were measured. The results are shown in Table 1.

The above adhesion time is based on a polished and degreased steel butt piece with an adhesion area of 1 ent, at a temperature of 20°C and a humidity of 50±5.
After applying the adhesive under the conditions of %R2, the two pieces were placed on top of each other and left to stand, and the time required to obtain a tensile strength of 8 kg/cnff was measured.The tensile shear strength was determined by polishing and degreasing. Using mild steel plates measuring 25 x 100 x 1.6 mm, they were overlapped with an adhesive area of 12.5 x 25 mm, cured for 24 hours, and then tested using a tensile tester (Shimadzu Corporation).
S-5000) at a tensile speed of 50 mm/min.

Impact strength was determined by gluing steel test pieces (25 x 25 x 6 mm) according to the ASTM-D950-54 standard, and after curing for 24 hours using an Izotsu impact strength tester (newly manufactured by Toyo Seiki).
The impact strength was measured using Environmental conditions are 20℃, 6
It is 0%RH.

Example 5 In the same manner as in Examples 1 to 4, 10 g of dichloromethane and 1
After charging 80 g of ethyl-α-cyanoacrylate, Solex DH (Nippon Gosei Kagaku Kogyo Co., Ltd.) was added while stirring.
Made of ethylene-vinyl acetate copolymer resin, vinyl acetate content 70%
) was dissolved and mixed to obtain a composition. Table 1 shows the physical property test results.

Comparative Examples 1-2 Granular Gosenil PV-500 (
A composition was obtained by dissolving and mixing vinyl acetate resin (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.). Table 1 shows the physical property test results.

In addition, the viscosity and adhesion test results of ethyl-α-cyanoacrylate without the addition of other resins are shown in Table 1 as Comparative Example 2.

From the results in Table 1, it is clear that the adhesive strength of the present invention, especially the impact resistance, is significantly improved compared to the conventional cyanoacrylate adhesive without any loss in instant adhesive properties.

Patent applicant: Taoka Chemical Industry Co., Ltd.

Claims (1)

[Claims] An adhesive composition characterized in that an ethylene-vinyl acetate copolymer resin is added to α-cyanoacrylate.